CCP Composites Cookbook

CompositesApplications Guide

A WORD TO OUR VALUED CUSTOMERS . . .

As your partner in the composites products industry, CCP remains committed to your success by providing the latest incomposites technology.

We believe that commitment goes well beyond the research, development, and manufacture of the best products on themarket. By publishing this eleventh edition of the CCP Composites Application Guide, our technical staff also provides thecritical how to’s—that is, expert advice and information to assist you with product selection, application techniques,processes, equipment, troubleshooting, and environmental regulations, as well as other crucial considerations.

Over these eleven editions of the Application Guide, the products we make—and the products you make—have seenmany changes.

With the implementation of new standards and regulations, we all are challenged with making the transition to newprocesses and materials. We want that experience to be smooth and trouble-free for you. From low HAP materials to no-HAP processes, this manual will provide detailed information on emerging markets and technologies.

Customer satisfaction and product quality are the highest priority at CCP. It is our goal to more than meet the expectationsof our customers. We hope this manual will serve you not only as a tool in support of the products you make, but as animportant element in our ongoing business relationship.

As always, we welcome your comments and suggestions.

ABOUT CCP’S WEBSITE . . .

CCP’s website, www.ccponline.com, is a resource where you will find a wealth of valuable information, any day, any time.Composites product data sheets and MSDSes are all available in printable PDF format. You will also find a handyinteractive map with contact information for product distributors in your area. Within the What’s New area, you can trackCCP’s participation in industry trade shows and keep up with other announcements pertinent to your business operations.

As always, we value your input regarding our website and appreciate your ideas on how we can make the site even moreuseful to you. E-mail your comments to [email protected].

Cook Composites & PolymersP.O. Box 419389 Kansas City, MO 64141-6389

Ph: (816) 391-6000 Fax: (816) 391-6125www.ccponline.com

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COOK COMPOSITES AND POLYMERS CO.

WARRANTIES, DISCLAIMERS, AND LIMITATION OF LIABILITY (Rev. 03/09)

Seller warrants that: (i) Buyer shall obtain good title to the product sold hereunder, (ii) at Shipment such product shall conform to Seller’s specifications; and (iii) the sale or use of such product will not infringe the claims of any U.S. patent covering the product itself, but Seller does not warrant against infringement which might arise by the use of said product in any combination with other products or arising in the operation of any process. SELLER MAKES NO OTHER WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION ANY WARRANTY OF MERCHANTABILITY OR FITNESS FOR ANY PARTICULAR PURPOSE, EVEN IF THAT PURPOSE IS KNOWN TO SELLER, ANY APPLICATION INFORMATION OR ASSISTANCE WHICH SELLER MAY FURNISH TO BUYER IS GRATUITOUS AND SHALL IN NO WAY BE DEEMED PART OF THE SALE OF PRODUCT HEREUNDER OR A WARRANTY OF THE RESULTS OBTAINED THROUGH THE USE OF SUCH PRODUCT.

Without limiting the generality of the foregoing, if any product fails to meet warranties mentioned above, seller shall at seller’s option either replace the nonconforming product at no cost to Buyer or refund the Buyer the purchase price thereof. The foregoing is Buyer’s sole and exclusive remedy for failure of Seller to deliver or supply product that meets the foregoing warranties. Seller’s liability with respect to this contract and the product purchased under it shall not exceed the purchase price of the portion of such product as to which such liability arises. Seller shall not be liable for any injury, loss or damage, resulting from the handling or use of the product shipped hereunder whether in the manufacturing process or otherwise. In no event shall Seller be liable for special, incidental or consequential damages, including without limitations loss of profits, capital or business opportunity, downtime costs, or claims of customers or employees of Buyer. Failure to give Seller notice of any claim within thirty (30) days of Shipment of the product concerned shall constitute a waiver of such claim by Buyer, Any product credit received by Buyer hereunder, if not used, shall automatically expire one (1) year from the date the credit was granted. Notwithstanding any applicable statute of limitations to the contrary, any action by Buyer in relation to a claim hereunder must be instituted no later than two (2) years after the occurrence of the event upon which the claim is based. All the foregoing limitations shall apply irrespective of whether Buyer’s claim is based upon breach of contract, breach of warranty, negligence, strict liability, or any other legal theory.



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Composites Applications Guide

TABLE OF CONTENTS Copyright 2008

Part One—Introduction

A Word About Our Company ........................ 1 About CCP’s Website .................................... 1 Table of Contents .......................................... 2 CCP Trademarks ........................................... 3

Part Two—Health, Safety, and the Environment 4

Part Three—FRP Composites

I Introduction ................................................ 12 II General Chemistry of FRP Composites Resins 13 III General Properties of FRP Composites .... 17 IV Fabrication of FRP Composites ................ 21

Part Four—Open Molding

I Introduction ................................................ 24

II Conventional Gel Coat II.1 Materials .............................................. 25 II.2 Color .................................................... 27 II.3 Spray Equipment ................................ 32 II.4 Application ........................................... 49 II.5 Troubleshooting Guide ........................ 54

III Specialty Gel Coats III.1 Conductive Sanding ............................ 64 III.2 Metalflake ............................................ 65 III.3 Metallic ................................................ 69 III.4 Enamels .............................................. 71

IV Vinyl Ester Barrier Coats ........................... 73

V Lamination V.1 Laminating Resins .............................. 75 V.2 Fiber Reinforcements .......................... 78 V.3 Initiators ............................................... 81 V.4 Equipment/Application Methods ......... 82 V.5 Secondary Bonding ............................. 89

V.6 Acrylic Bonding ................................... 92 V.7 Troubleshooting .................................. 95

VI Painting Polyester Gel Coats .................... 98

VII Field Service VII.1 Cosmetics ........................................... 99 VII.2 Gel Coat Weathering ........................ 101 VII.3 Cracking ............................................ 111 VII.4 Swimming Pool Recommendations .. 113 VII.5 Blisters and Boil Tests ...................... 115 VII.6 Patching ............................................ 119

Part Five—Low Volume Closed Molding

I Introduction ............................................. 126 II Materials .................................................. 127 III Preform Constructions for Closed Molding 129 IV Process Features and Variations ............ 131 V Converting from Open Molding ............... 146

Part Six—Compression Molding

I Introduction ............................................. 157 II Materials/Typical Compound Formulations 158 III Compounding Processes and Equipment 161 IV Molding Processes and Equipment ........ 163 V Troubleshooting ...................................... 165

Part Seven—Casting

I Introduction ............................................. 168 II Cast Polymer ........................................... 169 III Solid Surface ........................................... 185 IV Flexible Casting Resins ........................... 187 V Thermal Shock Testing Request ............. 189



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TABLE OF CONTENTS Copyright 2008 Part Eight—Polyester Tooling

I Introduction .............................................. 192 II The Master Model .................................... 193 III Master Model Preparation ....................... 194 IV Applying Release Wax ............................ 195 V Building a Mold ........................................ 197 VI Mold Surface Distortion .......................... 205 VII Mold Break-In Procedures ...................... 207 VIII Mold Maintenance ................................... 209 IX Mold Resurfacing...................................... 210 X Mold Storage ............................................ 211

Part Eight—Polyester Tooling continued:

XI Special Precautions ................................. 212

Part Nine—ThermaCLEAN® Products ............ 214

Part Ten – IMEDGE® Products......................... 215

Part Eleven—Appendices

I Appendix A: Quality Control Lab/Test Methods .................................................................. 218 II Appendix B: Polyester Resin Bulk Storage ... .................................................................. 231

III Appendix C: Definitions of Terms .......... 234 IV Appendix D: Additional Information IV.1 Useful Conversion Factors .............. 246 IV.2 Drums (Stick Measurement) ............. 248 IV.3 Conversion Table/Materials Coverage ... .......................................................... 249 IV.4 Comparison of Sizes ....................... 250 IV.5 Temperature Conversion Table ....... 251 IV.6 Record of Current Products ............. 252 IV.7 Gel Coat Spray Test Sheet .............. 253 IV.8 Mixing .............................................. 254 IV.9 Catalyst Levels ................................ 255 IV.10 Application Helpful Hints .................. 256 IV.11 Wet-to-Cured ................................... 257 IV.12 Service Kit Items ............................... 258 IV.13 Equipment Maintenance/Cleanup ... 259 IV.14 Catalyst Precautions ........................ 260

Contact Information ........................................ 261

Inside Back Cover Partners in Composites Warranty, Disclaimer, and Limitation of Liability



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Page 3 of 3

Composites Applications Guide

CCP TRADEMARKS Copyright 2009

Listed below are trademarked CCP products designed specifically for the composites market. The CCP logo and trademarked product name assure optimum quality backed by a tradition of commitment to research.

ACPOL®—acrylic modified polymers.

AQUACLEAN™—machine-designed for cleaning tools used in composite parts manufacturing.

AQUAWASH®—water-based resin emulsifier cleaner.

ArmorCast®—casting resins designed for a wide variety of casting applications.

ArmorClear®—lower emission gel coat with improved flexibility and good weathering resistance.

ARMORCOTE®—in-mold coating with durability that far exceeds basic gel coat.

ArmorFlex®—gel coat with improved flexibility over standard gel coats.

ArmorGuard®—vinyl ester barrier coat designed for reducing osmotic blistering.

ArmorHP®—MACT compliant gel coat with superior weathering resistance and excellent processing characteristics.

ArmorPlus®—MACT compliant gel coat with improved flexibility and excellent processing characteristics.

ArmorPro®— MACT compliant gel coat with marine quality weathering, low tack and excellent processing characteristics.

ArmorStar®—epoxy-modified skin and bulk-laminating resins designed for the marine industry.

BathCote®—MACT compliant gel coat for the sanitary industry.

BathCote HFTM—MACT complaint gel coat for the sanitary industry with improved flexibility.

BUFFBACK®—gel coat with excellent gloss recovery in the repair process.

EASYCLEAN™—machine designed for cleaning tools used in composites parts manufacturing.

EPOVIATM—vinyl ester resins.

HiGlossTHPTM—MACT compliant, high performance gel coats for the transportation industry.

HiGloss TRTM—MACT compliant, high performance gel coats for the reinforced plastics industry.

IMEDGE®—Polymer Coating Technology (PCT) and Polymer Barrier Technology (PBT) high performance products.

LOVOCORTM— Low emissions in-mold coatings with the traditional quality of CCP gelcoats

MARBLECLEAN™—cleaning machine for cultured marble and solid surface.

MARBLEWASH®—nonhazardous solvent-based cleaner for use in MARBLECLEAN™ machine.

NUPOL®—thermosetting acrylic resin.

NuTACK®—aerosol tackifier for RTM, vacuum bagging, and infusion applications.

OPTIMOLD®—mold construction system that includes a filled tooling resin mix for rapid mold production.

OptiPLUS®—mold construction system for non-filled shrink controlled tooling resin.



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TABLE OF CONTENTS Copyright 2009 PATCHAID®—additive designed for gel coat and in-mold coating to improve patching results.

POLYCOR®—products of UPR, gel coats, and polymer systems.

QUICKMIXTM—Gel coat base and pigment pack system for easy inventory and on-site mixing

REPLACETONE™—water-based resin emulsifier.

STYPOL®—products of UPR, gel coats, and polymer systems.

THERMACLEAN®—nonhazardous cleaning products.

UNISOLVE™—universal solvent.

UNIWIPE™—low NVR surface cleaner.

Wipe-Bright®—surface cleaner.

XYCON®—family of hybrid polymers based on polyester (or other unsaturated polymers) and urethane chemistries; also considered an inter-penetrating polymers network.



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HEALTH, SAFETY, and the ENVIRONMENTPart TwoCopyright 2008


In This Section1. Introduction

2. Regulations

3. Safety

4. Fire Hazards

5. General Hazards of Materials Used

6. Health Hazards

7. Electrical Hazards

8. Equipment Hazards

9. HSE Information

1. INTRODUCTION—Health, safety, and theenvironment are of prime importance to allmanufacturers, especially those handling hazardousmaterials and chemicals. This has become a verycomplex issue with numerous federal, state and localregulations. Each user of a chemical product, such aspolyester resin and gel coat, must comply with federal,state and local laws that regulate production, employeeexposure, emissions, and shipping hazardous materialsand waste.

The following information is of a general nature only.Compliance requirements must be determined by theuser of the product. Information concerning the hazardsof these products can be found in the Material SafetyData Sheet (MSDS) and label for each product. Thesedocuments must be read. Polyester resins and gel coatscan be handled safely when proper precautions aretaken to protect workers, facilities, and the environment.

CCP products are intended for industrial users only.Sales to private individuals and home consumers is notrecommended nor endorsed. CCP does not sellproducts (nor recommend that they be sold) to privateindividuals for repairing their boats, tubs/showers, lawnfurniture, swimming pools, spas or saunas, farmimplements or equipment, automobiles, etc. There areplastic supply firms and automotive retail outlets thathave products available for fiberglass repair.

Information concerning health and safety regulations canbe obtained from OSHA, EPA, state and localgovernment offices or their websites. At the end of thischapter is a list of references, including websites wheremore detailed information can be obtained.

2. REGULATIONSA. Federal Regulations—The OSHA HazardCommunication Standard, 29 CFR 1910.1200,requires employers to evaluate chemicals used intheir workplaces to determine if they are hazardousand to transmit information on hazardous chemicalsto employees by means of a comprehensive trainingand in-plant hazard communication program.

OSHA establishes permissible exposure limits(PELs) for certain chemicals, such as styrene, whichhas an industry voluntary standard for permissibleexposure of 50 ppm, and an OSHA PEL of 100 ppm.

SARA TITLE III (EPA, 40 CFR 355) requiresemergency planning, chemicals inventory reporting,and toxic chemical release reporting.

The Resource Conservation Recovery Act (RCRA)includes ‘cradle-to-the-grave’ regulations, governingthe generation of storage, treatment, and disposal ofhazardous waste.

The Clean Air Act Amendments of 1990 (CAAA)regulate emissions of hazardous air pollutants (HAP)and volatile organic compounds (VOCs). Under theClean Air Act, two National Emissions Standards forHazardous Air Pollutants (NESHAP) have beenpromulgated that limit the HAP emissions from FRPprocesses. These NESHAPs govern ReinforcedPlastic Composite Production and BoatManufacturing. The NESHAPs establish HAPemissions standards based on the MaximumAchievable Control Technology (MACT).

The Department of Transportation regulatesshipment of hazardous materials and wastes.



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HEALTH, SAFETY, and the ENVIRONMENTCopyright 2008

B. State Regulations—State and/or localregulations must be at least as stringent as thefederal requirements.

California regulations place limits on VOC emissionsof resins and gel coats by limiting monomer contentand requiring specific application methods.

California also requires the label or data sheet tostate the amount of any VOCs in that product.

California Proposition #65 prohibits releases ofcertain chemicals into drinking water and requires‘clear and reasonable’ warning to persons potentiallyexposed to carcinogens and reproductive toxins.

Other states, such as New Jersey andPennsylvania, have regulations concerninghazardous materials.

Federal, state and local regulations are constantlychanging. Publications and trade organizations, such asthe ACMA or NMMA, are good sources for trackingregulatory information.

3. SAFETY—CCP encourages its customers todevelop a Safety Management System. Safety is theresponsibility of every employee. Fire losses and workerillnesses and injuries have occurred where good workpractices were not established or enforced.

The Safety Management System should designate theperson(s) responsible for the written safety programs(Hazard Communication, Personal ProtectiveEquipment, Lock-out/Tagout, Confined Space Entry,Exposure Control, Disaster Control, etc.) and employeetraining. Supervisors and employees should be aware ofhazards (see MSDS), necessary precautions, andincident reporting responsibilities.

Periodic safety inspections are recommended. MaterialSafety Data Sheets (MSDS) and other safety data for allhazardous materials found in the workplace must bekept on-site. All employees, supervisors, and workersshould be aware of proper handling and cleanupdirections when handling any hazardous material.

CCP strongly recommends that its customers establishan Emergency Action Plan or Emergency ResponsePlan for each facility.

4. FIRE HAZARDS—A fire is dangerous, destructive,and costly. It can start from a simple cause or acomplicated one. Knowing how fires start is the

foundation to knowing how to prevent one.

To sustain a fire, there must be:

• Fuel• Oxygen• Heat or an ignition source

If you remove any of these factors, a fire cannot occur.

A. Fuel—Quantities of a fuel source are requiredfor a fire. Resins or gel coats, in the liquid state, areflammable fuel sources. Resins or gel coats can alsobe combustible fuel sources when cured, or as adust. Most cleanup solvents, catalysts, and waxesare fuel sources. Composites plants have the usualfuel sources of paper, rags, wood, cardboard boxes,trash, etc. All fuel sources must be carefullycontrolled and minimized.

Resins and gel coats are found in four states in aplant:

• Liquid• Vapor• Solid• Dust

Vapors and dust are typically the most dangerous.Excess vapors and dusts must be avoided. Keepcontainers closed or covered when not in use.Controlled dust should be reduced and not allowedto accumulate.

Vapors are created from spraying, heating fromcuring parts, evaporation, etc. Vapors from resin andgel coat are heavier than air (sink to the floor) andmay collect in low spots. Vapors and dust cannormally be removed from a plant by effectivemechanical ventilation.

NOTE: Check for federal, state, and local codes onexhausting and/or discharging any materials directlyinto outside air. These regulations must be followed.

Flammable liquid resin and gel coat are alsodangerous. It is essential to keep uncatalyzed resinand gel coat in closed containers when not in use,and stored in a separate area away from the workarea until needed. Do not store in direct sunlight orwhere excess heat is present. Wipe up or remove allspills or overspray as soon as possible.



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FIRE HAZARDS continued:

Liquid catalysts (peroxides) must be handledaccording to the manufacturer’s recommendations.Organic peroxides can be explosive and are themost dangerous fuels in a plant because theyprovide oxygen and fuel to a fire. They should bekept in their original containers, out of direct sunlight,not exposed to heat, free from contamination, andclosed when not in use.

Catalysts are oxidizing materials which will react (attimes explosively) with reducing agents, such ascobalt accelerators, metals, and strong acid. Acatalyst should never be diluted with acetone. If adiluted catalyst is necessary, use catalysts obtainedfrom a catalyst manufacturer or those diluentsrecommended by the catalysts’ manufacturer.Catalyst must always be kept or used in containerswhich will not react with the catalyst. See thecatalyst manufacturer’s MSDS for specificrecommendations. Overspray and catalyst mist mustbe minimized. Overspray must be wiped up andremoved immediately according to themanufacturer’s recommendations.

Special care must be taken with catalyzed resin orgel coat (e.g., oversprays and gun flushings, asthese mixtures have the individual hazards of all thecombined materials of resins or gel coats, catalyst,solvent, etc.). In addition, the chemical reactionbetween the resin or gel coat and catalyst producesheat which can possibly cause ignition of solvents,unmixed or high concentrations of catalyst, andother flammable materials. The amount of heatgenerated will depend on the amount of catalyst, thedegree of mixing, the temperature, the mass, andthe reactivity.

Catalyzed resin or gel coat must not be allowed toaccumulate. Gelled masses and sanding dustshould be removed at once or temporarily immersedin water until they can be removed.

Plant solid waste must be handled carefully.Trimmings, overspray and trash have thin raggedsections which can be ignited. Trash should not beallowed to accumulate. The cured parts are harderto ignite, but will burn.

Likewise, any finely divided solid material maypresent a fire or explosion hazard when dispersed

and ignited in air if the following conditions are met:

• The dust is combustible.• A cloud is formed exceeding the minimum

explosive concentration.• A source of ignition is present. Dusts should

be minimized and not allowed toaccumulate.

Wax mold release agents are also fuel sources.Care and caution must be used with these materialsand the materials used in their application andremoval. See the manufacturer’s MSDS forinstructions for handling, use, and storage.

B. Oxygen—Oxygen is necessary for any fire.There are two main sources of oxygen: air andchemically combined oxygen in the material itself. Allvolatile materials must be within certain ratios withair or oxygen to burn or explode. With polyesters(resins or gel coats), good mechanical ventilationcan dilute the fuel below its explosive limit.

Peroxides are a special case. Peroxides containchemically combined oxygen which can be easilyliberated for combustion by heat, chemical reaction,decomposition, contamination, etc. Since peroxidesare also fuels, all that remains for a fire is heat or asource of ignition.

Because of this, peroxides require additional care tobe used safely. Storage should be separate fromother flammable or combustible materials. Closecontainers when not in use. Spills, gun flushings,and oversprays should be removed immediately.See the manufacturer’s MSDS forrecommendations.

C. Heat—Heat or a source of ignition is necessaryfor a fire. This can be a match, cigarette, flame, hotfilament, exotherming resin or gel coat, heater, pilotlight, spark (metal or hard surface or static), arcing ofan electric motor or wires, etc.

Dusts and vapors require a smaller ignition sourcethan liquids or cured parts to start a fire.

To avoid these hazards, ignition sources must beremoved from spray areas, working and storageareas.



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FIRE HAZARDS/ Heat continued:

One source of heat that must not be overlooked isfrom the chemical reaction of resin or gel coat and/orperoxides. Polyesters produce heat when they geland cure. The amount of heat produced depends onthe amount of catalyst and its degree of mixing, thetemperature, the mass, the resin to filler ratio, andthe reactivity.

Trimmings, overspray, flushed material from sprayguns, and dust from sanding and grinding should beremoved at once or temporarily dispersed in wateruntil they can be removed.

A good safety program works to remove, control, orminimize all three elements.

The following results indicate that closed cup flashpoints are lower than open cup flash points. Thisdata also shows that the addition of acetone to a gelcoat significantly lowers the flash point.

FLASH POINT DATA

Material Closed Cup & Flash Point

(Approx.)Acetone ........................... 0°F

Methyl Ethyl Ketone ........ 20°F

Ethyl Acetate ................... 24°F

Styrene ........................... 88°F

Polyester Gel Coats ........ 79 to 88°F

Methyl Methacrylate ........ 51°F

CCP does not recommend the addition of acetone orany other solvent to resins or gel coats.

The following extinguishing agents may be used onresin or gel coat fires:

• Foam• Dry chemical• Water fog• Carbon dioxide

If electrical equipment is involved, the use of foam orwater should be avoided.

NOTE: Direct streams of water may spread a fireinvolving solvents or monomers due toincompatibilities and density differences. Theburning material often floats on water.

By properly handling catalysts and accelerators,controlling vapors, and keeping the shop safelyclean, much can be done to reduce the risk of fire.With these factors controlled, a compositesoperation is relatively safe.

5. GENERAL HAZARDS OF MATERIALS USED—

A. Catalysts (Initiators)—Read the MSDS for allcatalyst products. The catalysts required for curingresins and gel coats are usually organic peroxides,such as methyl ethyl ketone peroxide (MEKP) andbenzoyl peroxide. By their nature, organic peroxidesare usually highly flammable and may decomposeexplosively.

Initiators are tested for heat sensitivity, shocksensitivity, burning rate, flash point, storage stability,and reaction to blasting caps to determine theirrelative hazards.

Obtain the manufacturer’s MSDS and productinformation to learn more about how to safelydispose of unwanted or old initiators.

According to NFPA 43B, incompatible materials(such as accelerators) and flammable liquids shouldnot be stored within 25 feet of organic peroxides.The effective separation distance should bemaintained by floor slope, drains, dikes, two-hourfire wall, or detached storage building to preventflammable liquid leaks from entering the organicperoxide storage area.

Only closed containers should be permitted in thestorage areas. No more than a one-day inventoryquantity of initiator should be brought from storageinto the work area.

Initiators should never be added or allowed tocontact accelerator which has not been added andwell-mixed with large, diluting quantities of resin orgel coat. The best procedure is to first mixaccelerator in the resin until a homogenous mix isobtained, then add the initiator. See manufacturer’shandling precautions.

A very small amount of peroxide initiator can makedrastic changes in the physical properties of a resinor gel coat. CCP emphasizes the importance offollowing the proper procedures in handling thecommercial forms of these products. Failure to do socan lead not only to poor performance of the initiator



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GENERAL HAZARDS OF MATERIALS USED/Catalysts continued:

but also, in some instances, to a violentpolymerization or decomposition.

Storage conditions and contamination are potentialsources of risk in handling peroxide initiators:

1) Heat—Do not expose organic peroxides toany form of heat, such as direct sunlight, steampipes, radiators, open flames, or sparks. Heat maycause organic peroxides to decompose violently,and they will burn if ignited. Never exceed theperoxide manufacturer’s recommended storagetemperature or conditions.

2) Metals—Do not let organic peroxides comein contact with easily oxidized metals such ascopper, brass, and mild or galvanized steel. Ifreplacement parts must be installed on peroxidehandling equipment, use the same materials ofconstruction as specified by the manufacturer of theequipment.

Metal contamination, such as dust fromgrinding, can produce serious consequences. Forexample, installation of a brass relief valve on acatalyst pressure pot or a brass connector in acatalyst line could cause the peroxide that comes incontact with the brass to decompose. Under suchconfined conditions, the decomposing peroxidecould develop enough pressure to burst thepressure pot or the initiator line.

3) Promoters and Accelerators—Never mixorganic peroxides directly with promoters oraccelerators. Such mixtures can be explosive. Inaddition, never contaminate initiators with resin orresin over-spray because the resin may containenough promoter to decompose the peroxide. Asmall amount of promoter goes a long way.Promoters are not consumed; they just continue todecompose the peroxide. The peroxidedecomposition produces heat. This heat speeds upthe action of the promoter, which then producesmore heat; and so the cycle can continue until thepoint is reached where the remaining peroxidedecomposes violently.

4) Solvents or Diluents—If a solvent is used toclean organic peroxide handling equipment, be sureto dry off the solvent before using. Some solvents,such as acetone, can react with peroxides to form

unstable peroxides of their own. Small amounts ofthese unstable ‘solvent peroxides’ can cause theexplosive decomposition of commercial peroxides.

If it is necessary to dilute an organicperoxide, be sure to consult with the peroxidemanufacturer for compatible solvents. Never usecontaminated solvents. Never use reclaimedsolvents unless they have been tested by theperoxide manufacturer. For greatest safety, obtainthe manufacturer’s diluted organic peroxides.

5) Always store an organic peroxide in itsoriginal container. If it is necessary to transfer ormeasure out some peroxide, use cleanpolyethylene, polypropylene, Teflon

®, or stainless

steel containers, funnels, etc.6) Other—Other types of contaminants to be

avoided when working with organic peroxides aredirt, resin or gel coat sanding dust, acids, bases, andstyrene. Further information on the proper handlingof peroxides is available on request from catalystmanufacturers.Basic guidelines regarding organic peroxidesinclude:

1) Read the MSDS (Material Safety DataSheet).

2) NO SMOKING around peroxides (or anypolyester or associated materials).

3) Organic peroxides and promoter (forexample, MEKP and cobalt) should NEVER bemixed directly with each other—a violent reaction willoccur!

4) Organic peroxides should always be storedseparately from promoters. Consult local insuranceinspection bureau and fire authorities for guidance.

5) Organic peroxides should not be allowed to‘sit around.’ Take only as much as will be usedduring each shift. If the peroxide is transferred intoanother container, use a container made of asuitable material such as polyethylene.

6) Always wear eye protection. Rubber glovesand face shields are also recommended.

7) Organic peroxides should not be stored in arefrigerator that also contains food or water, norshould they be poured into or stored in containersthat could be mistaken for other items, such as asoda pop bottle, baby bottle, etc.



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GENERAL HAZARDS OF MATERIALS USED/Catalysts/Other continued:

8) Dilution of organic peroxides by the end useris not recommended.

9) Although the flash point of some organicperoxides is higher than other chemicals usuallyfound in the typical composites operation, it ismisleading to think that peroxides are ‘safer’ withregard to fire. While it will take a hotter temperatureto get them to burn, they will decompose and auto-ignite sooner than the other chemicals. Thedecomposition temperature is 145°F to 170°F.

10) Do not expose organic peroxides to anyform of heat such as direct sunlight, steam pipes,radiators, open flames, or sparks.

11) Do not let organic peroxides come in contactwith easily oxidized metals such as copper, brass,and mild or galvanized steel.

12) Most organic peroxide suppliers have safetyprograms available (including videos or CD’s).Contact the supplier to request a ProductStewardship visit.

13) Always store organic peroxides at or belowthe recommended temperature as specified by themanufacturer.

14) ‘Red’ organic peroxides are believed bysome to be less stable than clear. Rotate inventoryof red organic peroxides frequently.

15) These safety considerations are not allinclusive. The organic peroxides supplier should becontacted for specific safety recommendations.

B. Accelerators—Read the MSDS. Some of theaccelerators commonly used are extremelyhazardous. Diethylanaline (DEA) anddimethylanaline (DMA) are particularly hazardoussince even small splashes may be absorbed throughthe skin, resulting in contact dermatitis. Headache,nausea, breathing irregularities, or fainting mayoccur soon after breathing vapors of these materials.If excessive quantities are inhaled, even moresevere reactions, including poisoning or death, mayoccur.

C. Styrene and Solvents—Read the MSDS. Somemonomers and cleanup solvents used may havehealth effects. Physiological health problems mayoccur from overexposure. For specific informationregarding the health hazards of specific products,

consult the manufacturer’s Material Safety DataSheet.

The accumulation of styrene and solvent vaporsprovides one of the conditions for an explosion orflash fire. A static charge or simple spark ignitionsource is all that is needed. Vapors should beimmediately removed by a good ventilation system.

California Air Quality Management District rulesrequire that the maximum loss of volatile organiccompounds (VOCs) of all VOC-containing productspackaged in quarts or larger be reported. Thisincludes CCP’s gel coat and resin product lines.

As a result, a series of tests were performedaccording to the Standard Method for Static VolatileEmissions on catalyzed polyester resins and gelcoats. The maximum quantity of VOCs notconsumed during polymerization was found to be 40grams per liter (or 230 grams per meter consideringsurface area exposed to air) for all catalyzed CCPresins and gel coats measured in a gallon can lid.For all uncatalyzed CCP resins and gel coats, themaximum VOC content is 600 grams/liter.

Copies of this VOC content information should beretained and available for compliance inspections.

Depending on the application equipment, thetemperature, and gel time, gel coats may lose 20 to25 percent of the pounds sprayed, or up to 65percent of the monomer(s) present.

Styrene, a typical monomer, can be lost from gelcoats in two ways. When gel coat is atomized,styrene evaporates as the gel coat travels from theend of the gun to the mold. The loss of styrene atthis point is controlled by temperature, method ofatomization, spray distance, and the degree ofbreakup (atomization).

The second loss occurs as the gel coat cures on themold. During this time period, the loss is governedby the evaporation rate of styrene. Once the surfacefilm is gelled, the evaporation rate drops offdramatically. This loss of styrene is influenced by thegel time, temperature, film thickness, surface area,mold configuration, and air movement.

Styrene monomer is flammable and forms explosivemixtures with air:



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GENERAL HAZARDS OF MATERIALS USED/Catalysts/ Styrene and Solvents continued:

• The lower explosive limit is 1.1 percent.• The upper limit is 6.1 percent (percent by

volume).

When styrene vapor is present in concentrationsbetween these limits, any source of ignition cancause an explosion.

Styrene Ignition Temperatures

Flash point is the lowest

temp-erature at which a

substance gives off

enough vapors to form a

flammable or ignitable

mixture with air near the

surface of the substance

being tested.

Flash point of styrene

is 31°C (87.8°F)

Fire point is the lowest

temp-erature at which a

liquid in an open

container will give off

enough vapors to

continue to burn when

ignited. Fire points are

generally slightly above

flash points.

Fire point of styrene is

34°C (93.2°F).

Auto-ignition temperature

is the lowest temperature

required to initiate or

cause self-sustained

combustion in the

absence of a spark or a

flame.

Auto-ignition temp-

erature of styrene is

490°C (914°F).

Adequate ventilation (especially the use of fumehoods) is recommended. Open flames, local hotspots, friction, and static electricity must be avoided.

D. Disposal of Cured Unsaturated Polyester—Discarded solid plastic materials from amanufacturing process utilizing unsaturated resinsor gel coats cured with organic peroxides, likemethyl ethyl ketone peroxide, constitute an industrial

solid waste. As required by 40 CFR 262.11 (andcorresponding applicable state regulations), thegenerator of this waste is required to determine if itis a hazardous waste.

This process would involve the determination if thesolid waste is classified as a listed hazardous waste,either as a discarded commercial product (40 CFR261.33), as a specific source waste (40 CFR261.32), or as a nonspecific source waste (40 CFR261.31). The generator must then determinewhether the waste meets the characteristics ofhazardous waste defined in 40 CFR 261, Subpart C.These defined characteristics are:

Defined Characteristics of Hazardous Waste

Ignitability Corrosivity Reactivity Toxicity

Since the waste is not a liquid with a flash point ofless than 140°F, a nonliquid which may ignitespontaneously or by friction, an ignitablecompressed gas, or an oxidizer, it does not exhibitthe characteristics of ‘Ignitability.’ Likewise, thewaste does not exhibit the characteristics of‘Corrosivity’ (aqueous pH less than two or greaterthan 12.5 or corrodes steel), or of ‘Reactivity’ (i.e.,normally unstable, violently water reactive, orcapable of generating toxic gases, vapors or fumesin contact with water). Depending on the level ofmethyl ethyl ketone peroxide used, the solid wastemay be classified as hazardous because of toxicity.Methyl ethyl ketone is listed in Table 1 of 20 CFR261.24.

All generators of solid wastes of this nature shouldretain a written determination in their records withdocumented data or generator knowledge on wasteprofiles for all wastes which they generate. This isrequired by federal and state regulations.

6. HEALTH HAZARDS—Read the MSDS for healthhazard warning information for all materials used in theworkplace. Most materials used in a manufacturingfacility may be hazardous if not properly or carefullyhandled. Each chemical should be consideredseparately, and looked at in reference to other chemicalswith which it can come in contact or react with to



Page 7 of 12


HEALTH HAZARDS continued:

produce new chemicals. Chemicals may enter the bodythrough several routes of entry, including inhalation,ingestion, absorption, or injection. Consult the MSDS(Material Safety Data Sheet) to determine acceptableexposure levels and emergency response procedures.

Both the OSHA Hazard Communication Standard andcertain state regulations require that manufacturersplace precaution labels on containers of manufacturedproducts, and provide to each customer Material SafetyData Sheets that list the acute (immediate) and chronic(delayed) hazards of their products.

Contact with hazardous materials must be minimized.Resins, gel coats, solvents, initiators, etc., should notcome in contact with the body. Where contact isunavoidable, protective equipment (clothing, gloves,etc.) should be used and all spills cleaned up at once.

Safety glasses or goggles must be worn at all times in allworking areas.

If the possibility of vapor or dust is present, adequateventilation is necessary. NIOSH-approved ‘hood-type’supplied air respirators are recommended forapplications with high vapor or dust levels. NOTE: Airsupplied to the hood must be absolutely clean andseparate—no exhaust vapors or compressor oil. Alldusts should be removed by adequate ventilation andwith an adequate face mask being worn. Do not use airto blow dust off a person. Remove by washing with coolwater.

Pigments used by some gel coat suppliers may containlead and hexavalent chromium compounds. OSHAregulations require workplaces with lead-containingmaterials to monitor worker exposure. Because of thenumber of recognized health hazards associated withthe use of lead and heavy metal pigments, CCP doesnot use lead or heavy metal pigments in its resin or gelcoat products.

Two types of lead/chromium pigments used by some gelcoat suppliers are described as:

CHROME YELLOW

• Classified as Light and Primrose• Contains Lead Chromate• Lead is a reproductive toxin and affects various

body systems and organs adversely.

• Hexavalent Chromate is considered arespiratory carcinogen.

MOLY ORANGE

• Bright Orange and Scarlet shades• Is a compound of Lead Chromate, Lead

Molybdate and Lead Sulfate• Has the same lead and chromate hazards asChrome Yellow.

Many states have regulations to control the use andwaste disposal of mixtures containing lead andhexavalent chromate. The OSHA OccupationalExposure to Lead Standard, 29 CFR 1910.1025, definesrequirements of workplaces with employees who may beexposed to lead. Compliance procedures required bythis standard include:

A. Make an initial determination of employeeexposure by monitoring the work space in whichlead may be present.

B. Employee exposure is that exposure whichwould occur if the employee were not using arespirator.

C. Notify employees within five days of the receiptof monitoring results that represent that employee’sexposure.

D. If monitoring results show employee exposure tobe at or above the action level of 30 micrograms oflead per cubic meter, additional monitoring isrequired.

E. If monitoring results show employees areexposed to lead above the permissible exposurelevel of 50 micrograms per cubic meter, periodicmonitoring, medical surveillance, engineeringcontrols, employee notification, and respirators maybe required.

If the decision is made to monitor for lead orchromium, qualified industrial hygiene consultantsfor monitoring and testing services may be obtainedby contacting:

American Industrial Hygiene Association2700 Prosperity Ave., Suite #250Fairfax, VA 22031Ph: 703-849-8888Fax: 703-207-3561www.aiha.org



Page 8 of 12


7. ELECTRICAL HAZARDS—The two main hazardsfrom electrical equipment are sparks and shock. Allequipment, power lines, lights and connectors should beexplosion-proof and effectively grounded.

All possible sources of static discharge should beeliminated through adequate grounding or othermeasures. This includes spray guns, holding tanks,transfer lines, etc.

8. EQUIPMENT HAZARDS—A composites operationmay use many power tools. All tools which haveexposed turning parts should have guards to preventhands and clothing from being caught in them. Allpersons should be properly trained in the use of powertools. Spray guns should be grounded, worn fittings andhoses replaced.

NOTE: Airless spray equipment develops enoughpressure to force material through the skin. Safeguardsmust be taken to prevent this. Any person who sprays,regardless of equipment type, must be adequatelytrained and be made aware of how to protect himselfand others from these hazards.

Before starting repairs on spray equipment or anyequipment with moving parts or internal pressure, turnoff and disconnect all power sources and bleed off ALLinternal pressures. Care must be taken with chopperguns because cutting blades and glass roving cutanything with which they come in contact.

Well-run housekeeping and order programs that includetrash removal, spill cleanup, and regular equipment andbuilding maintenance will reduce fire and health hazardsin the workplace. Such programs save money, promoteefficiency, and increase job satisfaction.

9. HEALTH, SAFETY, AND ENVIRONMENTALINFORMATION—The references listed below are givenas a guide only. This is not meant as a recommendationor endorsement of any of these references or services.They are listed as a sample of the type of informationthat is available.

There are many sources of information and guidance onhealth, safety, and environmental matters, for example:

• Company insurance carrier• Local Fire Marshal• Suppliers (product stewardship)

Other sources of information are:

REGULATIONS/COMPLIANCE

United States Environmental Protection Agency(EPA)www.epa.gov

United States Department of Transportation (DOT)www.dot.gov

Occupational Safety and Health Administration(OSHA)www.osha.gov

American Composites Manufacturing Association1010 Glebe Road, Ste 450Arlington, VA 22201Ph: 703-525-0511Fax: 703-525-0743www.acma.org

National Marine Manufacturer’s Association (NMMA)200 E. Randolph Drive, Ste 5100Chicago, IL 60601Ph: 312-946-6200www.nmma.org

FIRE SAFETY

National Fire Protection Association (NFPA)www.nfpa.org

No. 13 — Sprinkler Systems

No. 30 —Flammable and CombustibleLiquids Code

No. 68 — Explosion Venting Guide

No. 69 — Explosion Prevention System

No. 70 — Electric Code

No. 77 — Static Electricity

No. 91 — Blower and Exhaust System

No. 654 —Prevention of Dust Explosionsin the Plastics Industry



Page 9 of 12


CHEMICAL HEALTH HAZARDS

National Toxicology Program (NTP)National Institutes of Healthwww.nih.gov

Styrene Information Research Center (SIRC)www.styrene.org

International Agency for Research on Cancer (IARC)World Health Organizationwww.iarc.fr

COMPLIANCE GUIDES

J. J. Keller and Associates, Inc.Ph: 800-327-6868

LabelmasterPh: 800-621-5808

Thompson Publishing Co.Ph: 800-677-3789

Business & Legal Reports, Inc.Ph: 800-727-5257www.blr.com

Summit Training Source, Inc.Ph: 800-842-0466



Page 10 of 12




Page 11 of 12







Page 12 of 12

FRP COMPOSITES: Introduction


Part Three, Chapter ICopyright 2008

In Part Three:Chapter I: Introduction

Chapter II: General Chemistry of FRP Composites

Resins

Chapter III: General Properties of FRP Composites

Chapter IV: Fabrication of FRP Composites

A composite material is an engineered product made bycombining dissimilar materials that remain separate anddistinct from each other on a macroscopic level. Theresulting material has a unique set of characteristics andqualities that is more useful than any of its individualconstituent materials.

Any composite consists of a matrix material and areinforcing material. The matrix surrounds thereinforcement, maintaining the relative positions of thereinforcements. The matrix serves to transfer loads fromthe surface of the part into the reinforcement materialand between reinforcements. Almost any material canfulfill the matrix role. A few examples of broad categoriesof matrix are:

• Mud • Cement• Pitch • Rubber• Plastic • Ceramic• Carbon • Metal• Glass

The reinforcement can take numerous forms such as:

• Powdered or aggregate minerals• Whiskers (very short fibers)• Chopped fibers• Continuous fibers

Fibers can be fashioned into textile products such asfelts or cloths, or fabrics of various constructions. Fibermaterials can be composed of a wide variety of materialssuch as glass, carbon, silicone carbide, boron, mixedceramics, a number of different polymers, and naturallyoccurring materials such as hemp.

Composite materials are different from conventionalmaterials in many ways. Most significantly, they achievetheir properties and characteristics only after beingsuccessfully processed in the manufacturing facility.They are composed of truly ‘raw’ materials. Age ofmaterials, their storage, and processing temperaturesare only three of the variables that must be managedand controlled.

In contrast, a so-called raw material, such as aluminumsheet, arrives on a skid with all of its properties andcharacteristics intact, and it keeps them indefinitely,barring some very extreme exposure conditions. Thehandling and usage of composite materials is not unlikethe handling and usage of food items. Quality requiresfreshness, while consistency requires adherence to ‘therecipes’ and attention to process details. It is no surprisethat this application guide has become knownthroughout the world as the Cook Book.

Composite materials consisting of Glass FiberReinforced Polyester (GFRP) resin are in widespreaduse throughout the world. These are generallyconsidered commodity-type composite materials.Applications range from fiberglass bathware to solid-surface countertops to decorative statues to vehicularbody parts to windmill blades and more. Almost anythingcan be molded using GFRP.

Glass fibers are composed of a mixture of inorganicmetal oxides. The principle constituent is silicone dioxidewith smaller amounts of aluminum oxide, calcium oxide,magnesium oxide, boron oxide, and zirconium oxide.Exact composition determines the end-use performance.There are at least seven commercially available glasstypes with the most common being E glass, followed byA glass and then C and S glass. Quartz fiber isessentially pure silicone dioxide and features one of thelowest dielectric constants of commercial materials.



Page 1 of 4

FRP COMPOSITES: IntroductionCopyright 2008

The class of resin chemistry determines the end-usesuitability for any application. Unsaturated polyesterresins provide a good balance of properties for a modestcost. Vinyl ester resins offer improvements in certainproperties such as strength and heat resistance, but aretypically higher in cost.

Fiber Reinforced Plastic (FRP) parts are molded to thedesign shape by using a cure tool and a moldingprotocol. Most cure tools are called molds, although notall molds are curing tools. The most common exceptionis a fiber preforming mold. A cure tool can consist ofseveral elements. At its very minimum, a cure toolconsists of a mold skin which mirrors the cured partabout its external surface. Larger molds incorporatebracing to reinforce local areas and framing to distributethe mold weight onto concentrated load points such ascasters, which also provide for mobility.

This guide pertains to one specific type of composite

known as Fiber Reinforced Plastic (FRP). The major

subcategory of FRP is Glass Fiber Reinforced Plastic

(GFRP or GRP). All three terms are sometimes used

interchangeably.



Page 2 of 4

FRP COMPOSITES: IntroductionCopyright 2008



Page 3 of 4







Page 4 of 4

FRP COMPOSITES: General Chemistry of FRP Composites Resins


Part Three, Chapter IICopyright 2008

In This Chapter1. Introduction

2. Synthesis of Polyester and Vinyl Ester Polymers

3. Types of Polyester and Vinyl Ester Resins

4. Curing Mechanism

5. Peroxide Initiators

6. Accelerators

7. Suggested References

1. INTRODUCTION—Thermoset polyester andthermoset vinyl ester polymers are the key ingredientsfor most CCP resins and gel coats, and are the basis forRTM, marble, casting, laminating, pultrusion, andmolding resins.

These versatile resins are used in a broad spectrum ofapplications, including:

• Building and construction• Corrugated and flat paneling• Reinforcements for acrylic sheet• Shower stalls, tubs and marble vanities• Interior and exterior auto body panels• Polymer concrete and mine bolts• Electrical components• Boat and other marine laminates• Corrosion-resistant tanks and components

Polyester and vinyl ester resins can be formulated fromrigid to flexible (or anywhere in between) and can becorrosion and water resistant. The resins are usedunfilled, filled, reinforced, or pigmented. Fabricators cancure polyester resins at temperatures that range fromambient up to 400ºF (204ºC).

When armed with the knowledge of how polyester andvinyl ester resins are made, and how they cure, thefabricator will more readily understand some of theimportant factors that affect them. This will support gooduse techniques with fewer problems. Knowledge andexperience provide the foundation for efficient production

methods and high-quality parts.

This chapter of the Applications Guide offers a briefdescription of the chemistry of thermoset polyester andthermoset vinyl ester resins. It is a guide to how theseresins are made and how they cure. Further informationis available in the references listed at the end of thischapter.

2. SYNTHESIS OF POLYESTER AND VINYL ESTERPOLYMERS—The building blocks for the synthesis ofpolyester and vinyl ester polymers come from thepetrochemical industry with their ultimate source beingoil and/or natural gas. Polyesters are comprised of threemain types of compounds: dicarboxylic acids (meaningtwo acid groups per compound), glycols (meaning twoalcohol groups per compound), and monomers/diluents.For vinyl esters, the building blocks are primarilydiepoxides, monocarboxylic acids, andmonomers/diluents.

To make polyester, the dicarboxylic acids and glycolsreact together under heat to form a long chaincompound called a polymer. Because the acids andglycols react together to form an ester in what is calledan esterification reaction, the resulting polymer is calledpolyester (literally ‘many esters’). Some of thedicarboxylic acids are unsaturated (having carbon-carbon double bonds) and for this reason the polyesteris said to be an unsaturated polyester. To form thepolymer, the acids and glycols are ‘cooked’ together in akettle. Cooking times can vary from 14 to 24 hours attemperatures up to 430ºF (221ºC). The progress of thecooking process, or ‘cook,’ is followed by measuring thereduction in acidity and the increase in viscosity. Wateris a by-product of the esterification reaction and boils outof the reaction kettle as it is formed.

Vinyl esters are also unsaturated esters that are formedvia an addition reaction between diepoxides andunsaturated monocarboxylic acids. Since theunsaturated function in vinyl esters typically comes frommethacrylic acid or acrylic acid, rather than maleic acid



Page 1 of 8

FRP COMPOSITES: General Chemistry of FRP Composites ResinsCopyright 2008

SYNTHESIS OF POLYESTER AND VINYL ESTERPOLYMERS continued:as is the case with unsaturated polyesters, thesepolymers only have unsaturated groups at the ends ofeach polymer chain. The ‘cooks’ for vinyl esters aretypically eight to 14 hours at temperatures up to about240ºF (116ºC). The processing parameters for vinylesters are very similar to those of unsaturatedpolyesters; however, no water is eliminated as this is anaddition rather than a condensation reaction.

Both polyesters and vinyl ester polymers in their pureforms are generally hard solids; similar to chunks ofglass. To make these polymers readily usable by thefabricator, they are dissolved in a monomer, usuallystyrene, which also has an unsaturated group neededfor the curing process we will discuss later. When thefabricator adds a peroxide initiator, the unsaturatedportion of the monomer reacts with the unsaturatedportion of the polymer to form cross-links. The resultingmaterial is a hard solid that will not soften, or melt, evenwhen heated to very high temperatures. For this reason,the resin is said to be a thermoset resin (thermoplasticresins can be remelted, and/or resoftened and thenshaped into other articles).

3. TYPES OF POLYESTER AND VINYL ESTERRESINS—The properties of a polyester resin dependson the types and amounts of the dicarboxylic acids,glycols used in cooking the polyester polymer, and themonomer the polyester is diluted in. The most commonunsaturated acid is maleic anhydride. Saturated acidssuch as phthalic anhydride, isophthalic acid, and adipicacid may also be included to impart different properties.Glycols include ethylene glycol, diethylene glycol,propylene glycol, dipropylene glycol, and neopentylglycol. Styrene is the most common monomer but othermonomers that can be used are vinyl toluene, alpha-methyl styrene, and methyl methacrylate. The structuresof some of these components are shown on thefollowing page.

Each of these components contributes to the finalproperties of the resin. Isophthalic acid and neopentylglycol increase moisture, chemical, and corrosionresistance. To improve resistance to weathering;neopentyl glycol, methyl methacrylate, and stabilizingadditives that protect against ultraviolet rays of the sunare used. Adding adipic acid and reducing the amount ofunsaturated acid results in a softer resin with increased

flexibility. In contrast, to increase rigidity, higher amountsof unsaturated acid are used, sometimes with higher-functionality monomers such as divinylbenzene. Thesematerials result in greater hardness and rigidity byincreasing the number, and density, of chemical bondsin the resin as it cures. To alter the flammabilitycharacteristics of a resin, acids such as chlorendicanhydride and tetrabromophthalic anhydride are used.

Another building block, generally used in laminatingresins, is dicyclopentadiene (DCPD). DCPD replacessome of the glycols and contributes to a faster tack-freetime, lower apparent shrinkage, and a smoother surfaceon cure. DCPD containing resins is primarily used instructural applications which require an excellentcosmetic appearance and reduced fiber print-through.

As with unsaturated polyesters, the properties of vinylester resins are very dependent on the choice of thepolymer’s building blocks. The most common vinyl esterresins employ the diglycidyl ether of bisphenol-A as thediepoxide and methacrylic acid as the unsaturatedmonoacid. The choices of monomers for vinyl esters arevery similar to that of unsaturated polyesters (meaningstyrene and methyl methacrylate). The structures of thebuilding blocks for vinyl esters are shown below:



Page 2 of 8


Modifications may include using a novalac epoxy (amulti-functional epoxy), maleic acid, specializeddiepoxides, and other mono-functional acids in additionto the basic ingredients mentioned above. Themodifications can impart increased strength, increasedflexibility, or modified cure behaviors depending on thechoices made. Vinyl esters are selected for applicationswhere mechanical strength and/or chemical or waterresistance demands are greater than can typically beobtained by conventional unsaturated polyester resins.

In addition to the unsaturated polyester and vinyl esterresins, CCP markets resin systems that are acombination of both polyester and polyurethane; theseare the CCP XYCON

®hybrids. The properties of the

hybrids reflect both the polyester and urethanechemistries. The XYCON

®hybrids exhibit excellent

toughness, crack resistance, fatigue resistance, lowershrinkage, adhesion, water resistance, and speed ofcure. They are used as a barrier coat in marineapplications to reduce fiber print-through and increasedblister resistance. In addition, the hybrids can beformulated for use in structural applications.

4. CURING MECHANISM—As previously noted, afterthe polyester or vinyl ester polymer is cooked, it isdissolved in monomer (usually styrene) so it is a readilypourable liquid that can be easily used by the fabricator.The ratio of polyester polymer to monomer ranges fromabout 75:25 to 50:50 parts by weight. Inhibitors areadded to the solution to prevent the monomer and theunsaturated acid in the polymer from reactingprematurely.

Both the gel and cure of a polyester or vinyl estersolution takes place by a free radical reaction. In thisprocedure, peroxide is added to the polymer solution bythe fabricator. The peroxide decomposes (splits apart)into two highly energized free radicals that react with theunsaturated portions of the polymer and monomer. Thepresence of the free radicals, together with theunsaturated functionalities of the polymer and monomer,results in the formation of new chemical bonds that‘cross-links’ the resin system.

Once cross-linking starts, movement of the polymer inthe solution is highly restricted. After only a small fractionof the unsaturated groups have reacted, the solution isgelled. Eventually, the polymer chains are cross-linkedby the monomer into one solid, infusible mass that willnot soften or melt on exposure to heat. Typically, in

laminating and casting applications, 80 to 90% of theunsaturated groups will have reacted by the time the partis demolded. The parts will reach 95 to 97% cure in twoto four months if kept above 70ºF (21ºC). Curing isaccompanied by the development of large amounts ofheat, commonly referred to as exotherm. The heat is theresult of the new chemical bonds being formed and thisheat also makes the curing reactions proceed evenfaster.

Inhibitors react very quickly with free radicals and areused to protect the polymer solutions against prematurecross-linking until the appropriate peroxide initiator isadded by the fabricator. Free radicals can form naturallyin the resin, and will form faster if the polymer solution isexposed to heat and/or sunlight, or is contaminated withmetals or other materials. For this reason, it is importantto store polyester resins in a cool, dark place asrecommended on CCP’s technical data sheets.

Factors that affect the curing reaction are:

• Temperature of the resin—The time to gel andcure the resin will be reduced in half with eachincrease in temperature of 18ºF (10ºC).Conversely, the time to gel and cure the resinwill double with each 18ºF (10ºC) decrease intemperature. If the temperature gets too low, thepolyester may never cure properly.

• Mass—The amount of resin, and its shape, willaffect the rate of cure. A thick casting will curefaster than a thin laminate because the castingwill generate more heat and will hold theexothermic heat better than the laminate. Verythin laminates may require a source of externalheat to cure properly.

• Peroxide initiator—The type and amount ofperoxide is based on the resin and the curingconditions. CCP data sheets specify types andamounts of peroxides. Peroxide initiators arediscussed in the following section.

• Accelerators—These additives increase therates of reaction between the free radicals andthe unsaturated groups. CCP adds accelerators(also called promoters) to its resins.Accelerators are discussed in a followingsection.



Page 3 of 8


5. PEROXIDE INITIATORS—The function of theperoxide is to initiate the cross-linking reactions in theresin. The cross-linking will first cause the solution to geland then cause the gel to completely cure. Whenperoxide is added to a resin, heat and/or theaccelerators in the resin decompose the peroxide intofree radicals. The free radicals first consume the inhibitorpresent in the resin and then react with the unsaturatedportions of the polyester polymer and the monomer. Thereaction product between an unsaturated compound anda free radical results in a second free radical which thenreacts with another unsaturated group. This forms a thirdradical, etc., etc., and cycle continues until the cross-links are formed. The whole process stops when the freeradicals are no longer mobile enough to contact otherunsaturated groups. This lack of mobility occurs whenthe viscosity of the curing system becomes very high.The remaining groups slowly cross-link as the part agesor when it is heated in a postcure step by the fabricator.

Some of the peroxides used to cure polyester and vinylester solutions are very unstable at room temperature

PEROXIDE INITIATORS continued:and must be stored under refrigeration. Becauseperoxides and accelerators react explosively, theyshould never be mixed directly together. For this reason,resins for use at room temperature generally comepreaccelerated (or prepromoted). If additionalaccelerator or promoter is needed, it should be mixedthoroughly into the resin before the peroxide is added.The precautions listed on the Material Safety Data Sheetfor each peroxide should be strictly observed.

Curing of polyester and vinyl ester resins can be dividedinto two groups: room temperature (65 to 95ºF (18 to35ºC)) and elevated temperature. Curing at elevatedtemperatures generally takes place in heated tools ormolds at temperatures from 180 to 320ºF (82 to 160ºC).Peroxides for use at these temperatures include t-butylperbenzoate, t-butyl peroctoate, benzoyl peroxide,peroxyketals, and other specialty peroxides.Accelerators are not generally needed to activate theseperoxides. Heat is enough to decompose theseperoxides into free radicals.

Room temperature cure is generally used in casting andlaminating applications. Methyl ethyl ketone peroxide(MEKP); cumene hydroperoxides (CHP); 2,4-pentanedione peroxide (2,4-P); or combinations of theseperoxides are generally used. To make these peroxides

usable, they are diluted with various plasticizers until anactive oxygen content of 4 to 9% is achieved.Accelerators added to the resins help to convert theseperoxides into the free radicals necessary for the gel andcure process.

MEKP is made from methyl ethyl ketone and hydrogenperoxide. These two reagents react to form severaldifferent peroxides. The MEKP supplied by mostmanufacturers is a mixture of peroxides and residualhydrogen peroxide. The exact composition of eachcommercial MEKP depends on the manufacturingprocess. Thus MEKPs from different manufacturersreact differently and should be checked before switchingfrom one to another. There are also small amounts ofwater and hydrogen peroxide in MEKP. These can alsochange the reactivity of the MEKP.

Some of the factors governing peroxide usage are:

• Amount—An adequate amount of peroxide mustbe used to start the process and bring it to finalcure. Resins and peroxide are formulated sothat from 0.75 to 3% solution is enough togenerate the free radicals needed. If too muchperoxide is used, too many polymer chains willstart growing. Too many chains started results inshort polymer chains, and the cured resin willhave poor physical properties. If too littleperoxide is used, the gel time will be very longand the growing polymer chains, may die outbefore all the unsaturated groups are reacted.The resin may never cure properly even ifpostcured. It will tend to be physically weak andpossibly rubbery.

• Heat—Enough heat must be supplied toproperly cure the resin. It can come from anexternal source such as an oven, heat lamps, ora heated mold. The heat can also come from theexotherm of the resin itself. If the exotherm isstronger, such as in a thick casting, the part willget hotter and cure faster. If the part is a thinlaminate then the exotherm will be weaker andthe heat will be easily dissipated because of thelarge surface area-to-volume ratio of the part.The result of this will be a slower cure.

• Shop conditions are very important. Iftemperatures are below 60ºF (15ºC), cure will begreatly extended. However, if the temperature is



Page 4 of 8


90ºF (32ºC) or above, then the gel and cure willbe faster. Cutting back on the peroxide mayresult in enough working time, but there may notbe enough free radicals to properly cure theresin.

6. ACCELERATORS—Resins formulated for cure atroom temperature contain accelerators (also calledpromoters). Accelerators increase the breakdown rate ofthe peroxide into free radicals. The amount of bothaccelerator and peroxide must be such that thefabricator has enough working time to form the part and,at the same time, enough speed of cure to make theprocess economically practical. CCP adds acceleratorsto its gel coats and resins (i.e., prepromotes them). Gelcoat and resin data sheets contain information on thetype and amount of peroxide initiator to use. CCP’sresins are tailored to meet fabricators’ needs; i.e., fastgel and cure, fast gel with slower cure for longer trimtime, longer gel with fast cure, etc.

ACCELERATORS continued:Accelerators used in CCP products are generally metalsalts (sometimes called metal soaps) and amines. Theyinclude cobalt, calcium and potassium salts, and aminessuch as dimethyl aniline and diethyl aniline.

Some of these accelerators are described as follows:

• Cobalt—Solutions of cobalt generally containfrom 6 to 12% metal. They impart a pink to red colorto the resin depending on the amount used. Cobaltacts on most peroxides to form free radicals. Cobaltalso affects perbenzoate and peroctoate initiatorsthat are used at intermediate temperatures 140 to180ºF (60 to 82ºC). Cobalt does not act as anaccelerator for benzoyl peroxide.

• Amines—Amines generally color polyesterresins yellow to brown depending on the amount ofamine used. They also can cause acceleratedyellowing of cured parts. Dimethyl aniline (DMA) anddiethyl aniline (DEA) do not act directly on MEKP oron 2,4-P (2,4-pentanedione peroxide). Theyincrease the ability of cobalt to convert theseperoxides into free radicals. They are very effectivein shortening the cure time and hardnessdevelopment of MEKP-initiated resins.

7. SUGGESTED REFERENCES

BOOKS

Plastics Engineering Handbook of the Society of thePlastics IndustrySociety of the Plastics Industry, Inc. (SPI)1667 K Street NW, Ste 1000Washington, DC 20006Ph: 202-974-5200Fax: 202-296-7005www.knovel.com/web/portal/basic_search/display?_EXT_KNOVEL_DISPLAY_bookid=347

Modern Plastics HandbookThe McGraw-Hill Companies, Inc.2 Penn PlazaNew York, New York 10121-2298Ph: 212-904-2000www.knovel.com/web/portal/basic_search/display?_EXT_KNOVEL_DISPLAY_bookid=1008

Reinforced Plastics HandbookElsevier Science Customer Service11830 Westline Industrial DriveSt. Louis, MO 63146 USAPh: 800-545-2522Fax: 800-535-9935www.elsevier.com/wps/find/bookdescription.cws_home/703711/description#description

PAPERS

Annual Conference ProceedingsAmerican Composites Manufacturing Association1010 North Glebe Road, Ste 450Arlington, VA 22201Ph: 703-525-0511Fax: 703-525-0743www.acmanet.org

Annual ProceedingsComposites Institute ConferenceSociety of the Plastics Industry, Inc. (SPI)*1667 K Street NW, Ste 1000Washington, DC 20006Ph: 202-974-5200Fax: 202-296-7005www.socplas.org

* Excellent resource but the conference no longer exists



Page 5 of 8


PERIODICALS

Composites Manufacturing1010 North Glebe Road, Ste 450Arlington, VA 22201Ph: 703-525-0511Fax: 703-525-0743www.cmmagazine.org

Composites Technology4891 Independence Street, Ste 270Wheat Ridge, CO 80033Ph: 303-467-1776www.compositesworld.com

Modern PlasticsCanon Communications LLC11444 W. Olympic Blvd., Ste 900Los Angeles, CA 90064Ph: 310-445-4200www.modplas.com

Professional BoatBuilderNaskeag RoadP.O. Box 78Brooklin, ME 04616Ph: 207-359-4651Fax: 207-359-8920www.proboat.com



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FRP COMPOSITES: General Properties of FRP Composites


Part Three, Chapter IIICopyright 2008


2. Mechanical Properties

3. Hardness

4. Specific Gravity

5. Thermal Performance

6. Chemical Properties

7. Electrical Properties

8. Fire Resistance

9. Optical Properties

10. Weathering Properties

11. Polyester Shrinkage

12. Technical Data Sheets

1. INTRODUCTION—Fiber Reinforced Plastic (FRP) orGlass Reinforced Plastic (GRP) is an adaptable material.FRP parts can be made with widely varying properties,depending on the type of resin matrix; the type, level andorientation of reinforcement; usage of fillers and otheradditives, as well as the fabrication process andprocessing conditions. As a result, FRP parts are used ina broad range of applications. These include:

Construction—Bathtubs, shower stalls andfloors, hot tubs, spas, vanities and sinks, pipes,building panels, portable buildings, swimmingpools, floor grating, doors, satellite dishes

Marine—Ski boats, fishing boats, sail boats,yachts, personal water craft, canoes, kayaks,docks

Corrosion—Tanks, processing vessels, pipes,fans, pollution control equipment, scrubbers

Transportation—Automobile body panels andstructural components, truck hoods and caps,trailer sidewalls, RV sidewalls, train seating

Consumer—Sporting goods, hobby castings,decorative art,

Electrical—Appliance housings, circuit boards,insulating boards

This chapter offers a brief outline of the properties thatmake FRP such a useful material.

2. MECHANICAL PROPERTIES—Mechanicalproperties characterize the strength, stiffness,toughness, and other load-carrying capabilities ofmaterials. Typical tests used to characterize mechanicalproperties of FRP composites include tensile, flexure(bending), compression, and impact properties. Testmethods for determining these properties are describedin Appendix A.

Cured, neat or unreinforced, resins are glasslike innature and most are relatively brittle. The addition ofreinforcing fiber dramatically improves the mechanicalproperties. The use of reinforcing fiber also allows FRPcomposites to be anisotropic. This means that they canbe engineered to have different properties in differentdirections. The mechanical properties of steel,aluminum, and other structural materials are isotropic orhave the same properties in all directions. Theanisotropy of composites is achieved by selectiveorientation of reinforcing fibers. When the fibers areoriented in the direction of known stresses, the strengthof the reinforcement is used more efficiently, and betterperformance is achieved at a lighter weight.

For instance, less roving reinforcement, oriented parallelto a tensile load, is needed to carry the load than if a matwith random fibers were used. However, the mat may bemore efficient in an application where the loads are morerandom. Another way to illustrate the anisotropy anddesign flexibility of composites is to look at properties ofvarious product forms. A rod made of parallel glassroving strands can have a tensile strength of 150,000psi, whereas a spray up laminate (made of randomlyoriented, chopped glass fibers) may have a tensilestrength of 15,000 psi. A combination mat and wovenlaminate will have tensile and flexural strengths from30,000 to 50,000 psi.



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FRP COMPOSITES: General Properties of FRP CompositesCopyright 2008

MECHANICAL PROPERTIES continued:Another difference between composites and otherconstruction materials such as steel and aluminum ishow they react to an impact. When a steel or aluminumpanel is impacted at low forces no change occurs.Impacts at higher forces may cause a dent. If the impactforce is high enough, the impact may rupture the panel.FRP panels, when impacted, will show no change at lowforces, cracking at higher forces, and rupture if the forceis high enough. FPR has no yield point and as a resultdoes not dent.

Mineral fillers are used in some FRP applications tolower cost. Fillers increase the stiffness of FRP butdecrease strength. Temperature also affects mechanicalproperties. Like most materials, FRP becomes morebrittle in colder temperatures and more flexible inwarmer temperatures. Thermal performance of FRP isdiscussed in more detail below.

3. HARDNESS—Hardness of an FRP laminate is anindication of the type of resin matrix and/or the extent ofcure of the resin matrix. More rigid resins will give higherBarcol readings, while resilient and flexible resins willgive lower readings. The hardness of a resin matrixincreases as it cures. When the resin reaches itsmaximum hardness value it is completely cured and itsproperties are fully developed.

Hardness can be measured using a variety ofimpressors. The most common are the Shore D, Barcol935, and Barcol 934. These impressors are simplehandheld devices that use a needle and spring assemblyto register a reading on a dial gauge. For FRP, Shore Dand Barcol 935 impressors are used for softer materialsor during the early stages of cure. The Barcol 934impressor is used for advanced cure stages as well asfully cured materials. For typical FRP construction, aBarcol 934 Impressor should show a reading of 35 to 45when the resin matrix has cured.

Hardness of gel coat films of typical thicknesses cannotbe measured using these types of impressors. Theneedle fully penetrates the film and will read thehardness of the substrate beneath.

4. SPECIFIC GRAVITY—The specific gravity orrelative density of unfilled, FRP is low in relation to otherstructural materials. At typical resin-to-glass ratios thespecific gravity of FRP is approximately 1.7. Forcomparison the specific gravity of aluminum is

approximately 2.8 and steel is approximately 8.0.

The low specific gravity coupled with the design flexibilityof mechanical properties described above results in anextremely high strength-to-weight ratio for FRP.Strength-to-weight ratio is a significant factor in weight-sensitive applications such as aerospace andtransportation.

The use of fillers in FRP affects the specific gravity. Mostcommonly used fillers (calcium carbonate, calciumsulfate, alumina trihydrate) and clays increase thespecific gravity. However, light-weight fillers, such ashollow glass microspheres, are available that can lowerthe specific gravity of FRP.

5. THERMAL PERFORMANCE—FRP componentsare used in a number of elevated temperatureapplications, including under the hood applications in thetransportation industry as well as numerous applicationsin the corrosion and electronic industries. The thermalperformance of these components is largely determinedby the polymer matrix, both the type of resin matrix andthe component cure process. Isophthalic resins andmost vinyl ester resins have excellent thermalperformance. Orthophthalic resins generally have poorthermal performance. The same polymer matrix resincured at different temperatures can have differentthermal performance, with the material cured at lowertemperatures having lower thermal performance. This istrue until the maximum thermal performance of thepolymer is reached. Curing the polymer above thetemperature at which the maximum thermal performanceis reached will not result in any additional increase inperformance.

The limitation on use of FRP in structural applications atelevated temperatures is loss of modulus or stiffness.This loss of stiffness is typically gradual at lowertemperatures until the resin matrix polymer reaches apoint where it transitions from a glassy to a rubberystate. This transition is called the glass transitiontemperature, Tg. Typically composites are not used instructural or load-carrying applications where the partwill see extended exposure above the resin matrix Tg.However, composites are used above their Tg inelectrical or corrosion applications. Even fornonstructural applications the Tg or thermal performanceof the polymer can be an important factor. A part thathas been exposed to temperatures above its Tg can



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THERMAL PERFORMANCE continued:have diminished cosmetic appeal due to distortion, print,and other factors. Depending on the type of polymermatrix used, this can occur in dark-colored parts that arein the exposed to sunlight.

Tg can be measured by various methods. Two commonmethods are Differential Scanning Calorimetery (DSC)and Dynamic Mechanical Analysis (DMA). DSC is achemical measure of Tg. DSC measures Tg by detectingenergy absorption. A polymer needs to absorb energy togo through its glass transition just as ice needs to absorbenergy to melt into water.

DMA is a physical measure of Tg with the modulus of asample being measured versus temperature. The Tg isdetermined based on a significant loss of modulus orstiffness.

In both DSC and DMA, the transition of the polymer fromglassy to rubbery occurs over a range of temperatures.The Tg can be defined as the onset, midpoint or end ofthe transition. The most applicable measure dependsupon how the data will be used. However, for Tg resultsto be comparable, they must all be defined using thesame criteria.

Another measure of thermal performance that iscommonly used in the FRP industry is the heat distortiontemperature, HDT. HDT is defined by ASTM D648. It isthe temperature at which a sample deflects, 0.10 in.(0.25 mm) under a load of 0.264 ksi. HDT can be run onneat resin or composites samples. The sample must be0.5 inches wide by 4 inches long. Thickness of thesample can vary between 0.125 to 0.5 inches. HDTcannot be determined for most reinforced laminatessince they do not reach the required deflection at atemperature within the safe operation range for the testequipment.

While Tg and HDT are indicators of FRP usetemperatures, another consideration is the effect of long-term elevated temperature exposure. Long-termelevated temperature exposure can cause the polymerresin matrix to oxidize, making the resin matrixincreasingly brittle. This a concern in any applicationinvolving long-term elevated temperature exposure, butparticularly in electrical applications where impactresistance or flexibility are required in addition toinsulating properties. The long-term elevatedtemperature performance of FRP is evaluated by

thermal aging studies. In these studies FRP samples areexposed to a range of elevated temperatures for varyingintervals. Critical properties are then tested. Theseresults indicate whether the FRP sample is appropriatefor use at the temperature and for the duration requiredfor the application.

Two additional properties that are important forcharacterization of FRP thermal performance are thecoefficient of thermal expansion (CTE) and thermalconductivity. CTE is a measure of the dimensionalstability of materials versus temperature changes. Mostmaterials expand when heated and contract whencooled. An understanding of CTE is needed by partsdesigners to ensure that a part will fit in its assemblyover the application temperature range. CTE is also animportant consideration when dissimilar materials areused in the same part or mated together in assembly.Stresses created by differing expansion and contractionrates should be minimized. Mold designers need CTEinformation to ensure that parts built on the molds willhave the required dimensions.

Thermal conductivity is a measure of how rapidly heat istransferred into or out of a material. Thermal conductivityof FRP is low compared to metallic materials, makingFRP suitable for insulating applications. The relativelylow thermal conductivity of FRP also makes the surfacepleasing to the touch in hot or cold ambient conditions.

Both CTE and thermal conductivity of FRP varydepending on temperature, filler and reinforcementcontent, and reinforcement orientation. The obviouseffect of temperature on CTE is that materials contract incold temperatures and expand at warm temperatures.CTE and thermal conductivity behavior can also besignificantly different, depending on whether thetemperature is above or below the resin matrix Tg. Theaddition of filler and reinforcement generally reduces theCTE. This is especially true in dimensions in-plane orparallel to the reinforcement. The effect of reinforcementon CTE is much less in the dimension perpendicular tothe reinforcement, which is generally through thethickness of the FRP part.

6. CHEMICAL PROPERTIES—FRP components areused in many applications requiring chemical resistance.These include tanks, processing vessels, pipes, fans,pollution control equipment, and scrubbers. Thechemical resistance of FRP components is influenced by



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CHEMICAL PROPERTIES continued:both the resin matrix and the reinforcement. Polyesterand vinyl ester resins resist chemical degradation tovarying degrees. Isophthalic based resins have betterchemical resistance than orthophthalic resins. Vinyl esterresins are typically even better than isophthalics.

FRP components produced with isophthalic and vinylesters have good chemical resistance to weak caustics,strong acids, and non-polar solvents. Strong caustics,polar solvents such as ketones (acetone), and thosehaving chlorine (carbon tetrachloride and chloroform)rapidly attack FRP. These chemicals either reactchemically with the polymers or swell the layers of thepolymers to the point where they mechanically break(blisters). Use of glass fiber reinforcement generallydoes not improve corrosion resistance and, in somecases, reduces the performance. This is especially truein strong caustic environments because these chemicalscan attack and dissolve the glass. Surfacing materialssuch as veils are available to enhance FRP partcorrosion resistance.

The suitability of an FRP component for use in a specificcorrosion application depends on the type of chemical towhich the component will be exposed, the exposuretemperature, and the exposure duration. Resin matrixsuppliers provide a corrosion guide with specificrecommendations based on these factors for theirproducts. Typically, testing material sample coupons inthe actual environment and conditions is the bestmethod for choosing which resin will have the best long-term performance.

7. ELECTRICAL PROPERTIES—FRP componentsgenerally have excellent electrical properties and areused in a wide range of electrical applications. Electricalproperties of FRP components are affected by the typeof resin matrix, filler type and content, and glass content.Many electrical applications also require elevatedtemperature performance so the same types of resinsused in thermal applications are used in electricalapplications. These include isopthalics and vinyl esters.Dicyclopentiadiene resins are also used in electricalapplications. A unique property of FRP is that it iselectrically transparent. This is particularly useful in themanufacture of radomes, Doppler systems, etc. FRP canbe made to be electrically conductive through the use ofspecial fillers.

8. FIRE RESISTANCE—FRP components are used inmany applications requiring fire resistance. Theconstruction, transportation and consumer goodsmarkets generally require some resistance to burningand have limitations on smoke generation and smoketoxicity. FRP components can meet many of theserequirements. Some standards can be met by usingtypical FRP resins and reinforcements, but with filler,usually alumina trihydrate. Other standards require theuse of specialized FR resins. These resins typicallycontain a halogen such as bromine. The fire resistanceof FRP can be improved even further through the use ofadditives such as antimony oxide.

9. OPTICAL PROPERTIES—Most general purposepolyester fiberglass laminates are translucent, althoughup to 90 percent light transmission can be achieved in a1/16 inch to 1/8 inch FRP laminate through the use ofspecial resins and mat. Opaque laminates can be madeby incorporating pigments and fillers in the resin. Colorcan be molded into the product so that painting isunnecessary.

10. WEATHERING PROPERTIES—The outdoorweathering properties of FRP are generally good.However, there is a certain susceptibility to ultravioletrays which require that ultra-violet absorber be specifiedfor translucent laminates. Normally, UV absorbers arenot required for gel coat because the pigments and fillersact as absorbers. In addition, all exposed laminatesshould either have a gel coat or a glass surfacing matspecified for the exposed surfaces to prevent fiber‘blooming’ or surface exposure of the fibers. For moreinformation on weathering see Part 4, Chapter VII FieldService.

11. POLYESTER SHRINKAGE—All FRP resin matricesshrink to varying degrees during cure. Reinforcementsand fillers are inert and do not shrink. Shrinkage is animportant consideration for mold building and must beaccounted for to ensure that parts will have the correctdimensions. (For more information on shrinkage andmold building see Part Eight Polyester Tooling.)Shrinkage of the resin matrix can also affect partcosmetics. Shrinkage of the resin matrix around fiberreinforcement can result in fiber print on the surface ofthe part. Shrinkage can also lead to part distortion. (Formore information on shrinkage and part cosmetics seePart 4 Chapter VII Field Service, Cosmetics).



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POLYESTER SHRINKAGE continued:The level of shrinkage of the overall FRP part dependson the type of resin matrix, cure process, the level offillers and reinforcements, and reinforcement orientation.FRP resin matrices shrink approximately 6 to 9% byvolume. Flexible resins generally shrink less than rigidresins. DCPD resins, although typically brittle, shrinkless than isophthalic or vinyl ester resins. Somespecialized resins, mainly used in tooling applications,have a low profile additive that reduces or eliminatesshrinkage. The shrinkage of FRP resin matrices alsodepends on the cure process and, specifically, the curetemperature. A resin cured in ambient conditions will notshrink as much as a resin cured at elevatedtemperature. The addition of filler and reinforcement to aresin matrix will reduce shrinkage. For reinforcement theshrinkage is less parallel to the reinforcement thanperpendicular to the reinforcement.

12. TECHNICAL DATA SHEETS—Resin, glass, filler,and other suppliers to the FRP industry provide technicaldata sheets for their products. These data sheetstypically include properties of these products as-suppliedand when used to fabricate an FRP part. FRP partmanufacturers often use these data sheets to compareproperties of one manufacturer’s product to another andmake material selections. However, caution must beexercised when comparing properties between differentmanufacturer’s data sheets. Subtle differences in testingprocedures can have a significant effect on properties.

In general, most manufacturers report the properties ofproducts measured using industry standard test methodssuch as those published by ASTM. These methodsspecify specimen preparation and testing procedures.However, within the test method guidelines variationsare allowed in the construction of the samples. Forexample, ASTM methods for testing resin castings andFRP laminates do not specify curing conditions that cansignificantly affect the resin casting and laminateproperties.

CCP participated in a double-blind, round-robin studywhere liquid samples of five competitors’ resins wereprovided to one another. Each company made castingsand laminates based on their own protocols for followingASTM methods. Then, each company ran physicalproperties and reported results. In general, relativeperformance differences between the materials werediscernible by all laboratories involved. In addition, incomparison of results for any given material, it wasobserved that some laboratories tend to report higherphysical properties than others.

Therefore, comparing physical properties as listed ondata sheets can lead to incorrect assumptions that onematerial is better than another. It is advisable to prepareand run side-by-side samples on the same piece ofequipment in the same laboratory. This will narrow thenumber of variances and yield numbers that can becompared. In general, data sheets should only be usedas general guidelines for suitability of a material for agiven application, and to compare materialsmanufactured by a single supplier.



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FRP COMPOSITES: Fabrication of FRP Composites

Composites

Applications Guide

Part Three, Chapter IVCopyright 2008

In This ChapterChapter I: Introduction

Chapter II: Process Descriptions

Chapter III: Process Selection

1. INTRODUCTION—Fiber reinforcedplastics can be fabricated using a number ofprocesses. Some examples are as follows:• Hand lay-up lamination• Spray-up lamination• Continuous lamination• Resin transfer molding and numerousvariations of this process• Infusion• Pultrusion• Fiber placement• Spin casting• Filament winding• Compression molding• Injection moldingThis book will not cover each of these processesin depth. However, three main categories ofthese processes will be examined further. Thesecategories are:• Open molding• Low volume closed molding• Compression moldingA brief description of each of these processcategories follows. Table 1 shows a comparisonof the major features of each category.2. PROCESS DESCRIPTIONS

A. Open Molding—Open molding is thesimplest and most widely used processto produce FRP parts. Open molding isdone in ambient shop conditions. Themold itself is generally fabricated fromFRP and is one-sided. It can be male(part is molded onto) or female (part ismolded into). The cosmetic surface of

the part is fabricated next to the mold.The back side of the mold is open.In contrast to many other fabricationprocesses where the exterior coating isapplied after the main structure of thepart has been built, open mold partsare built from the exterior to theinterior. The first step in open moldingis to apply the gel coat (the exteriorcoating of the part) to the mold. Theremaining layers of the laminatedesign, which will include some but notall of the following, back the gel coat:

1) Barrier Coat—An additionalcoating that is applied behind thegel coat. A barrier coat improvespart cosmetics, reduces cracking,and improves osmotic blisterresistance in marine parts.2) Skin Laminate—A relativelythin glass fiber reinforced laminatefabricated behind the gel coat. Skinlaminates improve cosmetics andosmotic blister resistance.3) Print Blocker—A sprayablesyntactic foam material usedbehind a skin coat to improvelaminate cosmetics.4) Coring Materials—Lightweight materials used to build partthickness and stiffness withoutadding weight.5) Bulk Laminate—The mainportion of the laminate thatprovides most of the structuralproperties.



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Copyright 2008

Table 1. PROCESS COMPARISON

Part Characteristic Open Molding Low VolumeClosed Molding

Compression Molding

Maximum Part Size Any Size Any Size Up to 100 Square Feet

Factors Limiting PartSize

Mold and PartHandling

Mold and Part Handling Press Size

Part Surface One Side Two-Sided, Smooth orTextured

Two-Sided, Smooth or Textured

Part to PartConsistency

Fair Good to Excellent Excellent

Cross Section CompletelyVariable

Better if Uniform Easily Varied

Number of Parts PerYear

<1000 <10,000 >5,000

Parts Per 8-Hour ShiftPer Mold

1-2 16-90 100-500

Mold Construction Composite Aluminum Nickel Shell,or Composite

Chrome Plated Tool Steel

Mold Lead Time 2-4 Weeks 4-8 Weeks 16 Weeks or More

Tons of Composite PerTons of Emissions

371 135-16302 135-16302

1. Numbers taken from unified emissions factors; 35percent styrene content resin; mechanical non-atomized application; and 30 percent fiberglass.

2. Numbers taken from EPA AP-42 emission factor;35 percent styrene content resin; compound paste(25 to 100 percent resin); and 30 percentfiberglass.



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Copyright 2008

Glass fiber reinforcement used in skin and bulklaminates can be applied by hand lay-up orspray-up. Hand lay-up is used when applying rollgood reinforcements such as chopped strandmats and textile constructions that are stitchedor woven. Brushes, rollers, or wetout guns can beused to apply the resin.

Spray-up is used when the laminatereinforcement ischopped roving. Chopped roving and catalyzedresin are sprayed onto the lamination surfacewith a chopper gun. The glass is wet out andcompacted with lamination rollers. Hand lay-upand spray-up can be combined within the samepart or laminate.

PROCESS DESCRIPTIONS continued:The part size for open molding is restricted onlyby part and mold handling considerations. Openmolding is labor intensive in comparison to someother processes. Part-to-part consistency isdependent on operator skill and is generallyvariable. Emissions from open mold processesare significant and are regulated by federalNESHAP standards and, in some cases, state andlocal regulations.More detailed information on open molding canbe found in Part Four of this book.B. Low Volume Closed Molding—Thecategory of low volume closed molding processesincludes processes in which liquid resin istransferred into a closed cavity mold containingreinforcing materials. Over time, many variationsof low volume closed molding processes haveevolved. Some examples are:

• Vacuum infusion• Seamann Composites Resin

Infusion Manufacturing Process (SCRIMP®)• Conventional RTM• Light RTM (shell laminate RTM)• Silicone bag RTM• Closed Cavity Bag Molding

(CCBM®)• Multiple Insert Tooling (MIT®) RTM

• Zero Injection Pressure (ZIP®)RTM.Parts fabricated using these processes may ormay not have gel coat on the exterior surface.For parts fabricated with gel coat, the gel coat isapplied to one half of the mold using the sametechniques as used for open molding. The mold isthen loaded with reinforcing materials and closed.Catalyzed resin is transferred into the mold. Afterthe part is sufficiently cured, the mold is openedand the part demolded.The part size for these processes is limited bymold and part handling considerations. Part-to-part consistency is better than with open moldingdue to less dependence on operator skill. Also,two-sided cosmetic parts can be produced.Emissions from these processes are stillregulated; however, they are much lower thanwith open molding due to the closed portion ofthe process. Emissions from the gel coatapplication, if used, are the same as for openmolding.More detailed information on low volume closedmolding can be found in Part Five of this book.C. Compression Molding—Compressionmolding is another closed molding process thatuses clamping force during mold closure to flow apremanufactured compound through a moldcavity. A hydraulic press generally provides theclamping force. Compression molds are generallymade from chrome-plated tool steel. Sheetmolding compound, bulk molding compound, andwet molding compound are examples ofpremanufactured compounds.

Figure 3/IV.1 - Trade Study Hatch Cover

If an external coating is needed on a compressionmolded part, it is generally post applied;



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Copyright 2008

however, in-mold coatings are available. Part sizeis limited by press platen size. Part-to-partconsistency is excellent. Emissions fromcompression molding are still regulated;however, they are much lower than with openmolding due to the closed nature of the process.More detailed information on compressionmolding can be found in Part Six of this book.3. PROCESS SELECTION—The best processto use for fabrication of a specific part may beobvious. However, when the best process is notobvious, process selection is best accomplishedthrough a process trade study.A process trade study involves comparing thepart fabrication costs and part performancefactors for a specific part fabricated by variousprocesses. Part fabrication costs include but arenot limited to equipment costs, tooling costs,material costs, and labor costs. Part performancefactors are dependent on the specific part beingstudied but can include weight, strengthrequirements, and appearance requirements.Emissions of Hazardous Air Pollutants (HAP) orother regulated materials vary by process andmay also factor into process selection. Anexample trade study follows.The subject part is from the deck of a run-aboutboat. It is a hinged hatch cover that providesaccess to an under-deck storage compartment orcooler. The step face features a non-skid profileon the external surface. The step face comprisesglass skins over foam-filled honeycomb core. Thepart measures 11 inches by 25 inches with a 1.5-inch tall perimeter flange. The design criteriainclude an impact of 300 pounds from a three-foot elevation. The part is shown in Figure 3/IV.1.Processes considered in the trade study wereopenmolding and several low volume closed moldingprocesses, including vacuum infusion, siliconebag RTM, light RTM, and conventional RTM.Equipment costs, tooling costs, material costs,and labor costs were calculated for each processon a per part basis. Costs are based on typicalvalues in the year 2008 and are presented as

relative costs with open molding at 100 partsproduced as the baseline.The number of parts to be produced varied from10 to 9,000. Parts were to be produced over athree-year time frame with an equal number ofparts per year. Process trade study cost resultsare shown in Figure 3/IV.2. The cost per partdecreases as the number of parts producedincreases. However, the amount of decreasedepends on the process, meaning that differentprocesses are the most cost-effective at differentproduction rates.Conventional RTM is not a cost-effective optionfor hatch cover production at production run sizesof less than 1,000 parts. For production run sizesgreater than 1,000 parts this process becomescompetitive with light RTM, but does not becomecheaper than light RTM, even at production runsizes of 9,000 parts, due to the need for a gel-coated surface.The cost comparison could be different for largeproduction runs of a nongel-coated part.While competitive with light RTM, silicone bagRTM is never the cost-effective process for hatchcover production. This is due to the cost of thematerials needed to fabricate the silicone bags.However, silicone bag RTM can be an excellentprocess selection for parts with closed contoursthat are not easily fabricated by other processes.

Light RTM is the low cost process for hatch coverproduction at production run sizes greater than100 parts.Vacuum infusion is competitive with openmolding as the low cost process for hatch coverproduction runs of less than 100 parts. At higherproduction rates vacuum infusion is not cost-effective due to the cost of the consumablematerials (vacuum bag film, sealant tape, etc.)needed for each part.Open molding is the low cost process for hatchcover production runs of less than 100 parts. Butis not cost-effective for production runs greaterthan 100 parts.



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Copyright 2008

Overall process trade study results, including partappearance, strength, cost and emissions, for thehatch cover are shown in Table 2.Use of a closed molding process reducesemissions by 50 percent in comparison to openmolding with low VOC materials. The emissionsdifferences as well differences in part appearancecould influence process selection for hatch coverproduction.This trade study is provided as an example of thetype of evaluation that can be done to make aninformed decision on process selection. Theconclusions reached are not valid for all parttypes, sizes, complexity, and specificcombinations of labor, material, and capital costs.



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Figure 3/IV.2 - Process Trade Study Cost Results

Table 2. COMPARISON OF RTM PROCESSES

Property OpenMolding

VacuumInfusion

Light RTM Silicone BagRTM

Conventional RTM

PartAppearance

Part backside isrough

Part backside is matte

Part backside issmooth

Part back sideis matte

Part back side issmooth

Strength Acceptable Comparableto openmolding

Comparableto openmolding

Comparableto openmolding

Comparable to openmolding

Cost EffectiveProductionRun Size

<100 parts <200 parts 100 to 9,000parts

100 to 9,000parts

>1,000 parts

Emissions 0.126lbs/part

0.064lbs/part

0.064lbs/part

0.064 lbs/part 0.064 lbs/part



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OPEN MOLDING: Introduction


Part Four, Chapter ICopyright 2008

In Part FourChapter I: Introduction

Chapter II: Conventional Gel Coat

Chapter III: Specialty Gel Coats

Chapter IV: Vinyl Ester Barrier Coats

Chapter V: Lamination

Chapter VI: Sprayable Print Blockers

Chapter VII: Field Service

Open molding is the most widely used process forfabrication of FRP parts. The basic open moldingprocess involves applying gel coat to a one-sided mold,and then backing the gel coat with the remainder of thelaminate design. Open molding is generally done inambient conditions. Some of the materials commonlyused in open molding are:

• Gel Coat—The exterior coating of the part, thegel coat serves several purposes. Duringmanufacturing, the gel coat protects the moldfrom abrasion and chemical attack. It alsoprovides a releasable coating. Aftermanufacture, the gel coat becomes the exteriorcosmetic coating of the part and also providesprotection against water exposure andweathering. Most, though not all, open-moldedparts are gel coated. Examples of nongel-coated, open-molded parts include spas,bathtubs, and shower stalls where acrylic orABS is used in place of gel coat as the exteriorcoating.

• Barrier Coat—An additional coating that isapplied behind the gel coat, the barrier coatimproves part cosmetics, reduces cracking, andimproves osmotic blister resistance in marineparts.

• Skin Laminate—A relatively thin glass fiber-reinforced laminate fabricated behind the gelcoat, the skin laminate is specially formulated tocure completely as a thin laminate and toimprove part cosmetics. Skin laminate resins arealso typically formulated with high performancepolyester or vinyl ester polymers to improveosmotic blister resistance.

• Print Blocker—A sprayable syntactic foammaterial, the print blocker is used behind a skinlaminate to improve laminate cosmetics.

• Coring Materials—These light-weight materialsare used to build part thickness and stiffnesswithout adding weight.

• Bulk Laminate—This component is the mainportion of the laminate that provides most of thestructural properties.

The following chapters cover the various gel coat andresin materials used in open molding, applicationtechniques, troubleshooting guidelines, and field serviceissues.



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OPEN MOLDING: IntroductionCopyright 2008



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OPEN MOLDING: Conventional Gel Coat—Materials


Part Four, Chapter II.1Copyright 2008


2. Materials

3. Quality Control

1. INTRODUCTION—A conventional gel coat is apigmented, polyester coating that is formulated for use inambient temperature, open mold processes. The gelcoat is applied to the mold surface and becomes anintegral part of the finished product. The gel coatprovides a durable, cosmetically appealing finish andalso protects the part from environmental exposure.

2. MATERIALS—Conventional gel coats areformulated from several components, including thepolymer, reactive monomer, pigments, fillers, thixotropicagents, promoters, inhibitors, and specialty additives.The specific materials and amounts significantly affectthe performance of the gel coat both in themanufacturing shop and in the part’s end application.

A. Polymer—Polyester polymers can have a widerange of properties, depending on the raw materials(acids and glycols) used to produce them. Allpolyester polymers have an unsaturated acidcomponent, typically maleic anhydride. Thisunsaturation in the polymer provides sites forreaction with the monomer, also known as cross-linking. Polyester polymers used in gel coats alsohave a saturated acid component. In some casesthe saturated acid has been orthophthalic acid, butthe most commonly used saturated acid isisophthalic. Polyester polymers containingorthophthalic acid have been used in gel coats forgeneral purpose applications. Polyester polymerscontaining isophthalic acids impart superiorweathering, water resistance, and chemicalresistance properties to the gel coat. (See PartThree, Chapter II, General Chemistry of FRPComposites for more information.)

B. Monomer—The monomer fulfills two roles in a

gel coat. The first role is to react and cross-link withthe reaction sites in the polymer to form a cross-linked thermoset material. Secondly, monomersreduce the viscosity of the gel coat to a workablelevel for application. Some common monomers usedin gel coats are styrene and methyl methacrylate(MMA). The amount and combination of thesemonomers affect the flash point, evaporation rate,reactivity of the system, weathering properties, andother characteristics. Regulations typically limit thetype and/or amount of monomers that can be usedin gel coats.

C. Fillers—Fillers are used to achieve certaincharacteristics of the gel coat and also influencespray properties. Fillers can influence the curedphysical properties of the gel coat, as well asresistance to water and other environments that maychange color or influence chalking. Commonly usedfillers are calcium carbonate, talc, and aluminumtrihydrate.

D. Thixotropic Agents—Gel coats are formulatedto be thixotropic, i.e., have a viscosity that isdependent on shear rate. A gel coat should have alow viscosity during spraying, which is a high shearoperation. Once deposited onto the mold and underlow shear, the gel coat should recover to a highviscosity to prevent sag. This thixotropic behavior isobtained through use of thixotropic agents. Thesematerials form a network with the polyester polymerthrough hydrogen bonding. During high shear thisnetwork breaks down and lowers the viscosity of thegel coat. After the high shear is completed, thenetwork reforms, or recovers, and the viscosity ofthe gel coat increases. The faster the rate ofrecovery the lower the risk of sag but the higher therisk of air entrapment.

The thixotropy of a gel coat is commonly determinedby measuring a low shear and a high shear viscosityof the product and calculating the ratio of these twovalues. The ratio value is reported as ThixotropicIndex (TI).



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OPEN MOLDING: Conventional Gel Coat—MaterialsCopyright 2008

Thixotropic Agents continued:Two major classes of thixotropic agents are fumedsilica and organoclays. Other thixotropic agentscalled synergists are used to further enhance thethixotropic network.

E. Promoters and Inhibitors—The types andlevels of promoters and inhibitors used in gel coatsdetermine the cure behavior including gel time andlay-up time. The gel time must be long enough toallow for spraying, air release and leveling. The lay-up time must be short enough to meet desiredproduction rates. Short gel times reduce thepossibility of under cure issues, includingalligatoring, caused by styrene solubility of the gelcoat. Short cures can also improve gloss, but aremore prone to prerelease. Most gel coats are curedunder ambient conditions with peroxide initiators(catalysts). Promoters, also called accelerators, splitthe peroxide into free radicals. These free radicalsattack the unsaturation sites in the polyesterpolymer, preparing them for reaction with themonomer. The most common promoter used in gelcoats is cobalt. However, cobalt by itself does nottypically result in proper cure behavior. Othermaterials called co-promoters are used to furtherenhance the cure behavior. Co-promoters enhancethe ability of promoters to split the peroxide catalystinto free radicals. They are very effective inshortening the gel time and accelerating the curerate. Inhibitors provide shelf life stability to gel coat,as well as help control the gel time. Free radicalsgenerated in the gel coat during storage or afteraddition of peroxide react preferentially with theinhibitors. Only after all the inhibitors are consumeddoes the cross-linking or curing process begin.

F. Specialty Additives—In addition to the abovematerials, a number of other additives can be usedin gel coat formulations to effect properties. Someexamples include air release agents to reduceporosity and UV absorbers and light stabilizers forweathering performance.

G. Pigments—Pigments are used to produce gelcoats in a wide variety of colors. The specificpigments used determine not only the color of thegel coat and fabricated part, but also significantlyaffect performance characteristics of the coating.

Pigment type and concentration affect the hidingcapacity (opacity) of the gel coat. Bright yellows,oranges, reds and dark blues will have slightly lesshiding capacity than pastels. The high pigment loadsnecessary to achieve better hide with these brightcolors can cause spray and cure problems. Carefulpigment selection can also slow chalking that occurswith outdoor exposure and provide an abrasionresistant coating that can be readily cleaned, waxedand buffed to a high gloss.

The most commonly used pigment in gel coats istitanium dioxide. Titanium dioxide is the primarypigment in white gel coats and is also used incombination with other pigments in non-white colors.

3. QUALITY CONTROL—When producing gel coats,manufacturers run a variety of quality control tests toensure that the product being produced will meet theend-users needs. Standard quality control tests for gelcoat are gel time, viscosity, Thixotropic Index, weight pergallon, color, sag, porosity, pigment separation and hide.Each of these tests is briefly described below.

A. Gel time—The gel time is a measure of the timerequired from catalyzation for the gel coat to turnfrom a liquid to a solid. With few exceptions, gel timetests are run at 77ºF (25ºC) on a 100 gram sampleof gel coat using 1.8 percent of a standard 9.0percent active oxygen MEKP initiator. The 100 grammass or cup gel is a standard in the FRP industry forcharacterizing gel coat cure. These parameters arevaluable to the resin manufacturer when producingthe product and to the end-user for verifying that theproduct will be suitable for use in their process.However, it is important to the fabricator tounderstand that the reaction that takes place in 100gram mass will not correspond to the reactionobserved in the actual application. Specifically, thegel of the 100 gram mass is faster and reaches amuch higher exotherm temperature than the sprayedfilm.

B. Viscosity—Viscosity is a measure of how aliquid material flows when a force is applied. Thehigher the viscosity of the material, the moreresistant the material is to flow. For example, waterhas a lower viscosity or flows more easily thanmolasses. Gel coat viscosity is typically measuredusing a Brookfield RV model viscometer with a #4



Page 2 of 5


Viscosity continued:spindle at 4 RPM. The spindle speed will varydepending on the gel coat. Viscosity is measured at77ºF (25ºC) and reported in centipoise (cps).

C. Thixotropic (Thix) Index—The Thix Indexindicates the dependence of the gel coat’s viscosityon shear rate. (See Section 1.D on the precedingpage on thixotropic agents.) It is typically reported asthe ratio of the Brookfield viscosity readings with anRVF #4 spindle at two (2) and twenty (20) RPM at77ºF (25ºC).

D. Weight per gallon—The weight per gallon isthe density of the gel coat and is reported in poundsper gallon. It is measured at 77ºF (25ºC).

E. Color, Sag, Porosity, Pigment Separation—Acolor panel is prepared for each batch of gel coatand compared against a color standard. (SeeChapter II.2 in this part of the manual for adiscussion of color.) This color panel is also used tovisually check sag resistance, porosity/pinholes, andpigment/resin separation.

F. Hide—Hide is evaluated by drawing down thegel coat sample on a gray and white patternedpaper. The draw down bar is tapered creating avariable gel coat film thickness. The gel coat film isvisually inspected to determine the point at whichthe pattern on the paper is no longer visible. The gelcoat thickness at this point is measured using a milgauge (this mil gauge thickness is the hide). Thethickness required for hide is generally less than therecommended gel coat thickness.

Quality control values typically reported on a certificateof analysis (COA) include the gel time, viscosity, ThixIndex, and weight per gallon. See Appendix A foradditional information on quality-control testingprocedures.



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OPEN MOLDING: Conventional Gel Coat—Color




2. Color in General

3. Describing Colors

4. Judging Color Matches

5. Instrumentation

6. Determination

7. Color Matching Techniques

8. Tinting

1. INTRODUCTION—This chapter deals with color andpolyester gel coats. It includes a brief description ofcolor, how it is judged and by what standards, tinting,and color matching (visually and instrumentally).

2. COLOR IN GENERAL—Color is all around. Itdirectly or indirectly affects an individual’s interpretationof everything he or she sees. Color is used to please,motivate, sell, amuse, and instruct. It is used to judge thefreshness of an apple or a piece of meat. It can affecthow people feel; consider the difference between abright sunny day, and one that is gray and overcast. Thehuman eye can differentiate among 300 colors frommemory and about 10 million colors when placed side byside; yet color is very hard to define or explain.

Color is a psycho-physical reaction to how the mindinterprets what is seen. Since color is an interpretationby the brain, the ability to see color differences islearned. It is subject to the whims of the observer andhis or her past experiences. If several people are showna yellow-green panel and are asked to name the color,there will be several different responses. Some will saythe color is green, while an artist may describe it aschartreuse, and a farmer may say ‘John Deere green.’

Since light and color are sensed by the eye, thecondition of the eye is important. Naturally, if a person iscolor-blind (partially or fully), there will be problems withcolor distinctions. Anything that affects vision (e.g.,

fatigue, eye glasses, lighting, inflammation, alcohol, ordisease) will affect color perception. As a person ages,there is less sensitivity to violet and blue light due to abuild up of yellow pigment in the eye.

Texture and gloss of the substrate will also affect colorperception. These will cause a color change with viewingangle. In general, the glossier something is, the darkerand more saturated (less gray) it appears. An exampleof this may be seen by sanding an area of a dark gel-coated panel. The sanded area and sanding dust willappear to be whiter than the unsanded panel. This effectis due to how light is reflected from that roughened area.

The type and amount of light under which an object isviewed affects its color. If sunlight is passed through aprism, a rainbow of colors appears. This display of coloris the visible spectrum. Visible light is measured bywavelengths using ‘nanometers’ as the unit of measure.A nanometer is equal to one billionth of a meter. Violet is400 to 430 nanometers; blue—430 to 485; green—485to 560; yellow—560 to 585; orange—585 to 610; andred—610 to 700. Wavelengths of light outside this rangeare not seen by the human eye. As each wavelengthgroup has its own energy and as light passes throughthe prism or raindrops, the groups are separated due toenergy differences.

When all the light is reflected back from a panel, thecolor is called ‘white.’ If the panel surface absorbs all thelight, it is called ‘black.’ If the panel absorbs all thewavelengths except the red length, it is called ‘red.’ But ifa red light is shined on a white panel, the onlywavelength of light it can reflect is red and the panelappears to be red.

To review a color properly requires a light source whichhas all the visible wavelengths of light. North daylight isconsidered the classic standard for color viewing. Buteven daylight changes from day to day. Artificial lightsare strong or different in one area. Tungsten A lights arestrong in the yellow-red range, giving a yellow-red castto an object. Incandescents are rich in red. Mercuryvapor is deficient in red, giving a greener cast to objects.



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OPEN MOLDING: Conventional Gel Coat—ColorCopyright 2008

COLOR IN GENERAL continued:This difference in light sources accounts for why onemay buy an item of a particular color in a store and then,on unwrapping it at home, discover it is quite a differentcolor. The color has not changed, but the light sourcehas. This can even happen when a color standard istaken to the store. The coloring agents (pigments) in thestandard and the final product may be different. This isespecially true when the standard is made of a differentsubstance (paint versus cloth, plastic versus paint). Eachpigment or dye has unique absorption and reflectioncharacteristics in the visible light spectrum and isdependent upon the light source as well. For this reason,one type of yellow pigment used in a color chip appearsdifferent than another yellow pigment used on a chair.They may not always appear to be the same colordepending on the light. Under one light source (perhapsin a store), the yellows may appear to be the same color,but in another type of light, they will appear to bedifferent (the paint may appear redder, the chairgreener). This is called color flip, or metamerism. Theamount of light also affects color. It is difficult todetermine color differences in a darkened room or in avery bright light.

Color is quantified instrumentally using three pairs ofantagonistic color contrasts. The contrast pairs are:

• Light-dark• Red-green• Yellow-blue

Using these pairs, the eye determines all colors. Whensomeone is color-blind, he or she usually cannot make adistinction in one or more of these areas. There are anumber of color-blindness tests (Holmgen, Wood Test,Nagel Charts, Stilling, and Ishihara), but these are notfoolproof. Usually, a color-blind person is revealed byerrors in color work.

3. DESCRIBING COLORS—Three terms must beused to describe any color:

• Hue• Chroma• Contrast

It must be assumed that the observer recognizes theprimary colors—red, blue and yellow. These are hues.Chroma refers to brightness or intensity of a particularcolor, and contrast refers to lightness or darkness.

4. JUDGING COLOR MATCHES AND STANDARDS

A. Criteria—Judging a color match is like any othertest: All variables must be held constant except theobject being tested. Or, in simpler terms, one wantsto judge colors under the same conditions and usingthe same standard.

B. A number of things can affect color. Thesemust be held constant in order to judge color. Theseitems are:

1) The Observer—The person who is judgingcolor must be free from any type of colorblindness. Many times the opinion of two orthree people is used as a safeguard.Instrument type and accuracy will influencemeasurement values. See Section 5–Instrumentation in this chapter for details.

2) The Light Source—The type of light affectsthe color. Therefore, the best judgment ofcolor is made when two or more differenttypes of light are used for viewing. Theclassic standard is north light. To use thismethod, the tester stands with his or herback to a north light, holding the panels tobe judged out in front at a 135 degree angle.The color is checked again under anincandescent or fluorescent light. Whencolor judgments are critical, a light booth isused. These booths have multiple lightsources—typically, daylight and horizon(yellowish) are included.

3) Background—Color is influenced by thebackground or surroundings. Best colorjudgments are made when the backgroundis a neutral dull gray. Color booths have alight gray viewing background.

4) Viewing Angle—The standard and test panelshould be positioned side-by-side at thesame angle. Best color viewing is at 135degrees. Best viewing of gloss is at thesame, but opposite, angle from the lightsource. Switch the panels from side to sideto prevent bias.

5) Size and Texture—The object size affectscolor perception. A larger area observedprovides a broader color sample. Thesmaller the area observed, the more limited



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JUDGING COLOR MATCHES AND STANDARDScontinued:

or restricted the perception. Texture andgloss also affect color perception. Highergloss is perceived as darker, while lowergloss appears lighter.

6) Temperature and Humidity—Pigments aresubject to color change depending uponconditions. When temperature alters thecolor, then the object is considered to be‘thermo-chromatic.’

7) Standard—The choice of a standard is veryimportant. It should:

• Not change on aging• Be uniform in color• Be of the same material as the test

panel• Measure at least three inches by five

inchesC. There are three types of standards:

1) Master Standards—This type is used to setthe original color. It is stored in the darkwhen not in use, and should be refrigeratedto prevent color change. It is only used as afinal color check or as a reference for whatthe absolute color should be.

2) Working Standards—These standards arethe ones which are used in the preliminarycomparison for color. They can be sectionsof the master standard or the agreed upon‘perfect match.’ As these standards arehandled daily, exposed to light and generalwear, they will drift in color. These standardsmust be checked periodically against themaster and discarded when they drift too farfrom the original.

3) Electronic Standards—These standards arespectral measurements by instrument storedon a color computer. Master and workingstandards can be replaced. Color drift islimited by the instrument accuracy.

Once the standard method of viewing and variancesare established, there are still a few things toremember:

• When a new standard is selected, allholders of the old one must also change

the standard at the same time.

• Also, the supplier must be providedadequate time and a target date toswitch over to the new standard. Whencomparing batch to batch, always referto the standard. It is possible to obtain abatch on the light side of the standard(good match) and a second batch on thedark side of the standard (good match),but the batches might be unacceptablematches to each other.

5. INSTRUMENTATION—Although there areinstruments to help in color matching and judgments,these will not solve color problems. There are two typesof instruments: those that measure color magnitudedifferences (tristimulus colorimeter) and those thatmeasure color wavelength differences(spectrophotometer). Each instrument has its ownlimitations. They are still dependent on a consistentreference standard and a good test panel with the samegloss as the standard.

If the standard used to set the reference point is mottled(not uniform color) or distorted, the reference point willvary. If the test panel is distorted or different in gloss, itwill provide different readings in different viewing areas.In some wavelengths of color, one instrument will bemore accurate than others. Usually, dark colors aremore difficult. Some of these instruments include:

A. The Colorimeter—It views color differencesusing three color filters in groups of wavelengths. Astandard is placed under a view port and themachine reference points are set. Then the sampleis inserted and color difference is read from the fourfollowing readings:

dL (- is dark, + is light)da (- is green. + is red)db (- is blue, + is yellow)DE Total color difference

This instrument is good for determining in whichdirection a batch is off, and can be used for tinting.



Page 3 of 8


B. Spectrophotometer coupled with a computersystem—These newer and more expensivesystems provide more (and more useful) information.These instruments use a monochromator thatmeasures wavelength by wavelength, detecting theamount of light reflected by the standard versus thetest sample. Multiple light sources are used with fourreadings for each light as follows:

DL (- is dark, + is light)DCRG (- is green, + is red)DCYB (- is blue, + is yellow)DE Total color difference

These readings can be given in various colorsystems, such as MacAdam, CMC, CIE, or Hunterunits. One MacAdam unit is normally considered asthe minimum amount of color difference to bedetectable by the normal human eye. Besidesmeasuring color differences, this instrument will spotmetamerism (color differences based on lightingconditions) and aid in formulating and tinting batchesby selecting pigments for the best possible colormatch.

NOTE: These instruments are helpful, but the finaldecision on suitability of a color match shouldalways be made with the trained eye. Theseinstruments can produce numbers that indicate agood match, while visually it is not, or the match mayappear closer than the numbers indicate.

6. DETERMINATION—Now that the conditions are setfor viewing a color match, the hardest part involvesjudging the color. Does the test panel match thestandard or is it just an acceptable match? It is nearlyimpossible to make a product over and over so that eachbatch perfectly matches the standard.

It can be a challenge to set up allowable limits of colordifferences. To set up allowable color variances, firstdetermine how important color differences are. If thefinal product is sold as one item part and will rarely benext to another part of the same color, a wider varianceis more acceptable. If parts are used side-by-side orneed to match the color of another part, the variance incolor must be kept at a minimum. Usually, reasonableallowable color variations are set by trial and error andare not absolute. Keeping samples of acceptablebatches is one way to get a feel for allowable variance.

NOTE: Tighter color control will take more time andtherefore cost more.

In comparing color, there are two possible approaches:

• Visual—subjective, but usually the finaldetermining method.

• Instrumentation—quantifiable and easilydefined, but may be misleading if numericvalues are not properly interpreted.

Before covering the specifics of these individualapproaches of color comparison, some generalconsiderations must be given:

A. Rating system—Whether comparing the colorwith the unaided eye or by instrumentation, a ratingsystem is useful. (At CCP, color matches are ratedas AA, A, B, or C in quality.)

B. Color standards made with gel coatproducts—These standards can drift in color.Whites and off-whites can drift the most. To slow thiscolor drift, storing the gel coat standards in a freezeris recommended. The life of a standard may beextended to a year or more by this method.

C. Sample—For this discussion, ‘sample’ refers toa cured gel coat film. This film may be laminated orsimply ‘taped’ (gel coat film backed with maskingtape). The preparation of the sample is important tostandardize. Factors which influence the final colorare:

1) Agitation—That is the amount of mixing priorto application and the application method(drawdown, conventional spray, airlessspray, etc.).

2) Catalyst Level—The gel coat color typicallybe-comes darker and greener with morecatalyst.

3) Curing—The gel coat color will differdepending on the temperature at which it iscured as well as the cure time. Higher curingtemperatures may make the color darkerand yellowing. NOTE: Gel coat castingsmade for color comparisons are not reliablesince the exotherm of a gel coat in a massmay cause color variations.

4) Thickness of the gel coat film and type ofsubstrate—Thin gel coat films will present



Page 4 of 8


DETERMINATION continued:different color appearances depending uponthe color of the substrate. Gel coats typicallywill hide at 15 mils cured film thickness.Bright colors, such as reds and yellows,typically require 20 to 25 mils cured filmthickness for appropriate coverage. Thinnerfilms might allow the substrate to showthrough the gel coat film, affecting theperceived color. Tape-backed samplesmight read lighter than laminated samples.

5) Low-gloss samples will appear lighter. andback of a gel coat film. Color comparison ofthe gel coat versus the standard should beof the front or mold side. Obtaining the samecolor on a respray of a particular gel coat islimited by the above factors. Generally, thevariations are hardly noticeable (if at all) tothe unaided eye; however, for tight colorcontrol, all factors must be considered.

D. Visual comparisons—Visual comparisons are,by far, the most common method. No matter whatinstrumental readings may show, the color matchmust ‘look’ good. NOTE: Generally, three-inch byfive-inch color panels are compared under astandard light source in a light booth. Panels areplaced side-by-side at a 135 degree angle. Viewingcolors under more than one light source is importantin identifying the metamerism.

Visual comparisons are usually the final determiningfactor in acceptance of a color match. The lightsource, background, and observer influence thedecision. There is no way to eliminate thesubjectiveness created by the observer; however,the other factors can be standardized.

E. Instrument comparisons—CCP uses onlyhigh-accuracy spectrophotometers. With this type ofequipment, CCP can accurately correlate datagenerated from one instrument to another and fromone day to another. Without this type of equipment,accurate color comparisons against stored orabsolute values are not possible. Also, because ofthe variation of instruments, coordinating thereadings of two different models of instruments(even from the same manufacturer) is not possiblewhen Class A color matches are desired.

CAUTION: Taking a single instrumental readingof a large panel may not provide a representativereading of the overall panel. When possible, CCPsuggests taking multiple readings of thestandard and sample, using the average colorvalues for determining color differences.

7. COLOR MATCHING TECHNIQUES—CCP believesthe following method of color matching provides themost accurate and reproducible production colormatching in the industry. The electronically stored valueprovides a consistent standard regardless of the CCPmanufacturing site, and eliminates the inherent color driftof ‘master standards’ that are based on FRP polyesters(even under freezer storage), or from damage tostandards due to day-to-day handling.

CCP does not recommend matching to the ‘last batch’panel or by side-by-side drawdown since thesetechniques lead to a color drift from the standard. This isparticularly true for whites and off-whites where there isa natural tendency of the observer to approve thecurrent batch on the light and clean (red and yellow) sideof the ‘last batch.’ There is also a natural shift of color inthe container for whites and off-whites to the light andclean side due to the interaction of promoters andfillers/thixotropes over time.

A. Equipment—Datacolor’s 600 seriesspectrophoto-meter with formulated correctionsoftware.NOTE: Sample preparations using systemingredients are required. Accuracy is critical tosuccessful formulation and correction.

B. Calibration/verification—Calibrate instrumentat initial setup, after repair, or at any time whereoutput is in question. Individual instruments areverified by a ‘color tiles’ test on a weekly basis.Further instrument accuracy can be confirmed by aBCRA (British Ceramic Research Association) colortiles test.

C. Color standards—Electronically stored spectro-photometric values as determined on a masterinstrument maintained in CCP’s Kansas CityCorporate Research facility. These electronicallystored values are shared among all CCP plantsthrough a common electronic network.



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D. Color sample preparation—Catalyze andspray out onto a freshly waxed glass mold. Cure for30 to 40 minutes at 150°F (66°C) . Apply maskingtape to the back side and demold. (Note that moldpreparation, the amount of catalyst added, spraying,and cure cycle have a dramatic influence on color.These parameters must be controlled carefully.)

E. Tolerances and measurement methods—Color readings are Specular Included (eliminatesinfluence of gloss and distortion of the color sample)and color differences are computed by the CMC(1.00:1.00) method.

Typical color match tolerance is 0.30 DE (barelydetectable visually). Other DE tolerances are useddepending on product, color, and customerrequirements. (A visual reference to the ‘last batch’or ‘a master standard’ may also be required as anadditional precautionary step.)

8. TINTING—At times, tinting in the field is required (forexample, for a part made several years previously whichmust now be patched, or for a one-time small job). To dowell, and to do quickly, tinting requires skill andexperience. CCP normally does not recommend tintingin the field, but for those who must do this, there are afew rules:

A. Use only pigment concentrates designed forpolyester.

B. Tint at least one-half gallon of gel coat at atime. It is much harder to work with small quantities.

C. Make small additions, mixing well and scrapingdown the sides of the container between adds.These additions should get smaller as the colorcomes in closer.

D. To determine the undertone of a concentrate,it is helpful to check that concentrate in white.

E. Obtain the basic color shade first (i.e., yellow,blue), then look for shade differences (i.e., redder orgreener, etc.)

F. If the match is not good at the start, put a wetspot of the batch on or next to the wet solid part. Asthe color gets closer, it will be necessary to switch tocatalyzed sprayouts because some colors changefrom wet to cured.

G. Once a match is made, record what pigmentsand amounts were used to obtain the color, in caseit has to be matched again. Listed below are theapproximate effects of adding the following pigmentconcentrates:

COLORANT COLOR EFFECT

PRIMARY SECONDARY

Titanium Dioxide or TiO2 Lighter Chalky in dark colors

Carbon Black Darker Gray in pastels

Phthalo Green Green Darker

Phthalo Blue Blue Darker

Iron Oxide Red Red Darker; pink in pastels

Ferrite Yellow Yellow Red



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Page 8 of 8

OPEN MOLDING: Conventional Gel Coat—Spray Equipment




2. Equipment Needed for Operation of a Spray Gun

3. General Considerations for Selection of Spray

Equipment

4. Description of Types of Spray Equipment

5. Spraying MACT Compliant (MC) Gel Coats with

Air-Assist Airless and Non-Atomized Equipment

6. Spraying with Non-Atomized Application

Technology (NAT) Equipment

7. Spraying MC Gel Coats Through Standard Air-

Assist Airless or Airless Equipment

8. Spray System Selection

9. Spray Selection and Settings

10. Calibration

11. Cleanup Procedures

12. Maintenance

13. Equipment Troubleshooting

14. Additional Information on Equipment

15. Equipment Suppliers

1. INTRODUCTION—The application of gel coat is acritical operation with its success dependent on thematerial, the equipment, and the operator. These are thethree main factors that determine the quality of parts,none of which can be overlooked or taken for granted.

The information compiled in this chapter is designed tohelp in the selection of spray equipment and todetermine initial starting settings. Because each shop isdifferent, these are general recommendations. The plant,the part, production speed, and the spray person willultimately determine the exact equipment, spray guns,and settings to be used. Obtain and read sprayequipment manufacturer manuals, parts lists, and safetyguides before using.

2. EQUIPMENT NEEDED FOR OPERATION OF ASPRAY GUN—To use a spray gun efficiently and safely,the following items should be the proper size and type,and be in proper working condition.

A. Ventilation—A spray booth is required to spraypolyester resins and gel coats. The size and the airmakeup will depend on the size and the air makeupof the parts being sprayed. General rules of thumbinclude:

1) Measurement of the largest part to besprayed.a) Height—add minimum of 2 feet.b) Width—add minimum of 4 feet.c) Length—add minimum of 6 feet.

2) CFM requirements are figured with thefollowing formula: width x height x 125. Theaverage air velocity required to expel fumesis 125 FPM.

3) Disposable filters only.4) Contact equipment supplier for

recommendations.

B. Lights and electrical switches—Explosionproof.

C. Manifolds and regulators1) Manifolds and regulators should have a

CFM capacity at least 1½ times the sumrequired by the equipment they supply.

2) The atomizing air should be on a separateregulator with a water trap.

3) All gauges must be readable and workingand should be permanently attached.

D. Moisture and oil traps—Moisture and oil trapsshould be installed and drained daily on all air linesat the spray booth. These not only keepcontaminants out of gel coats but also protect andlengthen spray equipment life. Do not install within25 feet of compressor. Traps should be located atthe lowest point in the line.



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OPEN MOLDING: Conventional Gel Coat—Spray EquipmentCopyright 2008

E. Band heaters—CCP does not recommendusing band heaters because of the possibility ofcreating localized heat spots, which will cause thematerial to gel solid.

F. Quick disconnect—If quick disconnects areused, use the largest size possible. Quickdisconnects can reduce the volume of air and fluidsthat pass through them. If a quick disconnect is usedon fluid lines, a ball valve may be installed in front ofit to help reduce leaking.

Table of Air Pressure Drop

Size of Air

Hose

Air Pressure Drop at

Spray Gun in Lbs.

(Inside Diameter) 20 Ft.

Length

25 Ft.

Length

50 Ft.

Length

1/4 inch

At 60 lbs. pressure 16¾ 19 31

At 70 lbs. pressure 19½ 22½ 34

At 80 lbs. pressure 22½ 25½ 37

5/16 inch

At 60 lbs. pressure 5½ 6 11½

At 70 lbs. pressure 6¾ 7¾ 13

At 80 lbs. pressure 8 8¾ 14½

G. Hoses—Hoses should only be used for deliveryof air and fluid from a regulator on a main air line orfluid pump to the gun. The length should not exceed50 feet (normally only 25).Hoses should be large enough to deliver the propervolume of material at the proper pressure that thegun demands when the trigger is pulled. A pressuredrop will always occur between the source of the airor fluid and the exit.

NOTE: Catalyst and airless hoses are made ofspecial material—consult the equipmentmanufacturer about replacement parts.

H. Main air lines—The main air lines should bemade of steel pipe and should meet the followingrequirements:

1) Be large enough to supply air to all facilitieswith no CFM or pressure drop.

2) Be capable of supplying the pressure andvolume of air to run all air-poweredequipment used at the same time.

3) Be laid out as straight as possible.4) Have minimal fittings.5) Have drop lines that come off the top of

main air lines.6) Have slant lines to drain any water to one

end, with a low-end drain.7) Have air lines off drop lines that are not

taken off the end but at least 12 inchesabove. A drain valve should be on thebottom.

Air lines should be pressure tested for leaks yearly.

MINIMUM PIPE SIZE RECOMMENDATIONS

COMPRESSING

OUTFIT

MAIN AIR LINE

Size(HP)

Capacity(CFM)

Length Size

3 & 5 12 to 20 Up to 200 ft.Over 200 ft.

¾ inch1 inch

5 to 10 20 to 40 Up to 100 ft.Over 100 to 200ft.Over 200 ft.

¾ inch1 inch1 ¼ inch

CFMs REQUIRED FOR VARIOUS AIR TOOLS

TOOL CFM REQUIRED

Air motor 4

Polisher 2

Sander 5

Dusting gun 2.5

Nailers & staplers 6



Page 2 of 30


I. Compressor1) The compressor must supply the volume of

air required by all air tools in the plant (totaldraw plus 50 percent).

2) If a compressor is to be purchased, estimatefuture requirements for all air tools in theplant and match the compressor size to theestimate.

3) Rule of thumb: one (each) horsepowerdelivers approximately four cubic feet perminute of air.

J. Pump accumulators—An often overlooked butVERY important aspect of regularly scheduledequipment maintenance is the fluid pumpaccumulator (also called surge chamber).

1) The accumulator is typically on the pressureside of the fluid delivery system and is anintegrated part of the filtering system.

2) The accumulator is a cylinder that isdesigned to act like an air shock to dampenor minimize pressure drop when the pumpchanges direction.

3) If the accumulator is ignored, and notcleaned on a regular basis, material will gelinside it. When this material breaks loose, itwill cause filter and tip plugging, leading topart defects and lost production time.

4) The accumulator may gel to the point whereit no longer is doing its intended job.

5) Accumulators used on most equipment arenot easily cleaned; this is believed tocontribute significantly to problems. NOTE: Ifequipment is cleaned when changing fromone color to another, the accumulator mustalso be thoroughly cleaned. Care should betaken to thoroughly flush the accumulator toremove any residual material that couldcontaminate the next material. Aftercleaning, dry the inside of the accumulatorto remove any cleaning material that may betrapped inside.

6) Some equipment manufacturers havestarted to design and distributeaccumulators that can be easilydisassembled for cleaning. If theaccumulator in use is old and difficult toclean, it may be cost-effective to invest in a

new, more easily cleanable model. Inaddition to time saved, and therefore betterproductivity, a reduction in part defectsshould result.

3. GENERAL CONSIDERATIONS FOR SELECTIONOF SPRAY EQUIPMENT—Before selecting a particularspray gun, determine the following:

A. What type of part is going to be sprayed? Is it asmall, large, flat, curved, simple, or complicatedpart?

B. How many parts are going to be sprayed perday, and will they be sprayed all at once, spaced outevenly during the day, or at several different times?

C. How many different colors are going to besprayed through this gun?

D. What are the future requirements for thisspray gun, and will it be adaptable to otheroperations? Is it a temporary or permanentinstallation?

E. How much physical labor is involved in thisspray application, including the distance the gunmust be moved to spray the part, time required tospray one part, dragging of hoses, setting up, andcleanup?

F. What type of a maintenance program is inplace or can be set up to protect this investment?

G. What are the safety precautions that must beconsidered?

H. Do local air quality regulations require ordisallow a particular type of gun?

After answering the above questions, determine, ingeneral, what type of gun is needed by looking atthe characteristics of spray guns on the market.

4. DESCRIPTION OF TYPES OF SPRAYEQUIPMENT—Spray guns can be classified in anumber of ways:

A. Material delivery—This refers to how thematerial is delivered to the gun. This can be done inthree ways:



Page 3 of 30


DESCRIPTION OF TYPES OF SPRAYEQUIPMENT/ Material delivery continued:

1) Gravity—The material, which is deliveredfrom above the gun, flows to the gun. Thisprocess is not commonly used for gel coats;it is sometimes used for metal flake and veryheavy (viscosity) materials.

2) Siphon—The material is picked up bypassing air over a tube inserted into thematerial (no direct pressure on the material).This process is not commonly used formaking production parts due to slow deliveryrates; it can be used in patching.

3) Pressure—The material is forced to the gunby direct air pressure (pressure vessel) or bya pump. If a pump is used, it has a ratingusually from 2 to 1, up to 33 to 1. The airmotor is from 2 up to 33 times larger thanthe fluid section. This rating means that if apump is rated 4 to 1, for every one psi of airpressure put into the air motor, the fluidsection develops four times that pressure onthe material (in theory). For example:

A 4-to-1 pump at 30 psi is, in theory,delivering material at 120 psi (4 times30). In actual practice, the deliverypressure is lower than theoretical. Theincrease in pressure (4 times) is theresult of the air motor volume being 4times larger than the fluid volume.Pressure feed systems (mainly pumps)are the systems most commonly usedwith gel coats.

B. Method of catalyzation1) ‘Hot Pot’—Catalyst is measured into a

container (pressure pot) and mixed in byhand. This is the most accurate method butrequires more cleanup.

2) Catalyst Injection—Catalyst is added andmixed at (or in) the gun head, requiringseparate lines and a means of meteringcatalyst and material flow.

Figure 4/11.3.1 - Binks Spray Gun

3) Catalyst Slave Pump—A small slave pumpis driven by the master fluid pump. It isengineered to deliver (by volume) ratios of1% to 3% catalyst to the volume of gelcoat/resin that is being delivered. Since thecatalyst slave pump is more foolproof, it isthe most common system used today forboth gel coating and laminating. See Section10. Calibration, I. (the letter) in this chapter.

C. Atomization—With a conventional air-atomizedsystem, the material is ‘broken up’ by direct contactwith an air stream (60 to 90 psi). This can be done inseveral ways:

1) Internal (see Figure 4/II.3.1)—Air and gelcoat meet inside the gun head and come outa single orifice. This system is notrecommended for gel coats except for oneor two special type products as it has atendency to cause porosity and produce arougher film. It also requires a solvent flushsystem.The internal mix nozzle is often employed inhigh production applications of materialswhere fine finish is not required. The internalmix air nozzle can be used only withpressure-feed systems. Only low air andfluid pressures are necessary, and thesemust be regulated so as to be about equal atthe nozzle.



Page 4 of 30


Less air volume is required than withexternal mix nozzles and this, coupled withthe lower air pressure, minimizes amount ofoverspray and rebound. For this reason,internal mix may be referred to assemiairless.Disadvantages of the internal mix air nozzleare few but important: The spray patternsize and shape is controlled by the air cap; arelatively coarse atomization is produced(not suitable for fine finishes); nozzles aresubject to considerable wear (althoughreplacement is easy and low in cost); certaintypes of materials, such as ‘fast driers,’ clogthe exit slot or hole, and film porosity isworse. The gun must be flushed after eachuse.

2) External (see Figure 4/II.3.2)—Air andgel coat meet outside of the gun head ornozzle. This is the most commonsystem. The gel coat is atomized orbroken up in three stages:

DESCRIPTION OF TYPES OF SPRAYEQUIPMENT/ Atomization continued:

a) First stage atomization—As the fluidbeing sprayed leaves the orifice ofthe nozzle, the fluid stream isimmediately surrounded by anenvelope of pressurized air emittedfrom the annular ring around thefluid nozzle tip. The resultingturbulence mixes or coarselyatomizes the fluid with the air.

b) Second stage atomization—Immediately past the first stageatomization, the fluid stream isintersected by jets of air fromconverging holes on each side ofthe annular ring. Two straight holesindexed 90 degrees arecontainment holes which keep thestream from spreading. Theturbulence occurring at theintersecting point of the materialstream and air jets results in a fineratomization.

c) Third stage atomization—The

angular projections on the nozzle(often called ‘wings,’ ‘ears,’ or‘horns’) contain passageways forthe air jets. These jets intersect thestream just after second stageatomization, and at 90 degrees tothe two sets of converging holes.The primary purpose of these jets isto form or shape the round crosssection of the fluid stream into anelongated one referred to as ‘fan’shaped. Additional turbulenceoccurs at this point, resulting inadditional atomization. The spraypattern size is determined by thedesign of the air nozzle, the fancontrol, the method of feeding thespray gun, and the cohesive natureof the material being sprayed.

3) Airless atomization—In an airless system,the gel coat does NOT come in directcontact with compressed air nor is itatomized by air. Instead, a high ratio pump(22:1-33:1) puts the gel coat under highpressure (1000-3000 psi) and forces itthrough a small orifice (0.015 inch to 0.26inch).

As the material passes through theorifice, the material is atomized, similar towater as it exits a garden hose with a spraynozzle. Airless systems are used where highvolumes of gel coat can be handled by theoperator on large, essentially flat or openparts. It is cleaner and more efficient thanconventional air-atomized.

Contrary to what may be assumed,airless atomization does not atomize moremonomer than conventional air spray. Testshave shown that a sprayed film will retainmore monomer (harmful to yellowing andchalk) under these conditions:

a) Airless atomization retains morestyrene than conventional air-atomized.

b) Airless atomization retains morestyrene than ‘properly’ atomized air-assist airless equipment.

c) The closer the gun is to the mold,



Page 5 of 30


the more styrene is going to beretained.

d) The fewer the number of spraypasses, the greater the amount ofstyrene retained. Typically, a ‘fineratomization’ (smallparticles/droplets) will provide a finerorange peel, and therefore bettergel coat film/surface/laminate, whichwill also offer better resistance toyellowing/chalking.

4) Air-Assist Airless—This equipment is acombination of conventional air atomizationand airless techniques.

Figure 4/11.3.2 - Binks Spray Gun

DESCRIPTION OF TYPES OF SPRAYEQUIPMENT/ Atomization continued:

Material is supplied to the airless tip at muchlower pressure (400 to 1000 psi ) than forstandard airless spraying, (1000 to 3000psi). At this low pressure, however, thespray pattern is coarse and has pooratomization. Atomizing air is now introducedto the spray pattern at low pressure, (3 to 30psi), to refine the spray pattern.Excess atomization would return theoperation back to the state of conventionalair atomization.Many of the pumps used are in the 10-to-1to 12-to-1 ratio range, which will do a goodjob on lower viscosity and weight per gallongel coats, but will not do the job whenpumping high viscosity, high weight-per-gallon (white) gel coat, or MACT-compliantgel coats. In many cases, even when pumpsare run at line pressure of 100 psi or more,not enough pressure is developed foradequate breakup.With the low pressure, a very coarse orangepeel pattern is developed due to larger thannormal droplets of gel coat hitting the mold.This causes a wide range of filmthicknesses, as high as 20 mils at the highpoint and 11 mils at the low point. This widevariance causes problems such as:

a) Blister resistance on a 20/11 orangepeel-type situation would only be asgood as the 11 mils area, but withmuch more material actually used.

b) Quick sand through in thin areas oforange peel.

c) Roll out of skin coat over coarseorange peel is often more difficultand will contribute to a defectcustomers call shotgunning orbuckshot: small air bubbles trappedin the low areas of coarse orangepeel. These small air bubbles showup on the finish after buffing or afterthe parts are heated in the sun. A22-to-1 or higher pump ratio isrecommended to achieve a goodbreakup with pump pressures in the



Page 6 of 30


30-to-75 psi range. This reduceswear and tear on seals, minimizesthe effect of plant air fluctuations,and allows for adjustments due towear on the tip.

5) High Volume Low Pressure (HVLP)—Thistype of equipment is not new to the paintindustry but is relatively recent to the gelcoat industry. California customersespecially are using it in an attempt to cutdown on emissions (use of the gun isintended to cut down on emissions, ormonomer loss). This method of sprayingresults in larger droplets, a film with verycoarse orange peel (causing rollout to bemore difficult), and a wetter, more styrene-rich film that is more prone to sag.A typical HVLP gun is manufactured so thatno more than 10 psi of atomizing air is at thegun for atomization. Gel coat is atomized bythe higher volume (cfm) of air. Results

(application and monomer retention) similarto the HVLP have been obtained by merelyturning atomizing air way down with theconventional air-atomized gun (see Test 5on the chart on this page).Note also that airless and air-assist airlessretain more styrene in the film thanconventional air-atomized equipment.

6) Non-atomized Spraying, Fluid Impingementor Convergence—With this method, new tothe polyesters industry, gel coat is sentthrough two orifices in the head whichconverge or impinge on each other. Whenthis happens, a fan occurs. This isaccomplished at lower pressures than withthe other systems. Larger tips are used withless overspray. Note that the fan pattern willhave a different appearance than withcurrent systems (large droplets and slightlymore orange peel.)



Page 7 of 30


PERCENT MONOMER IN GEL COAT FILM

Control (material not

sprayed)

Conventional Air

Spray

Airless Air-Assist

Airless

HVLP**

Test 1

38.3% 32.9%

(Tip 2140)

34.4% — —

Test 2

35.8%

34.6%

36.4%

—

—

—

(Tip 1750)

20.7%

—

22.6%

(Tip 2640)

27.4%

28.0%

28.6%

(Tip 2640)

24.9%

23.1%

24.7%

—

—

—

—

Test 3

41.8%

2 to 3 ft.*

6 ft.*

—

—

—

(Tip 2140)

34.7%

30.8%

—

—

—

—

—

—

Test 4

47.0%

1.5 ft.*

3.0 ft.*

4.5 ft.*

6.0 ft.*

—

41.4%

32.5%

—

—

(Tip .021 inch)

43.8%

41.7%

40.0%

37.4%

—

—

—

—

—

—

—

—

—

—

Test 5

34.3% (60 psi)

26.6

(20 psi)

28.9

— — 29.0



Page 8 of 30


ITEM Hot Pot

A

Hot Pot

B

Hot Pot

C

Air-Atomized

Catalyst

Injection

Airless

Catalyst

Injection

Air-Assist

Airless

FIT or Convergence

Material

supply

1 quart 1 or 2

gallon

1 to 20 gal. pressure

pot or pump

Pump Pump

Part size Small up to

20 sq. ft.

Small to

medium up

to 40 sq ft.

Medium to

large

150 sq. ft.

Various Various Various Various

Number of

parts

One or two One or two One or two Any number Any number Any number Any number

Us Intermittent Intermittent Intermittent Constant Constant Constant Constant

Switching

colors

Easy Easy Fair (hose

must be

cleaned)

Fair (separate

pressure pots

normally used)

Pump and lines

must be cleaned

Pump and lines

must be cleaned

Pump and lines must be cleaned

Future use Very

flexible,

tooling

prototype

small runs

Tooling,

small jobs

Tooling,

small jobs

Large production Large production Medium to

large production

Large production

Portability Easy to

move

Easy to

move

Easy to

move

Fixed or cart

mounted

Fixed or cart

mounted

Fixed or cart

mounted

Fixed or cart mounted

Number of

hoses

One Two Two 2 to 4 hoses may be

on a boom

2 to 4 hoses may

be on a boom

2 to 4 hoses may

be on a boom

2 to 4 hoses may be on a boom

Catalyst

Measurement

Weight or

volume

Weight or

volume

Weight or

volume

Metered (requires

calibration)

Metered (requires

calibration)

Metered (requires

calibration)

Metered (requires calibration)

Mixed by Hand Hand Hand By gun By gun By gun By gun

Cleaning After each

use

After each

use

After each

use

Wipe gun off

intermittently. Clean

pots or pump

Wipe off tips

intermittently.

Clean pots or

pump

Wipe off tips

intermittently.

Clean pots or

pump

Wipe off tips intermittently. Clean

pots or pump



Page 9 of 30


5. SPRAYING MACT-COMPLIANT GEL COATSWITH AIR-ASSIST AIRLESS AND NON-ATOMIZEDEQUIPMENT—With the emphasis on reducing theemissions of Hazardous Air Pollutants (HAP), MaximumAchievable Control Technology (MACT) Compliant (MC)gel coats have been introduced to the industry. MC gelcoats—because they have less monomer—will pump,spray, and flow differently than standard gel coats. Also,new spray equipment with Non-atomized ApplicationTechnology (NAT) uses a different principle thanconventional equipment to break up gel coat.

Because MC gel coats are high solids gel coats, they donot flow through hoses or pipes as easily as non-MC gelcoats, and there is a greater pressure drop at the end ofsmall hoses or pipes while spraying.

Since lower spraying pressures are needed and thereare fewer monomers in MC gel coats, materialtemperature and fluid line size become more critical.

A. Temperatures—NOTE: The viscosity of MC gelcoat increases more than that of standard gel coatsas the temperature drops due to less monomer. Forgood spray characteristics, the temperature of theMC gel coat should be 75ºF (25ºC) or higher. Fewerproblems will be encountered if the work area istemperature-controlled (preferably 80ºF (27ºC)),rather than relying on the use of band heaters or in-line heaters.

Use of band or drum heaters is not recommendedbecause gel coat is an insulator and can beoverheated very easily, which will cause prematuregellation. Also, malfunctioning thermostats orheaters left on overnight can cause the whole drumto gel.

Use of an in-line heater will allow use of smaller tipsas well as lower flow rates.

While in-line heaters present fewer problems thanband or drum heaters, gellation can occur. If an in-line heater is used, make sure it can bedisassembled and bored out if gellation occurs.

Also, when using in-line heaters, the lines should beinsulated. A bypass valve near the gun can be usedto draw off material until heated gel coat reaches thegun. This valve should be a locking type, so itcannot be accidentally bumped on. The materialcoming out of the gun should be 90 to 95ºF (32 to

35ºC). Do not heat gel coat over 100ºF (38ºC)because stability is greatly decreased as thetemperature rises.

B. Fluid line size—For standard (non-MACT-compliant) gel coats, a 3/8-inch hose with a 3- or 4-foot, 1/4-inch whip works well, but a 1/2-inchdiameter hose with a 3/8-inch whip works betterbecause lower pump pressure can be used.

For MC gel coats, a 1/2-inch hose with a 3-foot, 3/8-inch whip is recommended for up to 30 feet.

For up to 75 feet, use a 3/4-inch hose for the first 50feet, and then drop down to a 1/2-inch hose with a 3-foot, 3/8-inch whip. Runs of more than 75 feetshould be hard-piped with large lines, 1-inch orlarger. For recommendations, contact yourequipment supplier.

C. Spraying the film—Film build is quicker with anMC gel coat due to less overspray. Film build speedincreases even more when non-atomized applicationtechnology (NAT) equipment is used because thespray is softer (less atomization). Also, it is importantto keep in mind that multi-pass spraying of MC gelcoats can be counter-productive; the more passesthat are used to apply a given thickness of film, themore emissions will go into the air. The fewer thespray passes, the fewer emissions released.

Film should be sprayed in at least two passes. Thefirst pass should be the thinnest continuous wet filmpossible, somewhere around 8 to 10 mils. Thesecond pass can be another 8 to 10 mils, for a totalfilm thickness of 16 to 20 mils. If the second pass isthinner than 8 mils, then a third pass can finish from16 to 20 mils. If spraying below the water line,another 4 mils can be added for a total of 20 to 24mils for better water blister resistance.

NOTE: Do not spray a dry film. Each pass must bedeveloped through a wet film and perpendicular tothe previous film. Gel coats should not be sprayedmore than 4 feet from the mold because they can godry.

Use of a constantly recirculating system is notrecommended because it can cause viscosity todrop or can introduce large amounts of air into thegel coat.



Page 10 of 30

6. SPRAYING WITH NON-ATOMIZED APPLICATIONTECHNOLOGY (NAT) EQUIPMENT—FluidImpingement Technology equipment uses two streamsof gel coat which hit (collide) with each other to form thegel coat fan pattern. This is done under low pressure(11:1 pump) and produces larger droplets than an air-assist airless or airless setup. The lower pressure andlarger droplet size account for the lower emissions andreduced over-spray. These factors will alter theappearance of the spray pattern.

Gun pressure settings will need to be adjusted,sometimes to settings that will be the opposite of thoseused with air-assist airless or airless systems.

The impingement tip will have two holes angled so thatthe fluid streams will meet (impinge) each other within aninch of the tip. Usually the first two numerals of the tipnumber will indicate the size of each hole (inthousandths of an inch). The third and fourth numeralsdoubled will indicate the approximate fan angle. Thelarger these last two numbers, the wider the fan patternwill be.

Tips are available in orifice sizes of 15, 17, 20, 22, 25,27 and 30 (tip size below 17 is not recommended asplugging can occur). Fan angle sizes are 17, 20, 22, 25,27 and 30. Starting tips for standard gel coats (non-MC)are 1720 or 2520, with a 40 to 60 psi pump pressure.

While larger tips are used with whites and colors, smallertips may be appropriate for both colors and clears.

The chart below gives examples of pressure drops for anMC white gel coat.

TIP PRESSURE

at PUMP

(PSI)

FEET of ¾-

INCH HOSE

or PIPE

FEET of

½-INCH

HOSE

PRESSUR

E DROP at

GUN

252

0

700 20 0 0

252

0

600 20 20 0

252

0

650 0 40 -400

232

0

500 70 0 -150

232 700 70 0 -100

As a startup procedure, start the pump at zero, thenincrease the pressure in five-psi increments until the fan

droplets are all about the same size. This uniformity willappear immediately following the disappearance of the‘fingers.’ NOTE: The droplets will be larger in size thanwhen using air-assist airless or airless equipment.

With impingement technology, spray will be more coarsewith a rougher pattern but will have fewer tendencies forporosity.

Do not adjust to achieve a finer particle size becauseporosity can occur, emissions may increase, and fanedges may be ragged. To clean up edges, use a smallamount of refinement air.

Some adjustments will be opposite those normally usedwith air-assist airless and airless equipment. Forexample, with impingement technology, better breakupcan be achieved by using a larger tip at a lowerpressure. (Air-assist is not used for breakup, it is turnedon only slightly to clean up fan edges. If turned too high,emissions go up and porosity occurs.) If breakup is notachieved, or if pump pressure is running above 80 psi,try a larger tip and/or a larger hose (the opposite of theaction to take with air-assist airless). Catalyst air shouldbe 10 to 15 psi.

In cases where flow rates are slightly higher and morematerial is going into the mold, only two passes will beneeded to achieve proper film build. NOTE: Do not dustcoat. Use a thin continuous film for the initial coat.

Because the fluid velocity is lower, the maximum spraydistance from the mold is 3 feet. Tight areas may bemore challenging to spray.

The chart below shows flow rates using impingementequipment with 25% HAP white gel coat:

TIP NO HEAT—

Lbs./Minute

HEATER—

Lbs./Minute

BREAKUP

1925 2 to 3 2 to 3 Fair

2120 2.5 to 3 2 to 3 Good/Fair

2520 4 to 5.5 Good

SPRAYING WITH NON-ATOMIZED APPLICATIONTECHNOLOGY (NAT) EQUIPMENT continued:

NOTE: With the heater off, pump pressure must be



Page 11 of 30


increased for good breakup; therefore, the flow rate ishigher.

For smaller, more intricate parts, use a smaller tip. Uselarger tips for large, wide open, easy-to-spray parts.

Because impingement equipment operates at lowerpressure, there may be a very slight ‘wink’ in the fanpattern; however, it should not be pronounced. If that isthe case, use a larger surge chamber, or warm thematerial (if it is cold).

Due to the larger droplets, the pattern will be rougherlooking; the final film backside may also appear slightlyrougher than it would with an airless or air-assist gun.However, adjusting to a finer droplet may create porosityand increased emissions.

It is important to USE A MIL GAUGE.

Adjusting pump pressure (1/2 inch hose with a 3/8 inchwhip) for proper breakup, using various tips and withoutheat, yielded the results shown in the chart below:

HEATE

R

TIP PRESSUR

E (PSI)

BREAK-

UP

FLOW RATE

Lbs./Minute

OFF 2120 90 POOR NA

OFF 2520 75 OK 5.7

ON* 2520 40 OK 3.4

ON* 2120 45 OK 2.1

ON* 1925** 50 OK 1.8

7. SPRAYING MC GEL COATS THROUGHSTANDARD AIR-ASSIST AIRLESS OR AIRLESSEQUIPMENT—Because MC gel coats contain lessmonomer, emissions are reduced. However, this alsoalters how the gel coats flow and break up.

MC gel coats are harder to spray than standard gelcoats through air-assist airless and standard airlessequipment, but this can be achieved.

Because MC gel coats flow differently, CCPrecommends a 22:1 pump to ensure that air pressurescan be kept in the 40 to 75 psi range for better controland less wear on the pump. Pump pressure should beadjusted with the air assist turned on just enough toproduce proper breakup. Always use minimum pumpand air assist pressure.

Spray the gel coat on in a continuous film thickness of 8to 10 mils per pass. Rely on a mil gauge, as thebackside will have a different appearance than non-MCgel coats.

Use a 0.018-inch tip for clears and small parts; the flowrate will be about 2½ pounds per minute. For decks orcomplex parts, use a 0.21-inch or 0.023-inch tip; flowrate will be from 2½ to 3½ pounds per minute. With 0.26-inch tip, used on large flat or open parts (hulls), flow ratewill be about 4 pounds per minute.

8. SPRAY SYSTEM SELECTION—There are anumber of spray guns that can be used for polyester.See the charts on the following pages for basiccharacteristics of these tools.

9. SPRAY SELECTIONS AND SETTINGS—Once aspray system has been selected, the next step is todetermine the recommended starting pressure settingsand spray procedures. These settings may have to bechanged slightly to match a part and spray operator.Also check with the equipment manufacturer for setupprocedures and handling precautions.

10. CALIBRATION—Since polyesters require theproper amount of catalyst to be added and mixed in toachieve desired properties, it is necessary to calibratecatalyst injection spray equipment.

Because wear on equipment and temperature, and thedifferences of flows between materials will change thecatalyst ratio, it is not possible to rely on setting pressurereadings once and then using them continuously dayafter day.

CALIBRATION continued:

Different colors produce different flow rates (at equal



Page 12 of 30

pressures) and present another reason to be concernedwith calibration. Calibration should be done weekly or foreach batch change. Setting up a calibration routine—such as the first thing every Monday morning—is aneasy and worthwhile habit to establish.

Consult the equipment manufacturer and the literaturefor recommended calibration methods and procedures.

A. Safety considerations

1) Always wear eye protection.2) Never point the spray gun at self or others3) Always ground spray equipment.4) Before working on equipment, depressurize

by turning the air supply off and then pullingthe trigger of the spray gun and bleeding thebypass at the filter.

5) Never trust spray equipment even if all thegauges say zero pressure. If there is anydoubt that the equipment is still pressurized,and it must be dismantled to relieve thepressure, keep protection between theoperator and the equipment (such as apiece of cardboard or rag), and always weareye protection.

6) Airless (high pressure) systems can createenough pressure to force the materialthrough human skin—BEWARE!

7) Read all Material Safety Data Sheets andEquipment Safety Sheets.

8) Always turn valves on slowly to avoidsudden surges of pressure that can rupturehoses.

B. General procedures for determining flow ratesand percent catalyst of gel coat include:

1) With X grams of material collected in 30

seconds and a desired flow rate expressedin pounds per minute:X grams times 2 = Grams Per Minute

(GPM).GPM = Pounds Per Minute (PPM)454(1 lb. = 454 grams)Example: 300 grams in 30 seconds300 x 2 = 600 GPMGPM = 1.32 PPM454

2) With X pounds of material collected in 30seconds and a desired flow rate expressedin GPM:

X pounds times 2 = Pounds Per Minute(PPM)PPM x 454 = GPMExample:0.66 pounds in 30 seconds0.66 x 2 = 1.32 PPM1.32 x 454 = 600 GPM

3) To determine the amount of catalyst neededfor a flow rate, multiply the grams per minuteof gel coat by percent catalyst desired.Example:Flow rate is 600 GPMPercent catalyst desired is 1.8%600 x 1.8% = 10.8 grams or cc’sPercent catalyst desired is 1.8%600 x 1.8% = 10.8 grams or cc’s

NOTE: This test can also be run for a 15-secondcollection time; then, to calculate the grams perminute, multiply by 4 instead of 2.



Page 13 of 30


HOT POTDeVilbiss JGA-502 Binks 2001

Items Needed 1 Quart 2 Quarts to 20 Gallons 1 Quart 2 Quarts to 20 GallonsContainer Attached Remote Attached RemoteCatalyst Hand mixed Hand mixed Hand mixed Hand mixedAir atomization External External External ExternalCFM 17 @ 70 psi 17 @ 70 psi 17 @ 70 psi 17 @ 70 psi

Air cap AV-1239-704 AV-1239-704 67 PB 67 PBFluid nozzle AV-601-E AV-601-E 67 67Needle JGA-402-E JGA-402-E 67 67PressureAir*Fluid

60 - 9010 - 25

60 - 9015 - 45

60 - 9010 - 25

60 - 9015 - 45

Delivery (lbs./minute) 1 to 2.5 1 to 2.5 1 to 2.5 1 to 2.5Spray distance 18 to 24 inches 18 to 24 inches 18 to 24 inches 18 to 24 inchesNumber of passes 3 3 3 3Mils per pass 5 to 7 5 to 7 5 to 7 5 to 7



Page 14 of 30

CONVENTIONAL AIR-ATOMIZED CATALYST INJECTION

Spray Gun

Binks 18N

Catalyst Injection

Binks 18C

Catalyst Side Injection

Glas-Craft ISD

C-20 Gel Coat

Nozzle Kit

Air cap A63 PB 63 PB Stage 2

Fluid orifice 66SS 66 .078 orifice

Needle 65 65 External

Atomization External External 60 to 90 psi

Air atomization* 60 to 90 psi (carries

catalyst)

0 to 90 psi —

Catalyst Std MEKP As required As required

Catalyst pressure — As required As required

Ball setting (top) As required As required As required

Material supplyPump pressure (4:1)Pot pressure

25 to 3520 to 45

25 to 3520 to 45

25 to 3520 to 45

CFM 17 @ 90 psi 17 @ 90 psi 17 @ 90 psi

Delivery (lbs./minute) 1 to 2.5 1 to 2.5 1 to 2.5

Spraying distance 18 to 24 inches 18 to 24 inches 18 to 24 inches

Number of passes 3 3 3

Mils per pass 5 to 7 5 to 7 5 to 7

Calibration (material &

catalyst)

Gel times Flow and gel times Gel times



Page 15 of 30


AIRLESS CATALYST INJECTION A

Binks Mavrick

TYPE Binks 43 PL

with ACI with 3400

STAR

Catalyst *Diluted MEKP MEKP Standard MEKP Standard MEKP Standard

Catalyst atomization

and mix

Airless

Pressure

External

Air

External

Air

External

Air

External

Catalyst tip 0.011 to 0.013 0.052 0.015 Fixed

Catalyst injector

pressure

25 to 60 psi 25 to 35 psi As required As required

Catalyst atomizing

pressure

— 3 to 5 lbs. lower At least 60 15

Gel coat pump 33:1 33:1 33:1 24:1

Pump pressure 50 to 90 50 to 90 50 to 90 50 to 90

Material tip 0.015 to 0.026 0.015 to 0.026 0.015 to 0.026 0.015 to 0.026

CFM 40 CFM max. 40 CFM max. 40 CFM max. —

Delivery

(lbs./minute)

2 to 4 lbs. 2 to 4 lbs. 2 to 4 lbs. 2 to 4 lbs.

Passes 3 3 3 3

Mils per pass 5 to 7 5 to 7 5 to 7 5 to 7

Spraying distance 24 to 36 inches 24 to 36 inches 24 to 36 inches 24 to 36 inches

Calibration Flow rate and gel

time

Flow rate and gel time Flow rate and gel time Flow rate and gel time

Fan pattern Vertical Horizontal or vertical Horizontal or vertical Vertical

* See catalyst and equipment manufacturers for proper diluents and instructions.



Page 16 of 30

AIRLESS CATALYST INJECTION B

TYPE Glas-Craft LPA Venus Internal Mix GS Manufacturing Polycraft G555

Catalyst MEKP Standard MEKP Standard MEKP Standard MEKP Standard

Catalyst

atomization and

mix

Air

External

—

Internal

Airless

External

Air

External

Catalyst tip External — .011 to .013 Fixed

Catalyst injector

pressure

35 to 50 psi Same as material 100 (catalyst

regulated by fluid

regulator)

30 to 40

Catalyst atomizing

pressure

At least 2 psi below

catalyst pressure

— — 3 to 5 lbs. lower

Gel coat pump 33:1 11:1 20:1 30:1

Pump pressure 50 to 90 60 to 90 50 to 90 50 to 90

Material tip 0.015 to 0.026 0.015 to 0.026 0.015 to 0.026 0.015 to 0.026

CFM — — — —

Delivery

(lbs./minute)

2 to 4 lbs. 2 to 4 lbs. 2 to 4 lbs. 2 to 4 lbs.

Passes 3 3 3 3

Mils per pass 5 to 7 5 to 7 5 to 7 5 to 7

Spraying distance 24 to 36 inches 24 to 36 inches 24 to 36 inches 24 to 36 inches

Calibration Flow rate and gel time Flow rate and gel time Flow rate and gel

time

Flow rate and gel time

Fan pattern Horizontal or vertical Horizontal or vertical Horizontal or vertical Horizontal



Page 17 of 30


AIR-ASSIST AIRLESS CATALYST INJECTION

TYPE

Binks 118-AC/

Vantage 11C

Magnum

ATG 350

Polycraft

G-755

GS Mfg Glas-Craft

LPA II

Binks

102-2400

Catalyst MEKP

Standard

MEKP

Standard

MEKP

Standard

MEKP

Standard

MEKP

Standard

MEKP Standard


and mix

—

External

Air

External

Air

External

Air

External

Air

External

—

External

Catalyst tip .013 Fixed Fixed Fixed Fixed .013

Catalyst injector

pressure (psi)

10 to 15 (Plug

groove valve

at the gun)

60 25 to 45 As required As required 10 to 15

Gel coat pressure

(psi)

clears

colors

400 to 600

600 to 1000

400 to 600

600 to 1000

400 to 600

600 to 1000

400 to 600

600 to 1000

400 to 600

600 to 1000

400 to 600

600 to 1000

Pump pressure (psi) Dependent

upon size of

pump

Dependent

upon size of

pump

Dependent

upon size of

pump

Dependent

upon size of

pump

Dependent

upon size of

pump

Dependent upon size of

pump

Material tip .018 to .026 .018 to .026 .018 to .026 .018 to .026 .018 to .026 .018 to .026

Air-assist air* 5 to 30 5 to 30 5 to 30 Fixed 5 to 45 5 to 30

CFM — — — — — —

Delivery (lbs./minute) 2 to 3 lbs. 2 to 3 lbs. 2 to 3 lbs. 2 to 3 lbs. 2 to 3 lbs. 2 to 3 lbs.

Passes 3 3 3 3 3 3

Mils per pass 5 to 7 5 to 7 5 to 7 5 to 7 5 to 7 5 to 7

Spraying distance 24 to 36

inches

24 to 36

inches

24 to 36

inches

24 to 36

inches

24 to 36

inches

24 to 36 inches

Calibration Flow rate and

gel time

Flow rate and

gel time

Flow rate and

gel time

Flow rate and

gel time

Flow rate and

gel time

Flow rate and

gel time

Fan pattern Vertical Vertical Vertical Vertical Vertical Vertical

* As low as possible.



Page 18 of 30

C. Binks—18-N1) Select and install correct air cap, nozzle,

and needle in gun.2) Attach fluid hose to gun.3) Check pump filter and lines.4) Put pump in gel coat container.5) Back out regulator and make sure pressure

is off. To pump, turn on air to pressuregauge. Then slowly increase pressure untilpump starts.

6) Adjust pressure to 30 psi on pump (4-to-1)and check for leaks.

7) Run flow rate 30 seconds (catch in apreviously weighed container); adjust to 1 to2.5 pounds per minute. NOTE: Gel coatsmust be weighed, as volume measurementswill not be accurate due to densitydifferences.

8) Check catalyst level in tank (#5200) and fill ifnecessary.

9) Attach and check catalyst lines.10) Back out regulator to make sure it is off.

Turn on air to catalyst pressure gauge. Thenslowly turn to 30 psi. STOP. Check for leaks.Then adjust injector pressure to 70 to 90 psi.A T-gauge must be used (Binks Part #73-125) to check pressure at the gun. If flowrate is at maximum 2½ pounds, 60 psi isrequired (with fan full open) to properlyatomize the gel coat. NOTE: 100 psimaximum on Binks injector; 80 psi maximumon Glas-Craft I injector.

11) Check atomization and adjust as necessary(either air or fluid). NOTE: If adjustingdownward, relieve pressure in lines as thecheck valve may retain the original pressureuntil relieved by pulling the trigger.

12) Calculate amount of catalyst necessary forthe flow rate.

13) CAUTION: Do not rely on catalyst charts.Confirm the flow rate manually.

14) Adjust the ball to this reading. Turn top knoball the way open, then 1½ turns in; adjustball with bottom knob to the right side.

15) Spray the catalyzed material onto a glasspanel and collect by scraping about 100grams into a paper cup. Note the gel time.

16) For gel time comparisons, take gel coat fromthe container and weigh out 100 grams. Add

the same amount of catalyst as calculated inC.12 and run the gel time.

17) Compare gel times and adjust catalystinjector if necessary. The catalyst ball canbe adjusted in five-unit steps until desiredgel time is reached, but stay in the 1.2-to-3percent range.

18) Wipe off gun after each use.

D. Binks—18-C

1) Select and install correct air cap, nozzle andneedle in gun.

2) Attach fluid hose to gun.3) Check pump filter and lines.4) Put pump in gel coat container.5) Back out regulator and make sure pressure

is off. Turn air on to pressure gauge atpump. Then slowly increase pressure untilpump starts.

6) Adjust pressure to 30 psi on pump (4 to 1)and check for leaks.

7) Run flow rate 30 seconds; adjust to 2 to 2½pounds per minute. Catch in a previouslyweighed container. NOTE: Gel coats mustbe weighed, as volume measurements willnot be accurate due to density differences.

8) Release pressure on pump, and bleed atgun and bypass valve.

9) Calculate amount of catalyst necessary forthe gel coat flow rate.

10) CAUTION: Do not rely on catalyst charts.Confirm the flow rate manually.

11) Check catalyst level in tank (#5202) and fill ifnecessary.

12) Attach and check catalyst lines.13) Back out regulator to make sure it is off.

Turn air on to catalyst pressure gauge.14) Adjust the ball for appropriate reading.15) Collect catalyst for one minute and figure

percent.16) Adjust catalyst ball if required and run

catalyst flow rate again.17) Turn on gel coat pump to previous pressure

setting and run gel time comparison (seeC.15, C.16, C.17).



Page 19 of 30



Page 20 of 30


AIR-ASSIST AIRLESS SLAVE ARM CATALYST NON-ATOMIZED

TYPE MAGNUM ATG

3500

Venus Pro Gel

Coat

Glass Craft

AAC

Binks 102-

2400

FIT MAGNUM POLYCRAFT

Catalyst MEKP Standard MEKP

Standard

MEKP

Standard

MEKP

Standard

MEKP

Standard

MEKP Standard


and mix

5 to 30

External

Internal Mix* 35+

External

—

External

5 to 30

External

5 to 30

Catalyst tip Fixed Internal Fixed 0.013 Fixed Fixed

Catalyst slave arm Set as desired Set as desired Set as desired Set as desired Set as desired Set as desired

Gel coat pressure

Clears

Colors

400 to 600

600 to 1000

400 to 600

600 to 1000

400 to 600

600 to 1000

400 to 600

600 to 1000

300 to 600 300 to 600

Pump pressure Dependent

upon size of

pump

Dependent

upon size of

pump

Dependent

upon size of

pump

Dependent

upon size of

pump

30 to 60 30 to 60

Material tip 0.018 to 0.026 0.018 to 0.026 0.018 to 0.026 0.018 to 0.026 Contact

manufacturer

Contact manufacturer

AAA (psi) 5 to 30 5 to 30 10 to 15 5 to 30 Low Low

CFM — — — — — —

Delivery

(lbs./minute)

2 to 3 lbs. 2 to 3 lbs. 2 to 3 lbs. 2 to 3 lbs. 2 to 3 lbs. 2 to 3 lbs.

Passes 3 3 3 3 3 3

Mils per pass 5 to 7 5 to 7 5 to 7 5 to 7 5 to 7 5 to 7

Spraying distance 24 to 36 inches 24 to 36 inches 24 to 36 inches 24 to 36 inches 24 to 36 inches 24 to 36 inches

Calibration Flow rate and

gel time

Flow rate and

gel time

Flow rate and

gel time

Flow rate and

gel time

Flow rate and

gel time

Flow rate and gel time

Fan pattern Vertical Vertical Vertical Vertical Vertical Vertical

* Solvent flush requires 30 to 40 psi.



Page 21 of 30


E. Airless with airless atomized catalyst system(Binks 43 PL and GS)

1) Select fluid material tip and put on gun.2) Check fluid lines and pump filter.3) Put pump in gel coat. (If catalyst slave

pump, disconnect. See Section 10.Calibration, I. (the letter) in this chapter.)

4) Back out regulator and make sure pressureis off. Turn air on to pump gauge. Thenslowly turn pressure up until it starts. Checkfor leaks.

5) Turn pressure up to approximately 60 psiand slowly adjust pressure until tails areeliminated at 24 inches from the gun head.

6) Take flow rate in pounds per minute, 2 to 4.Use no more than 3 pounds forsmall/intricate molds, no more than 4pounds for large/open molds.

7) Release pressure off pump, bleed at gunand bypass valve.

8) Wipe off gun.9) Check catalyst level in tank. Fill if necessary

(If catalyst slave pump, reconnect.) NOTE:May require special viscosity MEKP. Consultcatalyst manufacturer.

10) Check fitting and lines and install catalysttip. Start with .011.

11) Back off regulator and make sure it is off.Turn on air to catalyst gauge. Slowly adjustpressure to catalyst supply. Stop at 15 psi.Check for leaks.

12) Adjust catalyst pressure for properatomization.

13) Run flow on catalyst in graduated cylinder.Calculate percent catalyst and adjust ifnecessary. Check gel time, adjust asdesired but remain in the 1.2 to 3 percentcatalyst range. If diluted catalyst is used, thepercent of diluent must be taken intoconsideration.

14) Turn on gel coat pump to previous settingand run gel time comparison (see C.15,C.16, C.17).

F. Airless with internal air-atomized catalystand external mix (Binks Maverick ACI, Glas-Craft,Polycraft, Star, Magnum).

1) Select correct tips and put on gun.

2) Check pump filter and material lines.3) Put pump in gel coat. ( If pump is a catalyst

slave pump, disconnect. See I. in thissection).

4) Back out regulator and make sure pressureis off. Turn air on to pump gauge; thenslowly increase pressure on pump until itstarts. Check for leaks.

5) Turn pressure up to approximately 60 psiand slowly adjust until tails are eliminated at24 inches from the gun head.

6) Take flow rate, 2 to 4 pounds per minute.Use no more than 3 pounds forsmall/intricate molds, and no more than 4pounds for large/open molds.


8) Wipe off gun.9) Check catalyst level in tank. Fill if necessary.10) Check catalyst and air line. (Reconnect

catalyst slave pump if used).11) Back off regulators.12) Adjust catalyst atomizing air and catalyst

pressure, and check for leaks.13) Calculate amount of catalyst necessary for

the gel coat flow rate.14) Check catalyst atomization and adjust ball

for the required amount of catalyst.15) Run catalyst flow. Compare to gel coat flow.

Adjust if necessary. If catalyst pressure is tobe decreased, the catalyzer pot pressure will

need to be bled before calibrating.16) Turn on gel coat pump to previous setting

and run gel time comparisons (see C.15,C.16, C.17).

G. Airless with external air-atomized catalystsystem and external mix (Binks Maverick-3400).

1) Select correct tips and put on gun.2) Check pump filter and material lines.3) Put pump in gel coat.4) Back out regulator and make sure pressure

is off. Turn air on to pump gauge; thenslowly increase pressure on pump until itstarts. Check for leaks.

5) Turn pressure up to approximately 60 psiand slowly adjust until tails are eliminated at24 inches from the gun head.



Page 22 of 30

Airless with external air-atomized catalystcontinued:

6) Take flow rate, 2 to 4 pounds per minute.Use no more than 3 pounds for small/intricate molds,no more than 4 pounds for large/open molds.


8) Wipe off gun.9) Check catalyst level, fill if necessary.10) Calculate amount of catalyst necessary for

the gel coat flow rate.11) Turn on catalyst pot or pump slowly. Check

for leaks.12) Run catalyst flow rate and adjust pressure

up and down to achieve catalyst desired.13) Adjust catalyst pressure as required for fine

atomization of catalyst—no catalyst droplets.14) Turn on gel coat pump to previous setting

and run gel time comparisons (see C.15, C.16,C.17).

H. Air-assist airless (Binks 118-AC/Vantage II-C,Polycraft G755, Magnum ATG3500, GSManufacturing, Glas-Craft LPA, Binks 102-2400).

1) Select correct tips and put on gun.2) Check pump filter and material lines.3) Put pump in gel coat. If catalyst slave pump

disconnect. See Section 10, Calibration, I. (theletter) in this chapter.

4) Back out regulator and make sure pressureis off. Turn air on to pump gauge; then slowlyincrease pressure on pump until it starts. Check forleaks.

5) Turn pressure up to approximately 30 to 50psi (largely dependent upon pump ratio). Do notexceed 600 psi gel coat pressure with clear gel coat,nor more than 1,000 psi with color gel coat. Thepressure will vary according to tip size, gel coatviscosity and temperature. Ideally, gel coat pressureshould be as low as possible while still maintaining agood fan and flow rate. Do not be concerned withfingers or tails because the air-assist will refinethem.

6) Take flow rate; do not exceed 3 pounds perminute.


8) Check catalyst level, fill if necessary (ifcatalyst slave pump, reconnect).

9) Run catalyst flow:

If 118AC, Vantage II-C or 102-2400 as inD.9 through D.17.If G-755, ATG-3500, GS or Glas-craft LPAII, as in F.12 through F.16.

10) Adjust air-assist air. Use only as littlepressure as possible so as to minimize thefingers and tails.

I. Do not assume that a catalyst slave pump isdelivering the correct amount of catalyst.

The catalyst delivery can be off due to inaccurateslave pumps, wear, leaks, clogged filters oratomizing pressure that is too high.

If the slave pump is suspected to be inaccurate,calibrate the pump according to the manufacturer’srecommendations. Equipment manufacturers offercalibration kits for checking slave pump calibration.

In addition, slave settings are based on volumepercentages. CCP’s catalyst specifications arebased on weight percentages. There is an inherenterror introduced due to the variation of the weightper gallon of the gel coat:

Weight/Gallon

of Gel Coat

Slave Pump

Setting

Actual

Weight %

8.8 (Clears) 1.8 1.9

9.8 (Colors) 1.8 1.7

10.8

(Whites)

1.8 1.5

11.8 (Low

VOC)

1.8 1.4

An alternative, but not quite as accurate, procedureto a calibration kit is to use the stroke-countingmethod. The stroke-counting method is to count thepump strokes while checking the flow rate. After theflow rate is determined, disconnect the gel coatsupply to the gun. Open the bypass valve on thepump and adjust the valve so the pump is strokingthe same number of strokes per minute as when theflow rate was checked. Collect catalyst out of the tipof the gun while allowing the pump to pump gel coat

Airless with external air-atomized catalystcontinued:through the bypass at the determined stroke-per-



Page 23 of 30


minute rate. Divide the catalyst flow rate by the gelcoat flow rate to get percent of catalyst. Catalystpercent should be approximately ± 0.10 percent ofthe slave pump setting. Confirm by running gel timecomparisons (see C.15, C.16, C.17).

In addition, the pump must be checked and primedeach day because gas pockets can form, causingcavitation.

Monitor the filter to ensure it is not plugged orrestricted.

11. CLEANUP PROCEDURES

A. Relieve all pressure from pump and lines.

B. Place pump in container of wash solvent.

C. Wipe down outside of pump.

D. Remove and clean spray tips.

E. Turn up pressure slowly until pump just startswith trigger pulled.

F. Run 2 to 3 gallons of solvent through pump andlines, then relieve all pressure. Spray into bucketfor disposal. Do not let the pump cycle (bothstrokes) more than one per second.

G. Carefully open bypass at filter.

H. Remove and clean filter; replace if necessary.Every two weeks check and/or clean surgechamber.

I. Put pump in container of clean solvent.

J. Repeat steps F through G.

K. Wipe hoses and gun down.

L. Grease or lubricate necessary parts.

M. Inspect for worn parts and order replacements.

N. Make sure pump is stopped in down position toprolong packing life (make sure lubricant cup inpump shaft is full).

O. Relieve all pressure and back regulators out tozero.

12. MAINTENANCE—The spray gun and supportequipment represent a considerable investment. Toprotect the investment, it is important to implement aplanned maintenance program. It should include thefollowing:

A. An inventory of spare parts for all spray guns,pumps, hoses, catalyst injector or catalyst slave

pump to include:

1) Air cap, nozzle and needle.2) Packings and gaskets.3) Extra hoses—fittings.4) Extra gauges.

B. Be in constant awareness of the following:

1) Catalyst flow.2) Condition of all hoses, both gel coat and

catalyst. No kinks or frayed hoses.3) Spray pattern and technique.4) Contamination. If present, remove.5) Use of proper protective equipment.

C. The daily checklist for the beginning of eachshift should include:

1) Drain water traps morning, noon andafternoon (more if needed).

2) Mix gel coat (just enough to keep resin andstyrene mixed in). Do not overmix gel coats.Overmixing breaks down gel coat viscosity,increasing tendencies to sag, and causesstyrene loss, which could contribute toporosity. Gel coats should be mixed once aday, for 10 minutes. The gel coat should bemixed to the sides of the container with theleast amount of turbulence possible. Do notuse air bubbling for mixing gel coat. It is noteffective and only serves as a source forpossible contamination.

3) Inventory gel coat for day’s use. Check cata-lyst level. Always add catalyst which is atroom temperature. If using a slave armcatalyst system, check for air bubbles in thecatalyst line. Disconnect catalyst pump andhand pump until resistance is felt on both upand down strokes, or until proper pressure isreached on catalyst gauge (if the systemhas one).

4) Start pumps with regulator backed all theway out. Open valve and charge air slowly,checking for leaks. Do not let the pumpcycle (both strokes) more than one persecond.

The daily checklist continued:5) Shut down.

a) Turn off all air pressures and backregulator out.



Page 24 of 30

b) Bleed lines.c) Store pump shaft down to keep it wet.d) Check for material and catalyst leaks.

6) Clean up. Remove spray tips, clean, thenstore safely. Lightly grease all threads. If thetips and cap are placed in solvent overnight,make sure it is clean solvent.

7) Secure the area. Remove all solvents andcheck for hot spots. Remove and properlydispose of any collections of catalyzedmaterial or catalyst/materials combinations.

D. Weekly checklist should include:

1) Calibrate each spray gun for material flow.2) Calibrate each catalyzer or catalyst slave

pump for catalyst flow.3) Check gel time of gel coat through the gun

versus gel time of known control.4) Clean filter screens.

13. EQUIPMENT TROUBLESHOOTING—The majority

of polyesters used today are sprayed or pumped throughsemi-automatic equipment. The care and operation ofthis equipment will determine whether or not thepolyester will achieve its maximum properties andperformance. Fabrication equipment operators must betrained in how to use and maintain their equipment.

Anyone who uses spray equipment should have (andread) all the literature available from the manufacturer ofthe equipment. This includes warnings, parts diagrams,set up instructions, operating instructions, maintenancerequirements, safety and trouble shooting guides.

If this information has not been obtained or if a questionarises, call or write both the company from whom theequipment has been purchased and the manufacturer.They will help because they want the equipment usedefficiently, correctly and safely. Also, they will havegeneral literature on spraying, and technical servicepeople to help.

EQUIPMENT TROUBLESHOOTING—SUGGESTED CAUSES AND REMEDIES

PROBLEM—GEL COAT/SPRAY SUGGESTED CAUSES AND REMEDIES

Atomization poor (large droplets) ..... Check air pressure, length of hose, hose diameter (which may be too small), clogged or worn

nozzle or air cap, check if valves are stuck, too much fluid flow, regulator not working properly.

Catalyst injector balls drop ............... Bottom needle valve almost closed and vibrates, filter plugged, not enough CFM’s.

Catalyst injector balls overshoot ...... Top valve wide open, turn 1½ turns in—(Binks Injector).

Catalyst injector ball goes out of sight

when pressured ............................... Catalyst level too low—insert special gasket with .013 hole over delivery tube (Binks injector),

air in flow tube.

Catalyst injector balls fluctuating ..... Catalyst needle valve vibrating or too close to seat—open or tighten packing, not enough or

fluctuating CFM’s, dirty catalyst filter.

Catalyst valve—burst of catalyst ...... Weak spring due to aging. If Binks, use Plug Groove valve at the gun. If hose within a hose,

check for broken catalyst line.

Cavitating pump—sucks air.............. Remove siphon tube, put pump directly into resin—if pumps okay—cavitating due to siphon

system leak, pump too small, cold or high viscosity.

Check ball stuck .............................. Residue after flushing, vapor lock. Use piece of wood to free ball or tap side of pump.

Drips (Gun):

Fluid ..................................

Catalyst .............................

Solvent ..............................

Worn, clogged or bent needle, seating adjustment of needle, overspray on gun, worn packings

or seals, loose connection.

Worn seat or seals, damaged air valve, trigger out of adjustment, overspray on gun, loose

connection, clogged valve or seat, gun head not aligned to gun body, fan control may trap

catalyst in dead air space and drip catalyst out of air horns.

Clogged or worn valve, worn seals, sticking needle or button.

Gelled hose ..................................... Bad fluid nozzle, bad seat.



Page 25 of 30


Material (none on downstroke) .........

Material (none on upstroke).............. Foot valve, spring, spring retainer or foot valve ball worn or dirty.

Pattern of spray off to one side......... Piston cups, piston ball or pump cylinder worn.

Plugged filter screen......................... Partly clogged air cap, damaged nozzle, worn nozzle or air cap, bent or worn fluid needle.

Pump cycles when gun not in use ... Seedy or partly gelled batch, trash from material falling off pump when placed in new drum;

due to normal buildup, screens and pumps must be cleaned periodically; dirty surge chamber.

Shaft of pump drops an inch or two—

shudders...........................................

Worn piston cups, bottom check ball not seating.

PROBLEM—GEL COAT/SPRAY Starved pump—check filters or worn internal packings. Check for worn packing by stopping

pump at top of stroke—if with no material flow shaft creeps down, packing is worn.

Shaft of pump (material coming up

around) ............................................

SUGGESTED CAUSES AND REMEDIES

Siphon wand jumps ......................... Loose or worn seals—clean and tighten, stop pump in down position when system not in use,

worn shaft.

Slow gel time and/or cure ................ Dirt on check ball in pump.

Surging:

Material .............................

Catalyst .............................

Check catalyst and material flow, oil or water contamination. Check gun trigger for proper

activation. If slave pump, check for air bubbles.

Tails (airless):

Material .............................

Catalyst .............................

Inconsistent or low air pressure on pump, worn or loose pump packing, out of material, sucking

air through loose connection, balls not seating in pump (dives on down stroke —bottom ball;

fast upward stroke—top ball; flush pump), filter plugged, siphon line has air leak, screens

plugged, too much material flow, cold or high viscosity, plugged surge chamber.

Inconsistent or low air pressure, out of catalyst, check valve sticking in gun or catalyzer, loose

connection, screen plugged. If Binks equipment install Plug-Groove valve at the gun, keep

hoses straight rather than coiled.

Tips spitting or trigger will not shut off

...................................................... Pump pressure too low, worn tip, too large of tip, viscosity too high.

Worn tip, low pressure, wrong tip, viscosity too high, too large a fan.

Trigger stiff....................................... Worn seat or worn needle or weak spring, check packing.

Water in air lines.............................. Bent needle, bent trigger, worn needle guide.

Worn packings.................................

No extractor, extractor too close to compressor—should be no closer than 25 ft, all take offs

from main line should come off the top.

Fan pattern width varies on the up

stroke versus the down stroke ........ Pump overheating from being undersized, high pressure or pumping without any material, do

not let pumps jackhammer—no more than 1 cycle (both strokes) per second—use glass-

reinforced Teflon® packings. Keep idle pump shaft in down position to keep dried material from



Page 26 of 30

damaging packings.

Chunks in the filter larger than the

mesh of the strainer on the pickup

tube ................................................

Worn inner packing—replace.

Tails (non-atomized)......................

Gelled material in the surge chamber or pickup hose—clean or replace.

Catalyst pump feels spongy when

hand pumping..................................

Use larger tip or hose; use inline heater.

Catalyst gauge pressure drops when

gun not in use ................................. Trapped air pocket—open and close bypass, or pull trigger and pump up again.

Always remember the investment in the equipment andthat it was purchased to do an important job. If it is notmaintained and if worn parts are not replaced, theinvestment will be lost and the equipment will not do thejob for which it was selected and purchased.

One way to determine if a cure-related problem iscaused by material or equipment is to make a small testpart where the catalyst is mixed directly in the gel coat. Ifthis part does not exhibit the problem, then the cause ismore likely in the equipment or operator. Another way tocheck is to run a different batch of material through theequipment; however, this could generate bad parts,making the first test method preferable.

A list of some of the more common problems that canoccur with fabrication equipment follows. Since there aremany different types of equipment in use, it is impossibleto cover each one individually or to list all the possibleproblems or solutions. See the manufacturer’s literaturefor the particular type of equipment in use, or contact themanufacturer.

14. ADDITIONAL INFORMATION ON EQUIPMENT

A. If pump packing is too tight it will cold flow and

there will be strings at the edges of the packing.

B. Always put catalyst tip on bottom so catalystdoes not spray on glass.

C. Pre-orifice or insert—softens spray (lessforce); in some cases requires less pressure forproper breakup. NOTE: Use same size (or smaller)insert than tip.

D. To tighten upper packings, relieve pressure,tighten 1/8 turn at a time, run pump five strokes andrepeat, until no leak under pressure.

E. Catalyst condenses out of atomizing air in thehose in 10 to 15 minutes, (system at rest).

F. When ordering gun, specify nozzle and air cap.

G. Transfer pumps go through bung 4 to 1, 8 to 1only.

H. Binks pump—lower screen: 30 mesh; upperfilter: 50 mesh. Upper filter is half the orifice size.

I. Starting pump—open bypass until flow issteady.

J. To prevent leaks, avoid swivel fittings.

K. Compressor electric—1 horsepower isapproximately four CFM.

L. Quick disconnect restricts air flow.

M. Catalyst tip angle—same as material—wantequal fan pattern.

N. When spraying—pull trigger all the way (it’s allor nothing—no partial flow).

O. Lubricant—can use Vaseline.

P. Never insert a sharp object or probe into tiporifices. Blow out with compressed air from the frontof the tip to prevent lodged particle from becomingmore deeply lodged in orifice.

Q. Ask the equipment manufacturer about glass-filled fluid packings for pumping polyesters.

R. Always install shut-off valves in combinationwith fluid quick connects.

S. Always flush a filled system (resin/styrene) withunfilled resin, then solvent. Then always clean the



Page 27 of 30


filter.

T. Use water-soluble grease in between chevronpackings to reduce resin buildup between them.

15. EQUIPMENT SUPPLIERS—Following is a partiallist of equipment suppliers. They have many detailedbooklets on spraying and equipment. Write (or call)these suppliers and ask for their literature andrecommendations.

A. Complete systems

ITW-Binks-Polycraft195 International Blvd.Glendale Heights, IL 60139Ph: 630-237-5006Fax: 630-248-0838

Glas-Craft, Inc.5845 West 82nd St., Ste 102Indianapolis, IN 46278Ph: 317-875-5592Fax: 317-875-5456www.glascraft.com

GS Manufacturing985 W. 18th St.Costa Mesa, CA 92672Ph: 949-642-1500Fax: 949-631-6770www.gsmfg.com

Magnum Venus Products5148 113th Ave. NorthClearwater, FL 33760Ph: 727-573-2955Fax: 727-571-3636www.mvpind.com

B. Pumps only

The ARO CorporationOne ARO CenterBryan, OH 43508Ph: 419-636-4242www.hydraulic-supply.com

GRACOP.O. Box 1441Minneapolis, MN 55440Ph: 612-623-6000www.graco.com



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Page 30 of 30

OPEN MOLDING: Conventional Gel Coat—Application




2. Overview

3. Material Preparation

4. Equipment and Calibration

5. Spray Operators

6. General Spray Methods

7. Spray Methods for Particular Parts

8. Brushing Gel Coat

1. INTRODUCTION—Proper application of gel coat iscritical to producing cosmetically appealing and durableparts. Improperly applied gel coat increases the cost ofthe part. The amount of additional cost incurred dependson the number of rejected parts as well as the effortrequired to rework the parts. Making the investment ofproperly applying the gel coat can pay big dividends byreducing rework and scrap. Proper gel coat applicationincludes material preparation, equipment calibration, useof trained spray operators and appropriate spraymethods.

2. OVERVIEW—A conventional gel coat is applied withspray equipment as described in Chapter II.3 of this partof the guide. Brushing of gel coats is not recommended.The following information assumes that the proper gelcoat spray equipment has been selected and thatequipment is being properly maintained.

The ideal catalyst level for most gel coats is 1.8 percentat 77ºF (25ºC). However, the catalyst level can be variedbetween 1.2 percent and 3 percent to compensate forspecific shop conditions. Catalyst levels below 1.2percent or above 3 percent should not be used as thecure of the gel coat can be hindered permanently. Referto product data sheets for specific catalystrecommendations. There are a number of catalystsavailable for both resins and gel coats. It is imperativethat the proper catalyst be selected. Only MEKP-basedcatalysts should be used in gel coats. Broadly speaking,

there are three active components in an MEKP-basedcatalyst. They are hydrogen peroxide, MEKP monomer,and MEKP dimer. Each of these components play a rolein the curing of unsaturated polyesters. Hydrogenperoxide initiates the gellation phase, but does very littlefor overall cure. MEKP monomer is involved in initialcure as well as overall cure. MEKP dimer is mainlyactive during the film cure stage of polymerization.Historically, catalysts with high levels of MEKP dimerhave been identified as more likely to cause porosity ingel coats. Environmental factors that may requirecatalyst range variation include temperature, humidity,material age, and catalyst brand or type. Manufacturersshould always verify gel times under specific plantconditions prior to gel coat usage.

The gel coat should be applied in three passes to a totalwet film thickness of 18 ± 2 mils thickness. A coating thatis too thin (under 12 mils) could cause undercure of thegel coat, while a film that is too thick (over 24 mils) couldcrack under flexing. Gel coat that is spray applied onvertical surfaces (using this multiple-pass procedure)typically will not sag due to the gel coat’s thixotropicproperties. The gel coat is also resistant to entrapping air(porosity) when spray applied per instructions.

Under normal conditions, gel coats are ready forlamination 45 to 60 minutes after catalyzation. Theactual time is dependent on temperature, humidity,catalyst type, catalyst concentration, and air movement.Low temperatures, low catalyst concentrations, and highhumidity retard gel and cure, meaning that longer timeswill be required before the gel coat is ready. A reliabletest to determine whether the gel coat is ready forlamination is to touch the film at the lowest part of themold. If no material transfers, it is ready for lay-up.

For optimum results, uniform catalyst mix must beachieved. Even with the equipment properly calibrated,problems can occur due to poorly atomized catalyst,surging problems with the gel coat or catalyst,contamination, and poor application procedures. Theseproblems will quickly negate all benefits of calibration.The equipment and application procedures must be



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OPEN MOLDING: Conventional Gel Coat—ApplicationCopyright 2008

OVERVIEW continued:monitored on a routine basis to ensure properapplication and cure of the gel coat. Inquire about andadhere to all equipment manufacturers’recommendations.

3. MATERIAL PREPARATION—Gel coat materialsare supplied as completely formulated products. Noadditional materials other than catalyst should be added.

Prior to use, gel coats should be mixed for 10 minutes toensure product consistency. The agitation level shouldallow for product movement all the way to the walls ofthe container, but with the least amount of turbulencepossible. Do not over-mix. Overmixing can break downthe thixotropy, increasing the tendency to sag.Overmixing can also cause styrene loss that maycontribute to porosity. Do not use air bubbling for mixing.Air bubbling is ineffective and only serves as a potentialsource for water or oil contamination.

Gel coats are designed for use at temperatures above60ºF. Below 60ºF, the viscosity, thixotropy, and cure ofthe gel coat are affected.

• The lower the temperature the higher theviscosity.

• The lower the temperature the lower thethixotropy.

• The lower the temperature the longer the geltime.

Catalyst viscosity also increases with decreasingtemperatures. This can influence catalyst injectorreadings.

These factors combine to affect flow rates andatomization as well as make sagging a possibility. Inaddition, the effect of cold weather on cure can result inpoor part cosmetics. The slower gel times and curetimes of gel coats in cold conditions can lead to postcurethat can be seen as print-through and/or distortion.

CCP has developed a few helpful hints to facilitate gelcoat usage during cold weather. These include:

• Calibration of the spray equipment, while alwaysimportant, is especially important during coldweather due to the increase in viscosity of thegel coat and catalyst.

• Allow ample time for warming and make sure tocheck material temperature prior to use. Drums

can take two to three days to warm, even insidea warm shop. In extremely cold weather, evenlonger warming periods may be needed (three tofour days). A cold floor will extend the warmingtime.

• If the plant has a cement floor, there should beinsulation (such as a wooden pallet) underneaththe material container. This procedure will keepthe material warmer by preventing the heat frombeing drawn out by the concrete.

• Review inventory very carefully and place orderswell in advance.

4. EQUIPMENT CALIBRATION—General equipmentcalibration procedures for material delivery rate andcatalyst concentration are discussed below. See ChapterII.3 of this part of the guide for more detailed information.Always consult the equipment manufacturer for propercalibration of a particular type of equipment.

A. Batch Mix (Hot Pot)

1) Material Delivery Rate, or Fluid Supply—Thematerial delivery rate, or fluid supply, is therate that the gel coat flows from the spraygun. For optimum spray application, thematerial delivery rate should be between 1.5to 2.5 pounds per minute. Determine thematerial delivery rate as follows:

a) Back out the fluid needle adjustment,allowing maximum material deliverythrough the gun with the trigger pulled.

b) Weigh (in pounds) the container that willbe used to capture the gel coat .

c) Spray gel coat into the container for 30seconds.

d) Reweigh the container and gel coat inpounds.

e) Calculate material delivery rate inpounds per minute by subtracting theoriginal weight of the container from thecontainer and gel coat weight andmultiply this figure by 2.

Adjustment is made by changing the airpressure on the pressure pot or pump, or bychanging the orifice size. Material deliveryrate checks must be done by weight, notvolume, as gel coat densities vary.



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Batch Mix (Hot Pot) continued:

2) Atomizing Air—Correct air pressure isessential for proper material atomization. Tomeasure, read the pressure gauge attachedto the spray gun when the trigger is pulled(dynamic pressure) and the fan is fully open.Adjust as necessary to a minimum of 60 psi.This will help produce a porosity-free film.NOTE: Long air lines, small inside diameterair lines, or a number of fittings within theline can reduce the volume of air supplyingthe gun and can create erroneous results.Adjust as necessary for a minimum of 60psi.

3) Catalyst—Proper catalyst level isaccomplished by accurate weight orvolumetric measurement, so that thecatalyst level is exact as well as consistent.Always maintain the catalyst level between1.2 and 3 percent as needed, based onspecific plant conditions. NOTE: Catalystsused to cure polyester resins are veryreactive chemicals. Contact with manymaterials can cause decomposition that canpresent real fire hazards. Goodhousekeeping practices need to bemaintained at all times.

B. Catalyst Injection—With most catalyst injectionequipment, the peroxide catalyst is mixed externallywith the gel coat. If sprayed alone, it can travelseveral feet or more, eventually settling ontosurrounding surfaces. Accumulation of materials orother substances that can react with the catalysthave been the direct cause for fires in fiberglassshops. Cleanliness and constant removal and properdisposal of waste catalyst and contaminatedmaterials are the only safe ways to deal with thispotential hazard. Also, spraying only catalyst shouldbe avoided.

Solvent, either from diluting the catalyst as requiredfor some equipment or from cleanup operations,acts to increase the chances of an undesirablereaction.

Consult catalyst supplier, as well as Part Two on‘Health, Safety, and the Environment’ and CCPMaterial Safety Data Sheets for further information.

1) Material Delivery Rate or Fluid Supply—calibrate same as for batch mixing.

a) Air-atomized—1.5 to 2.5 pounds perminute.

b) Airless—1.5 to 3 pounds per minute forsmaller, intricate molds; 1.5 to 4 poundsper minute for large, open molds.

2) Atomizing Air (Air Volume)—Calibration isthe same as described for batch mixing withone exception: the catalyzer has a safetyvalve that will only allow 80 to 100 psi staticair pressure (no air flowing through the gun).The maximum pressure allowed by thesafety valve varies with the specificequipment. When maximum static pressureis reached, changing inside hose diameter,using a shorter hose, and minimizingrestrictions will permit more air volume.

Airless systems have no air atomization ofmaterial so there is no calibration of airpressure needed, or possible. Some airlesssystems do have air-atomized catalyst,which must be calibrated.

Air-assist airless systems require additionalatomizing air. It is important that air-assistair be kept as low as possible.

3) Catalyst—Specific equipmentmanufacturer’s recommendations should befollowed.

Calibration methods work as follows:

a) The intent is to collect some catalyzedgel coat just as it leaves the gun, andtime it to see how long it takes to gel.Comparing this gel time to that of asample that has been catalyzed byaccurately weighing the catalyst gives abasis of comparison for adjustingcatalyst settings. This should be done attwo different catalyst settings.

The procedure is to collect about 100grams of catalyzed gel coat in a smallcup, recording fluid pressure, settinglevel of the catalyst ball (or balls), andthe time. Similarly, collect 100 gramsthat is uncatalyzed, then weigh in the



Page 3 of 9


Catalyst Injection / Catalyst—Specific/A continued:

specified amount of catalyst, noting thetime of catalyzation. Adjust catalyzer bythe recommended method specific tothe equipment until the two gel times areequal. It should be noted that ballsettings are only relative guides and donot read in percent catalyst.

b) After gel coat has been calibrated(delivery rate), turn gel coat off. Thenrun delivery rate on the catalyst.Compare catalyst delivery to gel coatdelivery (percent catalyst) and adjustcatalyst percent as required to stay inproper range.

4) Do not assume a catalyst slave pump isworking properly. These also can becalibrated and should be monitoredcontinually. See Chapter II.3 on Gel CoatSpray Equipment in this part of the guide foradditional calibration information.

CCP’s gel coat (944-L-A72) containscatalyst indicator which is used to showefficiency of catalyst atomization and mix.

5. SPRAY OPERATOR—A spray gun is a precisiontool. It requires a skilled operator to efficiently apply thematerial. Many defects can be traced back to how thegel coat was applied. A poor spray application can bevery costly, so it is in the shop’s best interest to selectthe proper person as the spray operator and to followthrough with good training. A good spray operatorshould:

• Be conscientious.

• Have good coordination.

• Desire to do good work.

• Have some mechanical skill.

• Be patient.

• Possess good vision with no color blindness.

Good training is important because there aretechniques that must be mastered correctly—fromthe beginning—to avoid use of bad techniques andcostly shortcuts.

New spray operators should start out under directsupervision from competent personnel. They shouldbe assigned to spraying easy, noncritical parts.Progression to more difficult parts should be made inconjunction with the experience and ability of theindividual.

Free informational literature is available fromsuppliers of raw materials and equipmentmanufacturers. Training schools are offered by mostvendors.

6. GENERAL SPRAY METHODS

A. Check gun and lines for contamination such assolvent, water, or oil. Clean and correct asnecessary before spraying. Drain water frompressure regulator and traps daily; more often ifnecessary. If water is a constant problem, atemporary solution is to leave the bleed-off valve onthe water extractor open slightly. Water in the airlines can lead to expensive repairs to equipment andaffect the performance of the gel coat. It is best toavoid the problem (and less costly in the long run)by investing in a good drying system.

B. Check air pressures before spraying andadjust to achieve proper flow and breakup. Dropletsshould be no larger than 1/16 inch.

C. Always start spraying nearest the exhaust fanto minimize overspray that could be pulled onto themold.

D. If catalyst injection is used, make surecatalyst is flowing properly. Do not let raw catalystfall onto the mold or sprayed gel coat.

E. Check temperatures; adjust catalyst asnecessary (1.2 percent to 3 percent). Underextremely warm conditions, working times maybecome very short, necessitating the addition ofinhibitor to allow enough working time. Consult aCCP representative regarding what to add and theamount. Do not go below 1.2 percent catalyst orhigher than 3 percent.

F. Keep the spray gun perpendicular to the moldduring each stroke.



Page 4 of 9


G. Hold the spray gun 18 to 24 inches from themold when using conventional air-atomizedequipment; if using airless equipment, 24 to 36inches is the proper distance.

H. Do not arc the gun while spraying.

I. Keep the speed of each stroke so a full andconstant wet coat is applied.

J. The first spray pass should be a thincontinuous film (5 to 8 mils, dependent upontemperature, gel coat viscosity, and mold wax). Useof this technique helps to prevent porosity, resintearing, and mottling. About three passes areneeded to achieve a total thickness of 18 ± 2 mils.Spraying is a two handed operation—a spray gun inone hand, and mil gauge in the other.

K. Overlap strokes 50 percent.

L. Do not reach with a stroke. Stroke lengthshould be comfortable for the operator. Normally,this is 18 to 36 inches.

M. Begin spraying near an edge in a continuousstroke toward the opposite side. Each pass shouldbe parallel to the former, developing a uniformthickness. Subsequent passes should beperpendicular or diagonal to the preceding pattern toensure proper uniform coverage.

N. When practical, spray in sections from oneend, working continuously to the other. Avoid (asmuch as possible) overspray onto other parts of themold. Time lapse between spray passes or inspraying overlapping sections on large molds shouldnot be excessively delayed. Maintain a wet line (i.e.,cover up spray edges and overspray as soon aspossible).

O. Do not flood the gel coat on or spray with thefan sideways.

P. Use a mil gauge and touch up the tested areaafterward.

Q. Clean the gun immediately after using. Thisincludes any part of the equipment that may havereceived over-spray, such as hoses and gauges.

R. Inspect the gun regularly and replace wornparts.

S. Lubricate the gun and packings with lightmachine oil daily. Do not contaminate the gel coatwith oil.

T. Accidental contact with gel coat or catalyst canbe hazardous. In the event of contact involving bodyor clothing, clean the affected area immediately. Seeappropriate data sheets and labels for properprecautionary steps to follow.

U. Know the fire and toxic hazards of polyesters,catalyst, and the particular cleaning solvent beingused.

V. Have a regular preventive maintenanceprogram.

W. Place only one mold in the spray booth at atime. This prevents overspray onto other molds.

X. For all around end performance properties, awet film thickness of 18 ± 2 mils is recommended asideal. Films less than 12 mils may not cure properly,may be hard to patch, have more print-through, andbe more susceptible to water blisters. Films above24 mils may prerelease, trap porosity, or crack, andare more subject to weathering discoloration. Ifwater blisters are of a great concern (boat hulls), 20to 24 mils would perform better than a thinner film,but resistance to sag, porosity, and cracking couldsuffer. If weathering (yellowing from sunlight) is ofgreat concern, then thinner films of 12 to 16 milswould perform better, but patchability and resistanceto print-through and blister could suffer.

Y. Never reduce gel coat with a ‘conventional’paint or lacquer thinner.

Z. Disperse catalyst thoroughly. Poor distributioncauses uneven cure, color variation, blister potential,and premature release from mold before layup.

AA.Do not overcatalyze or undercatalyze. Excesscatalyst plasticizes gel coat, thus degrading its waterresistance and accelerating chalking and erosion.Poor cure also results from undercatalyzation. Apoorly cured gel coat is weak and will be degradedby weather.

Recommended catalyst level is: 1.2 to 3 percent (1.8percent at 77ºF (25ºC) ideal) MEKP (9 percentactive oxygen).



Page 5 of 9


BB.Apply a minimum of 16 mils of gel coat if glassfiber pattern is to be suppressed appreciably. Neverapply less than 12 mils as undercure may takeplace. The degree of protection against the outdoorelements is directly dependent on the amount of gelcoat deposited and its quality.

CC.Atomize the gel coat thoroughly when spraying.Low spray pressures will result in poor breakup andleave entrapped air in the gel coat. Entrapped aircauses blistering and high water absorption.

To check atomization, spray gel coat over glass to afilm thickness of 16 to 20 mils and hold over stronglight. Looking through the deposited gel coat willreveal any entrapped air.

DD.Do not apply gel coat over wet Polyvinyl Alcohol(PVA) Parting Film. Residual water in the film willretard gel coat cure and also cause ‘alligatoring.’

EE. Use the catalyzed gel coat within its working lifewith a proper allowance of time for cleanup ofequipment.

7. SPRAY METHODS FOR PARTICULAR PARTS—The shape and contour of each mold will dictate how itcan best be gel-coated. This should be considered inplanning where to start, where to finish, and howeverything in between will be handled. Unfamiliar partsshould be given serious consideration as to how they willbe sprayed before the actual application begins.Experience will show how it can be done better andmore efficiently.

Suggestions on spraying different configurations in amold follow:

A. Try to spray the most difficult area first andwork continuously out from it.

B. Keep overspray to a minimum.

C. Use a series of passes perpendicular ordiagonal to each other for more uniform thickness.

D. Keep laps (stroke) wet. This is called‘maintaining a wet line.’ Do not let a lap stay on themold more than 5 minutes without covering with a‘fresh’ lap. Alligatoring, and/or resin tearing, and‘splotches’ could occur when the part is sanded andbuffed.

E. Flat areas—These are easy to spray. Beginspraying near an edge in a continuous stroke toward

the other side. Each spray pass should be parallel tothe previous pass until a uniform thickness isachieved. Subsequent spray passes should beperpendicular or diagonal to the preceding pattern toensure proper uniform coverage.

F. Corners—Spray a pass down each side throughthe corner and work out about 12 inches from thecorners. Use short strokes, then spray adjacentareas.

G. Gentle Curves—Spray by arcing the gun tokeep it perpendicular to the working surface.

H. Channels—Spray the sides first. Most of thetime, overspray will cover the bottom.

I. Deep or Narrow Channels—Turn the fluidcontrol in to cut the flow down and narrow the fan. Ifusing airless or air-assist airless equipment,consider a smaller fan. Less fluid and air pressuremay be necessary, requiring more passes. Spray thesides first. Do not spray with the fan directly parallelto the channel. Keep the fan perpendicular to thechannel (or as much as is possible).

NOTE: If using catalyst injection, cutting back onmaterial flow will change the percent of catalystsupplied to the gel coat. Adjustment for propercatalyst level will be necessary.

Use a 1 quart pot gun to spray very difficult areas.

J. Use a rotating platform for round or smallparts.

8. BRUSHING GEL COATS—In general, the brushingof gel coats is not recommended. Brushing gel coats willtend to trap air as well as leaving visible brush marks onthe part surface. Also, gel coats are formulated withexcess monomer in order to facilitate spraying. Brushinggel coat will retain this excess monomer in the film.

There are a few instances where brushing gel coats iseither acceptable or unavoidable. An example of anacceptable brushing application is on the backside of alaminate in a non-critical and non-exposed area. This istypically done using an enamel or “air-drying” gel coat foraesthetic appeal and/or chemical resistance.

Brushing is also occasionally done in instances wheremold design makes it difficult or impossible to apply auniform thickness of gel coat by spraying. In thesecases, it is always desirable to prespray the area as well



Page 6 of 9


BRUSHING GEL COATS continued:as possible. While the gel coat is still wet, using light,long strokes, attempt to brush the overall film to athickness of 18-22 mils. Alternatively, it is possible toallow the initial film to gel and brush behind this withcatalyzed gel that has been sprayed into a container. Ineither case, the possibility of alligatoring is relativelyhigh.



Page 7 of 9




Page 8 of 9







Page 9 of 9

OPEN MOLDING: Conventional Gel Coat—Troubleshooting Guide

Composites

Applications Guide

Part Four, Chapter II.5

Copyright 2008In This Chapter1. Introduction2. Problem Diagnosis3. Common Gel Coat Problems and Solutions1. INTRODUCTION—Even under the best ofconditions, problems can occur due to accidents, mistakes, andunanticipated changes. Listed are some of the variousproblems that can occur and how to solve them. Alsoremember that the gel coat is affected by the laminate, andgood gel coat will not compensate for a poor laminate.2. PROBLEM DIAGNOSIS—To isolate and diagnosethe problem, give consideration to the following:A. What does the defect look like?B. Where does it occur? All over, random, isolatedside, or section?C. Is it on all parts, some of the parts, or just one?D. When did it first occur? Or when was it firstobserved?E. Does it match up to a defect in the mold?F. When were the defective parts sprayed?

1) Did it occur during a particular shift? Orfrom a particular spray operator?

2) Was it during a particular part of the day—when it was hot, cold, damp, or other?G. Did the problem occur through all spray stations orjust one in particular?H. Where does it occur? In the gel coat film? Againstthe mold? On the back side? Within the film?I. What is the code, batch number, and date of the gelcoat with which the problem is occurring? Were good partssprayed from this batch or drum?J. Was anything done differently, such as a change incatalyst level, spray operator, method of application, orweather conditions?K. How would someone else identify or describe thedefect?L. What were the weather conditions at the time thepart was sprayed?M. What corrective steps were taken and were theyeffective?N. Check the material or laminate that was applied toor on the gel coat.Listed on the following pages are common gel coat problemsand their usual solutions.Photographs illustrating many of these problems are alsoincluded.



Page 1 of 15


Copyright 2008

COMMON GEL COAT PROBLEMS AND SOLUTIONS

PROBLEM CAUSE SOLUTION OR ITEMS TO CHECK FOR

Air Bubble (see Photo #1, page 60) Air pockets Check rollout procedures.

Alligatoring—a wrinkling of the gelcoat, resembling alligator hide (seePhoto #2, page 60)

Before laminating

After or during lamination, or asecond application of gel coat

Raw catalyst Solvent ‘Cured’oversprayThin gel coatInsufficiently cured gel coat

Check for leaks or overspray.Do not reduce with solvents.Check for contamination. Maintain a wet line.

Use a minimum of 12 mils, wet. Discontinuous gelcoat film.Catalyst level too high or too low. Temperature toolow. Gel time too long. Time between coats orlamination insufficient. Moisture or contamination inthe mold.

Bleeding—one color shows onanother, typically when color striping(see Photo #3, page 60)

Laminate Bleed (cosmetic problemonly)

Striping gel coat sagging over‘cured’ gel coat

Monomer in laminating resinGel coat backside cure

Check sag resistance of ‘striping’ gel coat.Spray stripe coat as soon as possible. Spray thin filmof stripe color over the ‘wet’ base coat.Check for excessive monomer in laminating resin.Change gel coat.

Blisters (see Photos #4, 5, 6, page 60)Appear shortly after part is pulled,especially when put in sun

Appear after part in field

Water blisters

Unreacted catalyst or undercure

Solvent, water, or oil Airpockets Unreacted catalyst

Solvent, water or oil Various

Check percent catalyst, catalyst overspray, mixing,and leaks.Check air lines, material, and rollers.Check rollout.Check catalyst levels and distribution, filmthickness—18 ± 2 mils.Check air lines, materials, and rollers.See Part Four, Chapter VII.5 on ‘Blisters and Boils’tests.

Chalking (gel coats will oxidize/chalkover an extended period of time;degree of chalking is related directlyto the environment(see Photo #7, page 61)Dry, chalk-like appearance or depositon surface of gel coat (premature) (seePart Four, Chapter VII.2 on

Cure Under or overcatalyzation, producing incompletecure. Check air lines, material, and rollers. Check



Page 2 of 15

‘Weathering’) Contamination Insufficientbuffing

Poor mold condition

catalyst level, film thickness, water and solventcontamination.Surface soil picked up from atmosphere.Wipe buffed area with solvent rag. If gloss remains,area is okay. If gloss dulls down, part needs morebuffing.Reduce sanding and buffing requirement on parts bykeeping molds in good condition.

Checking (mud cracking)Single or groups of independent orcrescent-shaped cracks Poor integrity of the gel coat film Trapped vapor or incompatible liquid which blows

through the gel coat film on aging. Check catalystlevel. Check for water, solvent, etc. Chemical attack.Temperature extremes.

Craters—while spraying Chunks in the gel coatEquipment

Dirt in the gun or material. Material old and starting togel; rotate stock. Strain (filter) the gel coat.Clogged gun (clean). Improper atomizing air setting(too low).

Cracks (see Photos #8, 9, 10, page 61)Spider cracks radiating out from acentral point or in circles (reverseimpact)

Frontal impact Stress cracks(cracking in parallel lines)

Impact from laminate sideExcessive gel coat film thickness

Mold mark ImpactStress due to flexing

Mold mark

Check on handling and demolding procedures.Caution people about hammering on parts.Use a mil gauge and do not go over 24 mils.Defect in the mold.Be careful.Excessive gel coat thickness. Laminate too thin.Pulled too green; laminate undercured. Demolding orhandling procedure. Sticking in the mold.Defect in the mold.

DelaminationIn spots

Large area

Contamination

Gel coat too fully cured

Contamination Unbalancedlaminate

Check for dust, solvents, moisture, catalyst gettingonto the gel coat surface. Excess mold release waxfloating through to the gel coat surface, creating areasthat will not adhere.Check for high catalyst level. Letting the gel coat curetoo long, such as overnight; skin coat, rather thanleave on the mold for long periods of time. Excessmold release wax or wax in the gel coat.Solvent wiping, then waxing (around taped off areas),Dry fiberglass.

Dimples—in the gel coat surface(see Photo #11, page 61) Contamination

OtherCheck for water, solvent, or improperly mixedcatalyst. Overspray. Seedy resin. Excess binder on theglass mat.Thin laminate or gel coat. Very dry laminate. Pin air



Page 3 of 15


Copyright 2008

entrapped. Postcuring of the laminate.

Dull gloss—on the gel coatWhen part is pulled

When and after part is pulled

Rough mold Mold buildup

Polystyrene buildup

Dirt or dust on mold

Solvent or water Raw catalyst

Rough PVA or wet PVAInsufficiently cured gel

coat or laminate

Polish out mold.Wax and buff with cleaner. In most instances, what iscalled wax buildup is actually polystyrene buildup andshould be treated as such.Sand or scrub with brush and strong solvent; readprecaution on solvent before using. DO NOT USESTYRENE.Clean the mold. It is best to clean in the spray boothjust prior to gel coating. Time span should be as shortas possible between cleaning and gel coating. Use atack rag.Check for solvent or water. Drain water trapsregularly.Start catalyst flow from gun away from the mold.Only catalyzed gel coat should be sprayed into themold.Check spray technique.Correct excessive or insufficient catalyst level in gelcoat and laminate. Wait longer before pulling.Check for low temperature (minimum of 60ºF). Checkfor contamination: water, air or solvent.

Dull or soft spots—at random Gel coat uneven Catalyst poorlymixed into either gel coat and/orlaminate

Trapped solvent in gel coat and/orlaminateTrapped water in gel coat and/orlaminate Insufficientcatalyst

Poor breakup; use three passes.

Mix catalyst thoroughly or make equipment adjust-ments for good catalyst mix. Equipment surging(material pump and/or atomizing air). Improper cata-lyst settings (high or low). Gun held too close tomold.Check cleaning procedure. Check catalyst level withequipment using solvent-reduced catalyst.Drain lines and correct the problem.Confirm correct catalyst concentration.

Fading—see also water spotting (seePart Four, Chapter VII.2 on‘Weathering’)

Poorly cured gel coatImproper cleaners or

chemicals

Check catalyst levels and film thickness (18 ± 2 mils).Do not use strong alkaline or acidic cleaners.

Fiber pattern and distortion—in parts(see Photos #12 and #13, pages 61 and62)

Insufficient cure

Transferred from mold Glasscloth

Correct excessive or insufficient catalyst level in gelcoat and/or laminate. Wait longer before pulling, Donot pull while laminate still has heat. Check for lowtemperature. Check for contamination by water, oil, orsolvent.



Page 4 of 15

Woven roving

Gel coat too thin High exothermof laminate

Refinish mold.Too close to the gel coat. Should have two layers ofcured 1.5 oz. mat or equivalent chop between gel coatand cloth.Too close to the gel coat. Should have three layers ofcured 1.5 oz. mat or equivalent chop between gel coatand woven roving.Use 18 ± 2 mils, wet.Cure laminate more slowly. Laminate in stages. Uselower exotherm laminating resin.

Fisheyes (see Photo #14, page 62) Water, oil, or siliconecontaminationDust/dirt on moldGel coat film too thin Lowviscosity material

Drain air lines. Check mold release wax. Excessand/or fresh coat of wax is worse.Check lubricating materials used within theequipment. Use tack rag.Use 18 ± 2 mils in three passes.Old material—rotate stock.

Material gelled—in container Age Storage condition Use partial container first; keep covered.Use within storage limitations.

Jagged tape lines Gel coat starting to gel Use less catalyst (do not go below recommendedminimum). Use double tape process. Use good taperecommended for fine lines.

Pigment darting or specks(see Photo #15, page 62) Contamination Foreign particles Clean pump and lines.

Strain and keep material covered. Keep over-sprayminimized; be sure molds are clean; sprayperpendicular to mold surface.

Pigment separation or mottling(see Photo #16, page 62) Pigments separate from each other

Other

Check for contaminants such as water or solvent.Dirty equipment.Dry overspray. (Keep a wet line.) Excessively appliedgel coat causing sagging. Excessively high deliveryrates causing flooding onto the mold surface.

Pinholes (see Photo #17, page 62) Insufficient atomization Too high gel coat delivery rate. Not enough atomizingpressure.

Porosity (see Photo #18, page 62) Entrapped airWrong catalyst No catalyst

Gel coat film thickness

FormulationWater or solvent Pump cavitation

Excessive mixing

Wrong air pressure. Too high tens to yield fineporosity; too low will produce larger, surface porosity.Check gel coat vendor for recommendation.Check catalyst supply and alignment.Applied too thick; use 18 ± 2 mils wet. Apply in twoto three passes.Improper viscosity and/or resin solids. Check withvendor.Check for contamination.



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Copyright 2008

Check pump for air leaks.Mix once a day for 10 minutes only.

Prerelease of the gel coatDuring cure, causing obvious surfacedistortion and low gloss(see Photos #19, 20, page 63)

Occurring after cure; observed asvisible sharp distinct line (will notnecessarily feel line) with increasedfiber pattern on the side of the line thatpulled away—sometimes referred toas ‘heat’ or ‘shrink’ marks

Wrong catalyst High catalystlevel Low catalyst level

Uneven and/or too thickfilmGel coat allowed to cure too long

Gel coat resin solids too low

Uneven cure Mold releaseClay

Too long of cure Laminate curingtoo fastWrong type resin Laminate curinguneven

Refer to CCP-recommended catalyst list.Calibrate equipment and decrease catalyst.Calibrate equipment and increase catalyst.Check thickness, not to exceed 24 mils, wet. Ensure aconsistent film thickness.Gel coat should not be allowed to set on the mold formore than a few hours without laminating at least askin coat. Varies with temperature—should belaminated same day.Check with manufacturer; do not add styrene withouttheir approval.Improperly dispersed catalyst.Type and amount on the mold.Some clays cause an oily residue and prerelease.Change type of clay, dust the clay with a very finepowder or overspray with PVA.Laminate sooner—don’t lap or jar the mold.Check for proper catalyst level. Build laminate instages.Too high in exotherm.Low resin solids. Uneven laminate thickness. Checkresin-to-glass ratio. Resin drainout or puddling.

Resin tearing—or resin separation(see Photo # 21, page 62) Pigments separate from resin

ApplicationCheck for sources of water contamination.Avoid overspray. Improper spray techniques createexcessive overspray, droplets and flooding. Can beaggravated by long gel time and sagging. Do notallow overspray to dry; keep a wet line.

Sags and runs Excessive gel coat SpraytechniquesLow viscosity

Mold wax Other

Apply 18 ± 2 mils, wet.Atomizing air is pushing and blowing the gel coat.Not enough styrene is being volatilized.Check viscosity and thixotropic properties. Over-agitated. Material was reduced, but should not havebeen.Silicone content too high.Jarring the mold before gelation.

Softness Soft gel coat film which can beeasily matted

Incomplete cure of gel coat.Check catalyst levels, contaminants, and filmthickness.



Page 6 of 15

Splotches after demolding(see Photo #22, page 62) Solvent contamination Ensure that all solvent has been flushed out of spray

equipment lines. For internal mix equipment, ensurethat solvent flush line is not leaking.

Splotches after parts are sanded andbuffed—also referred to as ‘leathery,’pebbly,’ ‘chicken skin’ Overspray Not maintaining

a wet line CureDo not allow overspray to accumulate.Spray laps within five minutes.The total film must cure as a total homogenous filmrather than several independently cured thin films.

Water spotting—see also fading(see Photo # 23, page 62) Usually caused by exposure with a

com-bination of excessive heat andmoisture

Poorly cured gel coat Certainchemical treatments such aschlorine and/or cleaners

Exposure of parts tomoisture too quickly afterfabrication

Use only a product recommended for the particularapplication. Improper shrink-wrap. Use only a product(and recommended procedures) applicable to gelcoats.Check for both over and undercatalyzation.

Misuse of these chemicals.

Allow one week ambient cure before service.

Yellowing of gel coat—gel coatyellows rapidly and unevenly whenexposed to sunlight and/or heat andmoisture; see Part Four, Chapter VII.2on ‘Weathering’ (see Photo # 24, page63)

Polystyrene/wax buildup on themold which has transferred to thepart during moldingInadequate gel coat cure:Improper catalyzation whichresults in inadequate cure of gelcoat

Contamination such as solvent,moisture, or oil

Improper or unauthorizedadjustment of the gel coat

Cold temperature duringapplication

Perform regular mold-cleaning program. Do not cleanmold with styrene or used, dirty, or reclaimed solvent.

Check catalyst (bad or old lot batch) and catalystlevel. Use only a recommended catalyst and maintainthe proper level of catalyzation. (See the product datasheet.)These contaminants will affect the gel coat’s cure.Look for moisture or oil in air lines, moisture or othercontaminants in solvents used to cut the catalyst orother sources of contamination.Do not add any material (other than the recommendedmethyl ethyl ketone peroxide catalyst) to the gel coatwithout the advice of a CCP representative. Theaddition of solvents or excessive additions of styrene,inhibitors, accelerators, etc., will adversely affect thegel coat’s cure and therefore its resistance toyellowing. Contact a CCP representative if adjustmentseems necessary.Do not apply gel coat at temperatures below 60ºF;permanent undercure of gel coat may result.



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Copyright 2008

Old material

Film cure inhibited by styrenevaporsPrerelease

Excessively hot resin-richlaminates

Resin tearing

Uneven gel coat film thickness

Cleaning the finished part with analkaline cleaner

Holding gun too close to the moldSpraying in one passInsufficient atomization

Old material may be slow in gel and cure and willneed adjustment. Consult a CCP representative.Provide adequate air circulation for ‘deep well’ areaswhere styrene vapors may collect.Most of the conditions which cause prerelease willalso result in unusual gel coat yellowing, i.e., unevengel coat thickness, uneven catalyzation, uneven filmgel and cure, etc. Check for and eliminate any pre-release causes.Good laminating techniques must be followed. This isespecially true in deep well areas where the gel coat isnot likely to cure adequately. Unusually ‘hot’laminates at this point in the gel coat’s cure may resultin permanent undercure and more yellowing of the gelcoat.Overspray, excessive film build, flooding, or contam-ination, all of which can result in vehicle/pigmentseparation. A concentration of the gel coat vehicle onthe surface of the part will result in more rapidyellowing of the finished part.Avoid flooding the gel coat or applying excessivelythick gel coat. Maintain the recommended 18 ± 2 milswet film coverage. Excessively thick gel coat filmswill yellow more.Do not use any strong alkaline cleaner (such asammonia or other cleaner having a pH greater thannine) for cleaning a gel coat surface. A weathered gelcoat can be yellowed by such cleaners.Maintain proper distance.Spray in multiple passes.Gel coat must be atomized to fine particles.

1. Air Bubble 2. Alligatoring(Yellowing area indicates resin)



Page 8 of 15

3. Bleeding

5. Blisters – Osmotics –(Small blisters – gel coat; large – laminate)

4. Blisters(Caused by catalyst drop)

6. Catalyst Drop Gassing(Can likely blister as in Photo #4)



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Copyright 2008

7. Chalking

9. Cracks – Frontal Impact

11. Dimples

8. Cracks – Reverse Impact(Spider/Star)

10. Cracks - Stress

12. Distortion(Top panel shows distortion)



Page 10 of 15

13. Fiber Pattern & Distortion(Note also exhibits dimples)

15. Pigment Darting

17. Pinholes

14. Fisheyes

16. Pigment/Color Separations

18. PorosityMagnified 10x)



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Copyright 2008

19. Prerelease(Gel coat, before lamination)

21. Resin Tearing

23. Water Spotting

20. Prerelease(Gel coat, during or after lamination)

22. Splotches After Demolding

24. Yellowing Caused by Thick Gel Coat(Inset shows 55 mil thickness of white gel coat)



Page 12 of 15



Page 13 of 15


Copyright 2008



Page 14 of 15







Page 15 of 15

OPEN MOLDING: SpecialtyGel Coats—Conductive Sanding


Part Four, Chapter III.1Copyright 2008

In This Chapter1. Description

2. Application

1. DESCRIPTION—CCP conductive sanding gel coatshave been used for several years in compositeconstruction to enable electrostatic post painting of FRPparts. They are offered for both open mold and RTMprocesses. They may also be used as a gel-coatedsurface to facilitate static electricity drainoff (with propergrounding provided).

These products are available only in black. Conductivitycomes from carbon particles, which are black. The liquidmaterial will normally yield a maximum resistance of0.10 megohms when tested by an ITW Ransburg#76634 meter. Users should determine that theproduct’s conductivity meets the intended use.

These conductive sanding gel coats are made fromresilient isophthalic polymers to meet normalflexing/fitting demands after paint baking. They allowquick powdering-sanding and surface preparation. Theyexhibit good chemical resistance and are consideredvery serviceable in a saltwater environment.

While the gel coat is only part of the composite/laminatestructure, it must participate in the processing andservice conditions of the total composite. Parts madewith these conductive gel coats can withstandtemperature elevations to 180ºF (82ºC), but normaloperating temperature range is considered 0ºF to 120ºF(-18ºC to 49ºC). The cured gel coat will endure the lowertemperatures of this range but can crack if stressedsignificantly. Temperatures as high as 285ºF (141ºC) for30 minutes are withstood, but customers should expectsome pinhole blowing and accompanying spew fromtrapped air pockets within the sanded composite.

These gel coats are ready to use and require only theaddition of an appropriate methyl ethyl ketone peroxide(MEKP) to cure.

These gel coats will chalk when exposed to directsunlight and are not designed (nor recommended) forconstant water immersion parts.

Conductive surface coats (or enamels) can be madefrom these products by adding 2.5 percent 970-C-949wax solution.

2. APPLICATION—Conductive sanding gel coats aregenerally formulated for both airless and conventionalspray application. Brushing or rolling is notrecommended. Refer to Part Four, Chapter IIConventional Gel Coat, sections on Application, andSpray Equipment, for additional specificrecommendations.

Pits, pinholes, and porosity are, of course, verydetrimental in a sanding gel coat which is to be postpainted. It is important not to spray any of these defectsinto the film. Keeping the equipment properly calibrated(gel coat delivery/atomization and catalystdelivery/atomization) is important as is maintaining aminimum temperature of 60ºF (16ºC) (material, mold,and ambient) and applying the gel coat in at least threesmoothly sprayed 6 mil coats using the appropriatespray distance.

CCP recommends a gel coat delivery rate of no morethan 2.5 pounds per minute with conventional air-atomized equipment, and no more than 4 pounds perminute with airless equipment.

For optimum results, uniform catalyst mix must beachieved. Even with the equipment properly calibrated,potential problems can occur due to: poorly atomizedcatalyst; surging problems (gel coat or catalyst); poor tipalignment (catalyst to gel coat mix); contamination; andpoor application procedures, which will quickly negate allbenefits of calibration. The equipment (and applicationprocedures) must be monitored on a routine basis toensure proper application and cure of the gel coat. Askabout and adhere to most equipment manufacturer’srecommendations.



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OPEN MOLDING: Specialty Gel Coats—Conductive SandingCopyright 2008

APPLICATION continued:For best overall end performance properties, a wet filmthickness of 18 ± 2 mils is recommended as ideal. Filmsless than 12 mils will have less conductivity, may notcure properly, may be hard to patch, have more print-through, and are more susceptible to water blisters.Films above 24 mils may pre-release, trap porosity, andcrack.

Proper mold maintenance is important. Althoughconductive gel coats have excellent patching properties,minimal repair work is always desirable.



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OPEN MOLDING: Specialty Gel Coats—Conductive SandingCopyright 2008



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Page 4 of 4

OPEN MOLDING: Specialty Gel Coats—Metalflake




2. Selecting the Right Gel Coat

3. Recommended Application Procedure

4. Equipment

5. Unique Problems

6. pH Test for Metalflake

7. Patching Metalflake

1. INTRODUCTION—There is a unique appeal to ametalflake finish. When done right, it is eye-catching.The colors glisten, changing with shadows or light. Onclose examination, there is a distinctive richness anddepth of luster.

Use of a metalflake finish will require increasedinvestment in materials and labor, but if the design of thepart warrants such an unusual finish, then the extra timeand care should be taken to ensure the quality of thefinal product.

Metalflake suppliers recommend epoxy-coatedaluminum and polyester flakes for use with polyesters.There are polyester flakes coated with epoxy or acrylic.Polyester flake generally makes better looking, morebrilliant part than aluminum metalflake, but also costsmore.

Polyester flake density is closer to that of clear gel coat.However, an advantage of aluminum flake is its solubilityin muriatic acid, which is a help on patching. Muriaticacid will not dissolve polyester flake.

Questions about metalflake should be directed to themetalflake supplier.

2. SELECTING THE RIGHT GEL COAT—The gel coatmust be clear so that the full brilliance of each metalparticle is visible in the final product. Clear gel coats areformulated for various specific applications, whichinclude use with metalflake. Always specify a marineclear (rather than marble clear).

Cook Composites and Polymers Company produces

several marine clear gel coats suitable for metalflakeapplication. CCP’s marine clear gel coats are formulatedfor superior UV resistance and flexibility. Gel coats withflexibility and lower viscosity are preferred for metalflakeapplications. Contact a CCP sales representative formore specific recommendations.

3. RECOMMENDED APPLICATION PROCEDURE

A. Clear gel coat should be catalyzed at therecommended level; consult individual data sheetsfor these specifications. Over or undercatalyzationcan cause premature yellowing, cracking, or crazing,or can cause physical deficiencies in surface glossor general surface appearance.

Spraying uncatalyzed clear gel coat is not goodpractice. If sprayed too thick, the result can be anundercured film that will contribute to a distortedsurface. In addition, an uncatalyzed film can beprone to porosity.

B. To ensure an enriched depth of metalflake,catalyzed clear gel coat should be applied 12 to 14mils, wet, in two to three passes, allowing sufficienttime for air release between each pass. This coat ofclear helps prevent a rippled surface and protectsthe metalflake particles from the elements. Lessthan 12 to 14 mils can result in an undercured film,which will have greater alligatoring potential. Also, itis much harder to patch metalflake when there islittle or no clear. More than 12 to 14 mils caninterfere with clarity and produce a heavy gel coatthickness, which is more susceptible to cracking,crazing, and poor weathering.

C. Once the clear coat is ready, the metalflakecoat may be applied. Opinions vary on how muchmetalflake to use. Normal range is 10 to 20 percentby weight. If greater hide or more brilliant color isdesired, these may be achieved by mixingproportions of fine and coarse flake. It is important toremember when catalyzing clear and metalflakemixtures to subtract the weight of the metalflake; forexample, with a 1,000 gram total mixture, if 20percent is metalflake, then only 800 grams of the



Page 1 of 7

OPEN MOLDING: Specialty Gel Coats—MetalflakeCopyright 2008

RECOMMENDED APPLICATION PROCEDUREcontinued:

total mix will require catalyst. It should be noted thatsufficient residual chemicals may remain on themetalflake, so that if higher percentages are used, geland cure of the clear gel coat may be retarded.Normally, a reduction in metalflake can help correct thisproblem. Also, if pressure pot equipment is used, gelcoat and flake mix should not be allowed to sit more than60 minutes before being used. Longer contact time cancause gel/cure extension. Poor cure results from thisextension. Poor cure will be observed as a grainy orrippled distortion. Reduced gloss may also be observed.

Catalyzation of the metalflake gel coat should meetmaterial specification, with application at 12 to 20mils, wet.

D. Generally, regardless of how much metalflake isadded to the gel coat, it will not (and should not)produce total hide. Orientation of the flakes willalways produce small voids in the color.

If not addressed, these voids can distract from thetotal effect, leaving a flatness in the finish. This canbe overcome with a procedure that further enhancesthe final appearance. The procedure is to apply apigmented layer directly behind the metalflake. Notonly is complete hide assured with this procedure,but use of a contrasting color (usually black), willprovide greater depth and eye-catching appeal.

If everything has been done correctly to this point,about 30 mils of gel coat have been applied to themold. More gel coat could create problems ofcracking and crazing due to excess total gel coatthickness.

Two methods are commonly used. The mostcommon is wet-on-wet.

1) Wet-On-Wet Procedure

Although CCP recommends that each coatcures before the next coat is applied, metalflake hasbeen sprayed successfully using the wet-on-wettechnique. The advantage is in time saved. Theprocedure consists of spraying all coats on top ofone another without waiting for each coat to cure.There should be no lag time once spraying isstarted. The following problems can occur:

a) Alligatoring.

b) Blow through (blowing the metalflakethrough the first clear, or blowing the backup throughthe flake coat).

c) Metalflake rippling may increase.d) Checking (occurs when edges of the

flake are within the clear coat and immediately nextto the mold surface).

e) Stretch marks (occurs when the backupcoat cures much more quickly than the flake coat;worsened if the backup coat sags).

Proper catalyst levels must be maintained inall three coats.

2) Cured Procedure

a) Allow the clear to cure adequatelybefore applying the metalflake coat. Time will vary,depending upon a number of conditions, includingcatalyst type and concentration, temperature andhumidity. Cure should be such that the metalflakecoat does not cause the clear coat to alligator.

b) Once the initial coat of clear is ready,the metalflake coat can be applied.

c) After the metalflake coat has cured, thebackup coat is applied.

Laminate and allow a good cure before pulling. Nopull should be made until after the part hasexothermed and cooled to room temperature.Provide adequate heat, or an undercured part caninduce some surface rippling in the final part.Overnight cure is best.

4. EQUIPMENT—Conventional air-atomized sprayequipment (the kind suitable for spraying regular gelcoats) is sufficient, but some changes will be necessary.The metalflake tends to clog, so larger fluid tips andnozzles will be required. Fluid tip sizes in the range of0.090 inches to 0.110 inches should be sufficient.

High percentages of metalflake or larger metalflakeparticles can become trapped between the fluid nozzleand the needle. This can prevent the gun from shuttingoff properly. To prevent this, Binks has the MetalflakeNozzle Kit (#102-530) to fit its 7N gun.

Pressure pots are used instead of pumps for delivery tothe gun. The metalflake particles can be damaged bypumping action. In addition, these particles can createproblems with the pump and existing filters. Usually



Page 2 of 7


EQUIPMENT continued:

more than one specific color metalflake is used, sosmall-batch mixing of up to several gallons each provesto be the most practical means of application. Mixedbatches should not be allowed to sit for more than onehour before use.

Alternatively, metalflake can be applied with standardairless air-assist gel coat equipment, using a separatecontainer of metalflake that is fed to the gun head.

To use airless air-assist gel coat equipment, somemodifications are required. Gel coat and catalyst tipsmust be rotated 90 degrees, creating a horizontal ratherthan vertical spray pattern, similar to the fan pattern inchopped fiberglass. The gun head must be fitted with atop-mounted tube, allowing directional control of themetalflake, again similar to a chop chute. The bulk drymetalflake is in a hopper at the spray booth or carriedwith the operator in a backpack. If using a backpack, thetwo most common types are hard cylinders or softpouches. The gel coat gun must be modified with an airline, which can be fed to the backpack. Air from the gelcoat gun to the backpack ‘fluidizes’ the metalflake andcreates a pressure differential that forces flake down thedelivery tube, normally 3/8 inch to 1/2 inch in diameter tothe gun head. This method allows for coverage of amuch greater surface area than would be possible usinga pressure pot, allows the same tips to be used for clearcoat and metalflake coat, and is also a more efficientmethod, requiring no premixing.

5. UNIQUE PROBLEMS—Color change and blisteringof the metalflake film can be caused by a combination of:

• Metalflake• Catalyst (the higher the catalyst level, thegreater the problem)• Water

In the initial stages, the flake darkens and at the sametime exhibits less brilliance. As the color changeprogresses, the flakes seem to disappear. Since theflakes become transparent, the backup color will begin toshow through. The ultimate and final stage has beenreached when all flakes seem to disappear (they areactually transparent), when there is no luster orbrilliance, and when there is a dramatic color change.Magnification, about 10X, is very helpful to observe thisprocess.

This problem seems to occur only with epoxy-coated

polyester flake. Construction of this flake starts with apolyester film such as Mylar

®. Pure aluminum is

deposited onto the polyester film, providing an opaque,mirror-like surface.

An epoxy coating is then applied. This coating containscolorants.

The visible change results when the aluminum isdissolved from the flake. At first, light corrosion of thealuminum causes darkening and loss of luster. With alighted magnifying glass, this can be seen as a morerandom diffraction of light. In final stages, when all of thealuminum is dissolved, the flakes are transparent and ofa color representative of the colorant used in the epoxycoating and the color of the backup gel coat.

Continued exposure to water makes this problem showup. High humidity can be worse than immersion. Pure ordistilled water is more corrosive and worse than tapwater. With elevated temperatures, corrosion occurssooner.

MEK Peroxides are corrosive in the presence of bothwater and metalflake. Excessive amounts of catalystspeed the rate at which corrosion occurs. Raw catalystspots can cause dramatic and rapid changes. Catalystinjection equipment may not always provide evencatalyst dispersion, resulting in areas of concentratedcatalyst that will increase susceptibility to corrosion.

Maintaining recommended catalyst level with properlyfunctioning equipment is one precautionary step thefabricator can use to control and minimize this problem.The recommendation is that metalflake should becatalyzed and applied via the hot pot system (i.e., aknown amount of catalyst mixed into the gel coat).

If a particular operation will not allow use of the hot pot,then equipment should be calibrated weekly, or moreoften if:

• A new batch of gel coat is used• A new batch of catalyst is used• A new pump is used• A rebuilt pump is used• Any equipment malfunction has occurred• An extreme temperature change has occurred• New equipment is placed on the same air line• Pressures are changed• Tips are changed



Page 3 of 7


UNIQUE PROBLEMS continued:

Key people—such as the supervisor, lead person andspray person—should be advised of this potentiallydamaging problem occurring due to a high catalyst level.They should be knowledgeable about calibration and bewatchful for catalyst drops, excess catalyst, or a suddendecrease in gel coat flow.

6. pH TEST FOR METALFLAKE—The pH test can behelpful. This can be a standard incoming quality controltest, or specifically used to confirm problem lots ofmetalflake.

The procedure is simple. Mix an equal volume ofmetalflake with distilled water and let stand for 30minutes. Check with pH meter (preferred) or pH paper(available from chemical supply houses). Also check pHof the distilled water, which should show a pH 7. Any pHless than 7 indicates an acid solution. Stronger acidsolutions are indicated by lower pH, or simply a smallernumber.

Solutions with a pH 5 to 7 are generally trouble free.Batches of metalflake that show pH from 2 to 5 are morelikely to have gel/cure problems, and can be subject tofield discoloration.

7. PATCHING METALFLAKE—Metalflake is difficult topatch and requires more expertise and patience thanregular pigmented gel coats.

The clear coat is very important. The main problem withpatching metalflake is that when flake is sanded, color isremoved and the flake turns a bright silver. If a clear hasbeen applied, minor scratches can be sanded or buffedout. If the first clear is not used, no sanding can be doneuntil a clear spray patch is applied. It is the clear coatthat can be worked and sanded, not the flake coat.

Use only the same clear gel coat (marine type) that wasused to make the part. Do not use a gel coat intendedfor the manufacture of cultured marble.

CCP offers special patching thinners developedspecifically for patching metalflake. See the patchingthinners data sheet for product selection and specificinstructions.

A. Small spot patch.

1) Prepare the area by routing, sanding tofeather, and washing with solvent.

2) Brush with catalyzed accent color. Let dry.

3) Apply a small amount of catalyzed flake and

clear (approximately 15 percent flake and 85percent clear). Cover with a sweep made ofwaxed paper or cellophane. Strike acrossthe sweep as smoothly as possible.

4) Let cure overnight (due to inhibitiontendencies of the flake).

5) Sand with 600 grit paper.

6) Buff.

7) Wash with HYDROCHLORIC or MURIATICacid to dissolve any exposed flake (only ifworking with metalflake rather than polyesterflake). CAUTION: Hydrochloric (Muriatic)acid is very toxic and can be harmful ifnot properly handled. Always weargloves and protective glasses.

8) Wax.

B. Very small spot patch with no sanding.

1) Route area. Do not sand surrounding area.


3) Apply a small amount of catalyzed flake andclear. Cover with a sweep made of waxedpaper or cellophane. Strike across thesweep as smoothly and nearly flush aspossible.

4) Let cure overnight and remove paper.

5) Trim and clean with knife blade.

6) Wax.

C. Spot patch with clear overspray.

1) Prepare the area as for regular spot patch.


3) Apply a small amount of catalyzed flake andclear mix. Cover with a sweep made fromwaxed paper or cellophane. Strike acrossthe sweep as smoothly and nearly flush aspossible.

4) Let set overnight and remove paper.

5) Scuff and solvent-wash the area to preparefor spray patch.

6) Overspray with catalyzed clear gel coat.

7) Let cure minimum of 2 hours. Sand, buff,and wax.



Page 4 of 7


D. Spray patch.

1) After damaged area has been prepared,wash with solvent.

2) Mask off a large area around the repair.

3) Spray with catalyzed flake and clear mix(see patching thinner data sheet for productselection and specific instructions). Let cure for 2hours.

4) Overspray with clear, making sure to gobeyond the perimeter of the flake coat. Spray PVAor catalyzed PATCHAID

®on top of the clear for

better surface cure. Let dry overnight.

5) Sand, buff, and wax.

If clear gel coat was not used for the part, then clearmust be sprayed to provide a base coat to feather into.Scuff an area larger in size than the actual repair area.Use 600 grit sandpaper and be careful not to sand hardenough to turn the flake silver. Spray this area withcatalyzed clear and proceed with step D.3, previously.



Page 5 of 7




Page 6 of 7







Page 7 of 7

OPEN MOLDING: Specialty Gel Coats—Metallic




2. Application

3. Precaution

4. Exposure Performance

5. Metallic Effects

1. DESCRIPTION—Cook Composites and PolymersCompany offers a line of metallic gel coats for the FRPindustry. These gel coats are used in passenger,camper, utility, and recreation vehicles of thetransportation industry, as well as for decorativestructural components and marine vehicle surfaces.

These gel coats produce the small metallic sparklecommon in the automotive industry. These metallicparticles are smaller than typical metalflake and providea subtle brilliance and elegant appearance.

Normally, the colors and effects will not be quite asdramatic or as appealing as many of the automotive-typemetallic finishes.

True metal (metallic) pigments can cause very dramaticresults in a polyester such as a gel coat. The aluminumpastes can be used but usually cause the resin to gelovernight, so they must be added just prior to use.Copper-containing pigments can cause real problems,permanently inhibiting gel and/or cure. Percentages arelimited to about 10 percent by weight and may exhibitsome gel and cure inhibition. Colors will be duller andtheir durability may be substantially harmed.

The other type of pigments capable of producing ametallic effect are pearlescent pigments such as AfflairFlake pigments from E.M. Industries, Inc., or the Lusterpigments from Engelhard. Both achieve similar results;they differ mainly in color.

Usually, pearlescent pigments can be added in therange of 0.2 percent to 5 percent by weight to a neutralor clear gel coat. Neutral gel coats tend to work betterthan clears because they have less tendency to mottlewhen sprayed.

Some really exciting colors can be achieved by addingjust enough pigment concentrate to get a specific color.Of the tinted colors, black, blue, and maroon seem tooffer the more appealing shades in metallics.

Patching this type of gel coat can be difficult. Sags andpre-gel disturbance of the metallic film causes obviousdistortions in the surface appearance. Contact local FRPdistributors for metalflake, metallic, and pearlescentsupplies.

2. APPLICATION—Metallic gel coats are formulatedfor spray application. Brushing or rolling is notrecommended. (See also Part Four, Chapter II.4 onApplication.)

Changes in the setup of the spraying equipment and/orapplication technique lead to variances in metallic colorshades and patterns. To reproduce a metallic color, it isessential that the following be kept constant: sprayequipment, pot pressure, atomization pressure, anddistance from which the spray is applied.

A Binks 7N spray gun can be used. Setup should includea 63 PB air cap, 66 fluid nozzle, and 36 needle. The rateof delivery should be no more than 1.5 pounds of gelcoat per minute. Forty pounds of air pressure (measuredat the gun) is necessary to properly atomize the gel coat.Equipment suppliers offer container pots that willcontinually mix the gel coat to ensure proper dispersion.Keep the spray gun two to three feet from the molds.

Alternately, standard airless air-assist equipment can beused to apply metallic gel coats. With most metallic gelcoats a minimum orifice size of 0.021” is recommended.



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OPEN MOLDING: Specialty Gel Coats—MetallicCopyright 2008

APPLICATION continued:

Metallic gel coats use the same metallic pigments usedin automotive finishes. However, the differencesbetween urethane paints and gel coats in terms offormulation and application mean that the two systemswill never match each other perfectly. It should be notedthat material flow rate, spray distance, and spray anglemay all yield slightly different appearances.

If the patterns of the metallic on the finished part are notsatisfactory, a dust-coat approach may be used.Whether it is a ‘heavy dust’ or a ‘light dust’ is not asimportant as getting the dust coat consistent anduniform. A heavy dust will provide a different ultimateeffect than a light dust. If the gel coat is sprayed to anextremely inconsistent dust coat, these different effectswill be noticeable.

For optimum results, uniform catalyst mix must beachieved. Even with the equipment properly calibrated,problems can occur due to: poorly atomized catalyst;surging problems (gel coat or catalyst); poor tipalignment (catalyst to gel coat mix); contamination; andpoor application procedures, which will quickly negate allbenefits of calibration. The equipment (and applicationprocedures) must be monitored on a routine basis toensure proper application and cure of the gel coat.Inquire about and adhere to all equipmentmanufacturers’ recommendations.

For best overall performance properties, a wet filmthickness of 18 ± 2 mils is recommended as ideal. Filmsless than 12 mils may not cure properly, may be hard topatch, have more print-through, and may be moresusceptible to water blisters. Films that exceed 24 milsmay prerelease, trap porosity, or crack, and are moresubject to weathering discoloration. If water blisters areof a great concern (boat hulls), 20 to 24 mils thicknesswould perform better than a thinner film, but sag,porosity, and cracking resistance could suffer. Ifweathering (yellowing from sunlight, decks) is of greatconcern, then thinner films (12 to 16 mils) would performbetter, but patchability, print-through, and blisterresistance could suffer.

Proper mold maintenance is important. Minimal repairwork is always desirable. Sanding and compounding canhasten the chalking and loss of gloss of all gel coats.

Patching metallic gel coats is very difficult, and patchesare likely to be more noticeable than those for solidcolors. Fabricators may have to be content with somecolor and appearance differences between the patchand surrounding area, due to the sanding/polishingdisturbance of the metallic pigments.

3. PRECAUTION—Metallic gel coats may containaluminum pigments. Precautions for products thatcontain aluminum pigment must be exercised. Allequipment should be well grounded. Chlorinatedsolvents in contact with aluminum can cause anexplosion; refrain from cleaning the metallic sprayequipment with such solvents.

4. EXPOSURE PERFORMANCE—Metallic gel coatsexpose similarly to conventional solid gel coat colors.Chalk development and gloss loss will vary with metalliccontent. High metallic content gel coats maydemonstrate more rapid chalk development than othergel coats. Consult a CCP representative about specificformulations.

5. METALLIC EFFECTS—Flakes of aluminum,bronze, coated mica, copper, glass, iron oxide, andthermoplastic or thermoset plastic are used to impartmetallic effects. Type, size, concentration, orientation,transparency, and opacity of the flakes, along with thepresence of dyes or pigments, contribute to the overallcolor and appearance of metallic gel coats.



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OPEN MOLDING: Specialty Gel Coats—MetallicCopyright 2008



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Page 4 of 4

OPEN MOLDING: Specialty Gel Coats—Enamels



In This Chapter

1. Introduction

2. Surface Preparation

3. Application

4. Cure

5. Availability

6. Cleanup

1. INTRODUCTION—POLYCOR®

enamels areformulated to be used as topcoats (surface coats,interior gel coats) for FRP. They are very similar to gelcoats except that they cure tack-free.

Enamels are used like paint on FRP surfaces—a topcoatto seal and hide a substrate. Normally, enamels areused as interior finishes or to cover a laminate to providea colored surface. Enamels cannot be used like moldcontact gel coats because they contain wax and curetack-free, which could cause delamination. Along withproviding a tack-free surface, the wax in enamels helpsto suppress styrene evaporation. This reduces thevolatile organic content (VOC) emitted into the air.

Enamels can be made from isophthalic, ISO/NPG ororthophthalic base resin. Consult a CCP salesrepresentative for more information about a particularproduct.

Enamels are multi-mil surface coatings formulated foruse in boat and camper shell interiors.

Standard enamels should not be used for waterimmersion service. Contact a CCP sales representativefor recommendations if water immersion is required.

POLYCOR®

enamels produce a hard, tough, durable,flat finish with good water resistance characteristicswhen applied correctly.

2. SURFACE PREPARATION—With fiberglasslaminates such as boat and camper shell interiors:

A. POLYCOR®

enamel should be sprayed after the

laminate has cured and while it has a tacky surface.Beware of glossy laminates which could cause theenamel to separate, sag, or provide poor adhesion.

B. While still wet, the POLYCOR®

enamel can beflecked or cobwebbed.

C. When using laminates that contain a ‘waxsurface’ or ‘mold release,’ remove this surfacebefore coating with POLYCOR

®enamel. Sand with

rough sandpaper to remove all indications of wax ormold release. Then wipe with solvent.

In all cases, before applying POLYCOR®

enamels to anysurface, be sure the surface is clean, dry, and free fromasphalt, dirt, dust, grease, oil, form oil, soap or cleaningagents, disinfectants, and deodorants.

3. APPLICATION—Enamels should NOT be applied tosurfaces when the temperature is below 70ºF (21ºC);inadequate cure can result.

Normally, enamels are applied with spray equipment, butthey can be rolled. Brushing is not recommended due topoor flow and leveling. Refer to Part Four, Chapter III.4on Application for additional specific recommendations.Equipment, settings, and techniques for spraying gelcoats are the same for enamels.

CCP recommends a delivery rate of no more than 2.5pounds per minute with conventional air-atomizedequipment, and no more than four pounds per minutewith airless equipment.

For optimum results, uniform catalyst mix must beachieved. Even with the equipment properly calibrated,problems can occur due to: poorly atomized catalyst;surging problems (gel coat or catalyst); poor tipalignment (catalyst to gel coat mix); contamination; orpoor application procedures. Any of these conditions willquickly negate all benefits of calibration. The equipment(and application procedures) must be monitored on aroutine basis to ensure proper application and cure ofthe gel coat. Inquire about and adhere to all equipmentmanufacturers’ recommendations.

Equipment, pot pressure, temperature, and length of



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OPEN MOLDING: Specialty Gel Coats—EnamelsCopyright 2008

APPLICATION continued:

hoses will vary the spraying; therefore, it is necessary toadjust equipment to obtain a good surface.One gallon ofPOLYCOR

®enamel will cover approximately 60 to 80

square feet, depending on the film thickness of thecoating. A wet film thickness of 18 ± 2 mils isrecommended for proper hiding, cure, and performanceproperties. A film below 12 mils may not cure properly.Excessive millages above 24 may prerelease, are moreprone to cracking, and tend to trap porosity. If a ‘fleckcoat’ of POLYCOR

®enamel is desired over the base

coat of enamel, it should be applied while the base coatis wet.

CAUTION: Enamels are not compatible in the liquidstate with gel coats or resins. Equipment must becompletely clean of these gel coats or resins beforeenamels can be used.

Do not overmix enamels. Overmixing breaks downviscosity, increasing tendencies to sag, and causesstyrene loss, which could contribute to porosity. Enamelshould be mixed once a day for 10 minutes. The enamelshould be mixed to the sides and bottom of the containerwith the least amount of turbulence possible. Airbubbling should not be used for mixing. It is not effective,and only serves as a potential for water or oilcontamination.

Do not add any material, other than a recommendedmethyl ethyl ketone peroxide, to these products withoutthe advice of a representative of the Cook Compositesand Polymers Company.

4. CURE—It is recommended that gel time be checkedin the customer’s plant because age, temperature,humidity and catalyst will produce varied gel times. Referto CCP Product Data Sheets for specific catalystrecommendations.

The catalyst level should not exceed 3 percent or fallbelow 1.2 percent for proper cure. Recommended rangeis 1.2 percent to 3 percent, with 1.8 percent at 77ºF(25ºC) being ideal. Cure characteristics are dependenton material temperature, room temperature, humidity, airmovement, and catalyst concentration. Special fast-cureversions are available but must be requested. Theseproducts offer layup times of 30 minutes or less,depending on gel times. Fast-cure products have shorterstability and should not be inventoried over 45 days.

These products (standard or fast cure) should not beused when temperature conditions are below 70ºF(21ºC), as curing may be adversely affected.

5. AVAILABILITY—POLYCOR®

enamels are availablein clear, white, or any of the colors listed in the standardgel coat color deck.

Special colors are available upon request. Economyenamels also are available.

6. CLEANUP—Clean all equipment uponcompletion of the application, as it will be impossible toclean equipment if the POLYCOR

®enamel sets up and

is allowed to cure in the hoses and gun.



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OPEN MOLDING: Specialty Gel Coats—EnamelsCopyright 2008



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Page 4 of 4

OPEN MOLDING: Vinyl Ester Barrier Coats

Composites

Applications Guide

Part Four, Chapter IV

Copyright 2008

In This Chapter

1. Introduction

2. Materials

3. Application

4. Performance

1. INTRODUCTION—Vinyl ester (VE) barrier coats arespecialized gel coat formulations designed to enhancethe performance of composite laminates. Barrier coatsare primarily used in the marine industry, but can beused in any application where improved osmotic blisterresistance and part cosmetics are desired. Use of barriercoats can also reduce production cycle times in someapplications.

2. MATERIALS—Barrier coats are formulated from thesame types of materials as used in gel coats. (See PartFour, Chapter II.1) However, barrier coats are generallyformulated with vinyl ester polymers. Other polymertypes, such as isophthalic polyesters and isophthalicpolyester/polyurethane hybrids, have been used inbarrier coat formulations, but their usage is limited.Another difference between barrier coats and gel coatsis that barrier coats are not formulated for use as anexterior coating. Barrier coats rapidly chalk and fadewhen used in this application.

3. APPLICATION—A barrier coat is applied directlybehind the gel coat prior to application of the structurallaminate. Application of vinyl ester barrier coats is similarto that of gel coats. Vinyl ester barrier coats should bemixed prior to application to ensure homogeneity of thematerial and to break down the viscosity in preparationfor spraying. MACT compliant barrier coats are generallyhigh in viscosity and should be at least 75ºF (24ºC)when sprayed. In colder shops, in-line heaters may benecessary to raise the temperature of the material.Larger angle tips and larger diameter hoses may be

required.

Vinyl ester barrier coats can be applied throughconventional and low-emission spray equipment. Thepreferred method of spray application is eitherconventional or air-atomized, air-assisted airless, orairless. See Part Four, Chapter II.3 for additionalinformation on spray equipment and Chapter III.4 foradditional application information. Always refer to theproduct data sheet for specific application information.

The vinyl ester barrier coat must be applied correctly torealize the performance benefits. In particular, thethickness of the vinyl ester barrier coat is critical. Thinapplication will result in undercure, causing poorcosmetics and osmotic blister resistance. Thickapplication can lead to increased cracking.

4. PERFORMANCE—Composite parts fabricated witha correctly applied barrier coat will have significantlyreduced blistering in comparison to parts fabricatedwithout a barrier coat. The pictures below show thecomparison of laminates that have been exposed toboiling water for a minimum of 100 hours. Each laminatewas fabricated with two gel coat thicknesses.

Reduction of osmotic blistering is accomplished by twomechanisms. First, the vinyl ester polymers used toformulate the barrier coat inherently have low water-absorption properties. Second, use of a barrier coatmoves laminate porosity or air voids away from the gelcoat. Laminate porosity at the gel coat-laminate interfaceis a source of blistering and cosmetic defects.

Vinyl ester barrier coats also improve laminatecosmetics by reducing fiber print-through and distortion.

Use of a barrier coat increases the distance of thelaminate’s reinforcing fibers, balsa, and other structuralparts from the gel-coated surface, reducing the impact ofthese features on laminate cosmetics. Vinyl ester barriercoats also provide protection against dimensionalchanges (shrinkage) of the laminating resin during post-demold curing. Vinyl ester barrier coats are two to threetimes tougher than typical pigmented gel coats, so the



Page 1 of 4


Composites

Applications Guide

Laminates After 100 Hours Boiling Water Exposure

Thick Gel Coat

Thin Gel Coat

Laminate with VE Barrier Boat

( No blisters)

Laminate without VE Barrier Coat

(Heavily blistered)

PERFORMANCE continued:

increased thickness can be added without increasing therisk of cracking that is associated with thick gel coatapplications.

In addition to the performance benefits, fabricators havefound that the use of a vinyl ester barrier coataccelerates the production cycle compared to laminatesfabricated using a conventional skin coat. To realize the

cosmetic benefits of a skin coat, it must be allowed tocure thoroughly prior to laminate application. However, avinyl ester barrier coat needs only to cure to a tack-freecondition prior to proceeding with lamination. The barriercoat reaches a tack-free condition much more quicklythan the skin coat achieves a thorough cure. This cycletime savings is illustrated below for a high volume boatmanufacturing operation.



Page 2 of 4


Copyright 2008



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Page 4 of 4

OPEN MOLDING: Lamination—Laminating Resins


Part Four, Chapter V.1

Copyright 2008


2. Laminating Resin Formulation

3. Laminating Resin Specifications

1. INTRODUCTION—Laminating resins are polyesteror vinyl ester resins that are formulated for use in openmold, spray-up or hand lay-up processes at ambient orroom temperatures. These are the most versatile of thecomposite resins and can be used to manufacture awide variety of finished product from boats to bathtubs.Laminating resins can be formulated for use in the neatform or filled with mineral fillers.

2. LAMINATING RESIN FORMULATION—Laminatingresins are formulated from several components,including the polymer, reactive monomer, thixotropicagents, promoters, inhibitors, and specialty additives.The specific components and amounts used are dictatedby the end-user’s processing requirements,requirements for finished part performance, and costconsiderations. Emissions regulations also affect theresin formulation. Processing requirements typicallyinclude sprayability, wetout, sag, working time, trim time,cure or Barcol development time, and peak exothermtemperature. Finished part performance requirementscan include part appearance, physical properties, waterresistance, weathering resistance, corrosion resistance,bond strength, and flame retardancy among others.

A. Polymer—The polymer type and grade oflaminating resin help define the finished propertiesof the composites as well as the processing andapplication characteristics. The polymer grade is thefirst consideration when selecting a laminating resin.Besides the mechanical strength and processingproperties for each grade of resin there are also costdifferences between the various grades.

Historically, orthophthalic- and isophthalic-basedresin chemistries were the dominate grades used forlaminating resins. Both provide high mechanical

strength and good secondary bonding. Theisophthalic-based resins have slightly higher tensileproperties and provide better chemical, heat, andmoisture resistance than the orthophtalic resins.Both orthophthalic and isophthalic resins have beendisplaced in some applications by Dicyclopentadiene(DCPD) resins.

Three factors have contributed to the increasing useof DCPD grade resins in open molding productsover the last 15 to 20 years. The first is the demandfor improved surface smoothness on finished partsin consumer markets. Resins based on DCPDprovide smooth finished surfaces with less print-through and distortion. The second factor is theincreasingly restrictive regulatory rules on emissionof styrene. DCPD polymers can be formulated intousable laminating resins at much lower styrenelevels. Typical styrene contents of an isophthalic-based resin is 45 to 50%, whereas the levels inDCPD laminating resins can be under 30%. Thefinal reason for DCPD resins displacement oforthophthalic and isophthalic is cost. DCPD-basedlaminating resins historically have been more cost-effective than other resins while providing laminateswith lower void content, less fiber-print, andcompliance to environmental regulations.

Most laminating resins are a blend of DCPD andother resins. These other resin chemistries includeorthophthalic, isophthalic, and vinyl ester type resinsthat modify the final blend in some way. Resinsmade with 100% DCPD polymer have lower tensileproperties and provide short windows for secondarybonding. The use of blending resins impart some ofthat resin’s characteristics to the final blend. (SeePart Three, Chapter II on General Chemistry of FRPComposites Resins for more information.)

All polyester polymers have an unsaturated acidcomponent, typically maleic anhydride. Theunsaturation in the polymer provides a site forreaction with the monomer also known as cross-linking.



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OPEN MOLDING: Lamination—Laminating ResinsCopyright 2008

B. Monomer—The monomer fulfills two roles in thelaminating resin. First, it is chemically reactive andcross-links with the reactive sites in the polymer toform the rigid thermoset material. All polymers usedfor laminating have an unsaturated acid component,typically maleic anhydride. This unsaturation in thepolymer provides a site for reaction with themonomer, also known as cross-linking. The secondpurpose for monomers is to reduce the viscosity ofthe polymer to workable levels for the laminatingapplication. Without the addition of a diluent,unsaturated polyesters polymers in laminating resinsare solid or very highly viscous materials at ambienttemperatures. Therefore, laminating resins areactually solutions of polymers in a reactive diluentmonomer. Some common monomers used inlaminating resins are styrene, vinyl toluene, methylmethacrylate (MMA), and alpha methyl styrene. Theamount and combination of these monomers affectthe glass fiber wetout , exotherm temperaturereached during curing, cure rate, and mechanical,thermal, and electrical properties of the finallaminate. Emissions regulations limit the type and/oramount of monomers that can be used in thelaminating resin.

C. Thixotropic Agents—Laminating resins areformulated to be thixotropic or have a viscosity thatis dependent on shear rate. A laminating resinshould have a low viscosity during high shearoperations such as pumping, spraying, and wetout.After these high shear operations are completed, theresin should recover to a high viscosity to preventsag and/or draining. This thixotropic behavior isobtained through use of thixotropic agents (fumedsilica, Aerosil

®from Degussa, Cabosil

®from Cabot).

These materials form a network with the polymerthrough hydrogen bonding. During high shear, thisnetwork breaks down and lowers the viscosity of thematerial. After the high shear is completed, thenetwork reforms or recovers and the viscosity of theresin increases. The faster the rate of recovery thelower the risk of sag or drainage.

The thixotropy of a resin is determined by measuringthe low shear and high shear viscosity of the resin.The ratio of these two values is reported as theThixotropic Index (TI). For unfilled laminating resins,the high shear viscosity generally ranges from 400

to 700 cps. TIs are typically 2 to 4. Filled laminatingresins typically have lower TIs. In filled systems, thethixotropy not only helps prevent sag and drainingbut helps to hold fillers in suspension.

D. Promoters and Inhibitors—The types andlevels of promoters and inhibitors used in laminatingresins control the cure rate and, to some degree, thefinal properties of the composite. Most laminatingresins are cured under ambient conditions (65 to95°F [18 to 35°F]) with peroxide catalysts. Curing orcross-linking of a typical laminating resin includesthe following:

• Gel time, or the working time before theresin solidifies

• Peak exotherm temperature, or heat of thereaction

• Hardness development rate measured by aBarcol impressor, which determines when apart can be trimmed and demolded

• Final Cure when most of the compositesproperties are developed

Promoters act to increase the reaction rate of thecure. Promoters, also called accelerators, split theperoxide catalyst into free radicals. These freeradicals attack the unsaturation sites in the polymer,preparing them for reaction with the monomer. Themost common promoters used in laminating resinsare salts of cobalt metal, such as cobalt octoate andcobalt napthenate. However, cobalt salts bythemselves do not typically drive the cure tocompletion. Other materials called co-promoters areused to modify the cure behavior and increase thedegree of cure. Co-promoters enhance the ability ofpromoters to split the peroxide catalyst into freeradicals. They are very effective in shortening thegel time and accelerating the cure or hardnessdevelopment rate. Typical co-promoters are aminessuch as dimethyl aniline (DMA) or diethyl aniline(DEA).

Promoters and inhibitors can also affect the color ofthe cured resin. This effect must be consideredwhen formulating low-color or pigmented systems.

Low peak exotherm temperatures can be a sign ofundercure. High peak exotherm temperatures canresult in mold damage.



Page 2 of 6


Promoters and Inhibitors continued:

Inhibitors have a converse or opposite effect thanpromoters on the cure of a laminating resin.Inhibitors lengthen the gel time, modify the cure, andstabilize the shelf life. Inhibitors used in laminatingresins are effective at relatively low concentrations.The addition of 20-30 parts per million of certaininhibitors will double gel times in some laminatingresins. There are a variety of compounds that canbe used to inhibit cure. Because of the low levels ofinhibitors needed to affect cure, precautions shouldbe taken to avoid contamination from potentialsources of inhibiting compounds. These includewater, phenolic compounds, copper, and evenentrapped oxygen for air. Oxygen is a stronginhibitor and is the reason that the backside air-exposed surfaces in open molding remain tackyeven after the laminate is cured. Surfacing agentscan be added to resins to seal the air-exposed sideto achieve a tack-free backside.

E. Speciality Additives—In addition to the abovematerials, a number of other additives can be usedin laminating resin formulations to affect properties.These include processing aids such as air releaseagents, wetting agents, color change dyes to showcatalyst addition, and odorants. Additives can alsobe used to affect final part performance, such aspigments and dyes, UV absorbers and lightstabilizers for weathering performance and a varietyof additives to impart flame-retardant properties.

3. LAMINATING RESIN SPECIFICATIONS—Whenselecting a resin for an application there are severalspecifications to consider based on the method ofapplication, the part dimensions, and the rate ofproduction.

When producing laminating resins, resin manufacturersrun a variety of quality control tests to ensure that theproduct being produced will meet the needs of endusers. Final results of these tests are reported to the enduser via the Certificate of Analysis (COA). Typical testresults reported on a COA include:

• Brookfield®

viscosity• Thixotropic Index (TI)• 100 gram mass cup gel time, time to peak

exotherm and peak exotherm• Laminate gel time and peak exotherm• Laminate Barcol development

See Part Ten, Chapter I, Appendix A on Quality ControlLab and Test Methods for information on the equipmentand procedures used to run these tests.

The 100 gram mass cup gel properties are a standard inthe FRP industry for characterizing resin cure. Theseparameters are valuable to the resin manufacturer whenproducing the product, and to end users for verifying thatthe product will be suitable for use in their process.However, it is important to the fabricator to understandthat 100 gram mass cup gel parameters will notnecessarily correspond to those observed in the actualapplication. For example, the 100 gram mass cup geltime is generally faster than the gel time in a laminate,and the 100 gram mass cup peak exotherm is muchhigher than that of the laminate.



Page 3 of 6


Large Part,Slow Production,Multiple PassLaminate, <125mils

Large Part,Fast Production,Thick Laminate,Single StageLaminate,>180mils

Small Part,Slow Production,Thin Laminate,Single Stage,<125 mils

Small Part,Fast Production,Single Stage orMultiple Pass,125-180 mils

Viscosity, cps(Brookfield )

550-650 550-650 450-550 350-450

Thixotropic Index (TI) 3.5 3.5 >2.0 >2.0

Gel Time, Minutes 35-45 35-40 20-30 15-20

Gel-to-Peak, Minutes 10-12 12-14 7-9 10-12

Peak Exotherm, 100g,°F

320-340 280-300 320-340 310-320



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Page 6 of 6

OPEN MOLDING: Lamination—Fiber Reinforcements


Part Four, Chapter V.2Copyright 2008

In This Chapter1. Fiber Reinforcement

2. Laminate Thickness vs. Layers of Glass

Reinforcement

1. FIBER REINFORCEMENT—The lamination processuses a variety of reinforcements. The typicalreinforcement is fiberglass. Fiberglass is the “F” in theFRP (Fiberglass Reinforced Plastic) acronym. Othertypes of reinforcements include fillers or flake glass andare used where specific properties are needed.

Various types of fiberglass grades are available. E-glassis the most widely used grade. E-glass, first developedfor its good electrical properties (low conductivity), alsoprovides good mechanical properties, and somemeasure of corrosion and water resistance. This is thegeneral-purpose grade of glass used in most openmolding applications. C-glass, or Chemical glass, wasdeveloped specifically to improve resistance to chemicalattack from acids. ECR-glass is another grade of glassthat was developed to provide improved chemicalresistance as well as higher mechanical properties thanE-glass.

Fiberglass filaments are brittle if left untreated.Fiberglass manufacturers add a formulated protectivecoating around each individual filament. The coating isknown as a sizing. The sizing acts to protect the dryglass during subsequent processes, such as weaving orknitting. It also includes chemistries to improve the bondstrength between the resin and the glass filament.Different composite resins require specific sizingchemistries. Thermoplastics, such as polypropylene andPET, require different sizing chemistries than typicalunsaturated polyester and vinyl ester resins used inopen molded FRP. Indications of mismatched sizingchemistry in FRP include poor fiber wetout, “jackstrawing,” or fiber burn and low laminate mechanicalproperties.

Reinforcement is not limited to fiberglass. Syntheticpolymers in roving, mat, or entangled sheet form areavailable. Reinforcements can also be made frominorganic elements or compounds such as boron, carbon(graphite), minerals, or silica. This discussion willprimarily refer to fiberglass because it is the mostcommon reinforcement.

A. Surfacing Mat (Veil)—Veil is a thin (usually 10mils [0.01 inches]) layer of fine, soft fiberglass orsynthetic fiber that is used next to the gel coat. It isused to reduce the transfer of fiber pattern throughthe gel coat from the coarser glass mats. It is alsoused in corrosion work as the last layer next toexposed surfaces, where it yields a resin-richsurface.

B. Chopped Strand Mat—Chopped strand mat(CSM) is delivered in rolls in widths of up to 120inches. CSM is available in weights from 3/4 to 3ounces per square foot. Structurally, CSM hasmultidirectional strength because of the randomorientation of the fibers. CSM is used toinexpensively build up bulk and to increase strengthand stiffness. It is made up of chopped strands ofroving up to 2 inches long. These strands are heldtogether with a binder, which is soluble in thepolyester resin. Excess binder can cause a dimplingof the gel coat surface. New CSM lots should beinspected for particles (small and crystalline).Normally, there is more binder on one side of themat than the other. Some mats are made with aninsoluble binder and cannot be used in the hand lay-up process. Make certain that the CSM is rated foruse with polyester and vinyl ester resins.

C. Roving—Roving is a loose twine of glass fibers(usually 60) wound up into a cylindrical packageweighing about 35 pounds. It is the least costly formof fiberglass. It is used mostly in the spray-upprocess, where it is chopped and fed withconverging streams of catalyzed resin onto the moldsurface. Sometimes the continuous roving is used



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OPEN MOLDING: Lamination—Fiber ReinforcementsCopyright 2008

Roving continued:as a wrap-around (for circumferential strength) inspecial configurations such as tanks, pipes, andstiffening ribs. Roving is available with one redstrand (out of 60) called a tracer to help gauge theuniformity of thickness and distribution. The glassfibers become transparent when wet with resin.

The ideal roving for use in spray-up has goodcompatibility with the resin, good cuttingcharacteristics, easy rollout, fast wetout, low watersensitivity, and minimal build-up of static electricity.Handling properties vary, notably to the extent thatthe sizing on the roving renders it ‘hard’ or ‘soft.’Hard rovings cut well and have good strand integrity.Soft rovings tend to fray or open up when cut;however, they can be compacted into sharp corners,such as the strakes of boat hulls, without springback.

D. Woven Roving (WR) —This material costsabout the same as or a little less than mat, but istwice as strong in tensile and flexural strength, somost structural laminates have some woven rovingin their makeup. It is a coarse weave and isavailable in weights from 13 to 27 ounces persquare yard; 18 and 24 ounces are most common.The loose weave of WR conforms to contours betterthan mat or cloth. However, its coarse weave issometimes problematic since the pockets formed bythe warp and weft of the weave allow for localizedresin-rich areas in the laminate. These pockets ofresin shrink more on curing that the higher glasscontent rovings. This outline can be ‘telegraphed’through the gel coat, leaving a checkerboard look tothe finished side of the laminate. It is best whenusing woven roving to have at least 90 to 100 mils ofmat or chopped roving between the woven rovingand gel coat to minimize the print-through. In mostapplications, alternating woven products with CSM isrecommended to improve interlaminar shear and tobetter transfer any loading between the plies.Combo mats consisting of woven roving with achopped strand mat adhered with a binder to oneside are widely used as a way to ensure goodbonding between plies of woven roving.

E. Engineered Fabrics—These fabrics align thereinforcements in a particular direction or bias. Thisgives laminate designers the ability to reinforce the

composite for various loadings with less weight orthickness. Typical examples of engineered fabricsare stitched mats. These come in a variety ofmultiaxial fabrics, including Unidirectional, Biaxial,Tri Axial, and Quad Axial. These fabrics can useother fibers, such as carbon or aramid along withglass fibers, to provide specific properties needed.Among some of the most unique engineered fabricsare those with a three-dimensional architecture.These fabrics not only have directional fiberplacement in the X and Y coordinates but also a Zaxis component. Fibers can be oriented in a varietyof ways. Both the fabrication order and the type offabrics used in a laminate design can affect the finalcomposite properties. The selection of whichengineered fabric to use should be based on theoverall design and sample laminates tested underthe usage conditions and loadings.

F. Cloth (Hand Lay-up and Spray-up)—Cloth is themost expensive form of fiberglass and the strongestwoven material on an equivalent weight basis. It isavailable in weights from 2 to 40 ounces per squareyard. Although most production parts utilize 4 to 10ounce material, the heavier weights, such as 40ounce cloth, can be used in tooling to build upstrength and thickness quickly. It is available indifferent types of weaves, such as twill, crowfoot,and satin style; where the satin is stronger andconforms more easily to compound curves. Cloth isused principally as a finishing layer for betterappearance or a skin layer (just behind the gel coat)for extra strength. It will ‘telegraph’ through the gelcoat as does the woven roving, but with less ‘profile.’

G. Core Materials—When the fabricator needs tobuild in stiffness and strength without significantincreases in weight, core materials are sandwichedbetween layers of fiberglass. These core materialsmay be metal or paper honeycomb, cardboard,wood, foam, composites of hollow bubbles andfiberglass, or combinations thereof. Core materialcan also be in sprayable form. Consideration mustbe given to the resin demand of core materials andtheir impact on cure and on subsequentprint/distortion. Their placement in order ofconstruction must also be studied for optimumresults. The angles, ribs, and tie-ins created during



Page 2 of 7


Core Materials continued:sandwiching add sturdiness, stiffness, strength andbulk to the FRP structure. Reinforcement is usuallyspecified by the type of material, number of ouncesper unit area, and location in the laminate. The firstlayer is important in that it must reinforce the gelcoat and be free of air pockets. Reinforcing is bestensured by a thin layer (skin coat) of binder-freeglass.

Studies have shown that laminate construction hasan important effect on the performance of the gelcoat. To reduce cracking, blisters, and crazing in gelcoats, best results are obtained by using a thin coatof chopped glass and resin behind the gel coat;then, continuing with 1 1/2 ounces glass mat lay-up.Proper roll out of the skin coat is important toremove all air voids at the gel coat surface.

The next layer or two should be a heavier mat (1 1/2ounces), or chopped roving depending on theultimate thickness desired. This provides for fastlaminate build-up. Another advantage of starting thelaminate with mat layers is that it positions the fabriclayers, which show a greater fiber pattern, fartherfrom the surface.

The third or fourth layer, if it is the final layer, can bewoven roving or cloth. Woven roving should be usedwhere strength is critical. Otherwise, 6 or 10 ouncecloth is used for a better finished surface (than themat) and a little extra strength. Another advantage ofcloth as a final layer is that the laminator cansqueegee hard on the surface to remove trapped air

bubbles and excess resin. For best strength,succeeding layers should be alternating mat andwoven roving (24 ounce standard). It is not usuallygood practice to face two woven layers because ofpoorer inter-laminate bond and a higher chance forporosity (air bubbles entrapped in the cloth or wovenroving, usually extending the entire thickness of thefabric).

Nine total ounces of mat per square foot will result ina 1/4 inch laminate (at 30 percent glass content).Glass content is usually specified to prevent resin-rich areas (too low glass content) which would crackand craze, or resin-starved areas (too high glasscontent) which would cause porosity. An all-mat orchop laminate should have a tolerance of 30 percentglass (low) to 35 percent glass (maximum) for bestresults. When woven roving is used inconjunctionwith mat, the range of glass content canbe as high as 80 percent for the ultimate in strength.Bag molded parts should have a glass content of 60to 65 percent.

2. LAMINATE THICKNESS VERSUS LAYERS OFGLASS REINFORCEMENT—The following tableisoffered as an aid toward estimating approximatelaminate thickness of various glass reinforcing materialsand typical laminating resins. The values given areaverages and will vary according to applicationtechnique.



Page 3 of 7


REINFORCEMENT TYPE NUMBER OF LAYERS LAMINATE

THICKNESS

(inches)

PERCENT GLASS CONTENT

(%)

1.5 oz. Chopped Strand Mat

(CSM)1

1

1

0.035-0.040

0.025-0.300

37

45

2 oz. Chopped Strand Mat

(CSM)

1

1

0.045-0.055

0.040-0.050

37

45

1808 Combo Biaxal Stitch/CSM

Mat

1

2

3

0.070-0.075

0.140-0.150

0.215-0.225

37

37

37

18 oz. WOVEN ROVING (WR) 1

2

3

0.030-0.350

0.065-0.070

0.100-0.105

45

45

45

24 oz. WOVEN ROVING (WR)2

1

2

3

0.035-0.040

0.075-0.080

0.115-0.110

50

50

50

Alternating layers of 1.5 oz.

Chopped Strand Mat (CSM) and

18 oz. Woven Roving

3 (CSM/WR/CSM)

5

(CSM/WR/CSM/WR/CS

M)

7

(CSM/WR/CSM/WR/CS

M/WR/CSM)

0.130-0.135

0.215-0.220

0.300-0.305

WR @ 45, CSM @26

WR @ 45, CSM @26

WR @ 45, CSM @26

Alternating layers of 1.5 oz.

Chopped Strand Mat (CSM) and

24 oz. Woven Roving (WR)

3 (CSM/ WR/ CSM)

5

(CSM/WR/CSM/WR/CS

M)

7

(CSM/WR/CSM/WR/CS

M/WR/CSM)

0.145 -0.0150

0.235-0.240

0.330-0.335

WR @ 45 CSM @26

WR @ 45, CSM @26

WR @ 45, CSM @26



Page 4 of 7


DRY GLASS THICKNESS

11.5 oz. mat 0.022 inch

224 oz. woven roving 0.024 inch



Page 5 of 7




Page 6 of 7







Page 7 of 7

OPEN MOLDING: Lamination—Initiators



In This Chapter1. Function and Types

2. Usage Levels

1. FUNCTION AND TYPES—The function of a catalyst

or initiator is to start the chemical reaction that cures or

cross-links the resin. The most common type of catalyst

used in open mold, ambient temperature lamination is

called organic peroxide. For more general information on

peroxide catalysts, refer to Part Three, Chapter II, on

General Chemistry of FRP Composites Resins.

Laminators can choose from many types of organic

peroxide catalysts. Each one affects the gel and cure

behavior of the resin differently.

A. Methyl ethyl ketone peroxide (MEKP) catalysts

are the most commonly used catalysts for ambient

temperature, open mold lamination. These catalysts

are actually solutions of various MEKP isomers and

hydrogen peroxide in plasticizers. The plasticizer,

also known as a phlegmatizer, serves to stabilize the

peroxides. The same resin catalyzed with different

MEKP catalysts may show significantly different gel

and cure behavior due to differences in overall

peroxide levels and peroxide combinations. The

recommended MEKP catalyst usage level is

between 0.75 and 2.5 percent based on weight.

B. Cumene hydroperoxide (CHP)/MEKP blends

are specialized catalysts that should be considered

by laminators needing to reduce laminate peak

exotherm temperatures in comparison to those

obtained when using MEKP catalysts. Like MEKP

catalysts, CHP/MEKP blends are solutions of

peroxides (CHP, various MEKP isomers and

hydrogen peroxide) in plasticizers. The overall

peroxide content and the levels of the each of the

various peroxides will affect the catalyst

performance. In general, CHP/MEKP-blended

catalysts result in longer gel times, longer cure

times, lower peak exotherm temperatures, and

slower initial Barcol hardness development. When

used appropriately, the ultimate cure of laminates

produced with CHP/MEKP blended catalysts is

equivalent to or better than those produced with

MEKP catalysts. CHP/MEKP-blended catalysts are

not recommended for thin laminates or skin coats

since reduced exotherm temperatures may not allow

for complete cure. Use of MEKP/CHP catalyst

blends in cooler temperatures should be carefully

reviewed by the laminator and used only when

required due to excessive peak exotherm

temperatures. Recommended usage levels of

CHP/MEKP-blended catalysts are typically higher

than for MEKP catalysts, 1.5 to 2.75 percent by

weight.

C. Acetyl acetone peroxide (AAP) or 2,4

Pentadione catalyst is another specialized catalyst

that should be considered by laminators needing

faster cure and demold times at similar gel times

obtained with MEKP catalysts. AAP catalysts are

solutions of 2, 4 Pentadione peroxides in

plasticizers. Use of AAP catalysts is somewhat

limited since the faster cure rate also results in

higher peak exotherm temperatures. The faster cure

rate also results in a narrower trim window.

Recommended usage levels of AAP catalysts are

similar to MEKP catalysts, 0.75 to 2.25 percent.

Many catalysts are available with a red dye. These red

catalysts can be used in applications that are not

sensitive to color to provide a visual indication of catalyst

level and dispersion.



Page 1 of 4

OPEN MOLDING: Lamination—InitiatorsCopyright 2008

2. USAGE LEVELS—The recommended usage levels

for catalysts are generally expressed as a range. The

starting point for catalyst usage level is typically the level

used by the resin manufacturer during quality control

testing. Resin suppliers produce resins to meet gel and

cure behavior specifications agreed to by the customer.

An important part of these specifications is the catalyst

type and level to be used during quality control testing as

well as the test temperature. Unless directed otherwise

by the customer, resin suppliers typically perform quality

control tests using 1.25 to 1.5 percent by weight MEKP

catalyst. The test temperature is typically 77ºF (25ºC).

Deviations from this usage level occur based on shop

conditions and part geometry:

A. Shop Conditions—The most important shop

condition factor affecting catalyst level is

temperature. The higher the ambient temperature,

the faster the gel and cure of the resin will occur. In

warmer conditions, it may be necessary to reduce

the catalyst level to allow appropriate working time

for the lamination operator. In cooler conditions, it

may be necessary to increase the catalyst level to

maintain desired production line speeds.

B. Part Geometry—The most important part

geometry factor affecting catalyst level is thickness.

When using the same resin and catalyst to fabricate

parts having a variety of thicknesses, the laminator

may need to adjust the catalyst level. Higher catalyst

levels may be required in thinner parts to ensure

complete cure. Lower catalyst levels may be

required in thicker parts to limit the exotherm

temperature.

When selecting a catalyst and determining a usage

level, it is highly recommended that the laminator

discuss options with their resin and catalyst suppliers.



Page 2 of 4

OPEN MOLDING: Lamination—InitiatorsCopyright 2008



Page 3 of 4







Page 4 of 4

OPEN MOLDING: Lamination—Equipment and Application Methods




2. Process Overview

3. Equipment

4. Equipment Calibration

5. Key Factors Affecting Quality

6. Lamination Methods

7. Equipment, Tools, and Supplies

1. INTRODUCTION—Lamination is the process ofcombining resin and reinforcing materials on an openmold. Use of proper lamination equipment andtechniques is critical to producing structurally soundparts that meet design requirements as well as visuallyappealing parts that meet cosmetic requirements.Improperly applied laminates add cost to the part due toscrap and rework. Making the investment in properequipment, equipment maintenance and calibration, andoperator training can pay big dividends by reducingrework and scrap. This chapter provides an overview ofthe lamination process, lamination equipment,equipment calibration procedures, key factors affectinglaminate quality, and lamination methods. A list ofequipment, tools, and supplies that should be availablein the lamination shop is also provided.

2. PROCESS OVERVIEW—Lamination of glass fiberreinforcements can be accomplished by hand lay-up orspray-up methods. Hand lay-up is used when applyingroll good reinforcements such as chopped strand matsand textile constructions that are stitched or woven. Theroll good reinforcement is cut to the desired shape andmanually placed in the mold. Brushes, rollers, or sprayguns can be used to apply the resin. Spray-up is usedwhen the laminate reinforcement is chopped roving.Continuous strands of fiberglass roving are pulledthrough a chopper and cut into short lengths (1/4 to 1inch lengths are typical) called chopped roving. Choppedroving and catalyzed resin are combined and applied

onto the lamination surface with a spray gun or a flowchopper. In both hand lay-up and spray-up, the glass ismanually wet out and compacted with lamination rollers.

Selection of spray-up or hand lay-up methods for aparticular part depends on the part configuration,mechanical property requirements, thickness tolerances,and cost considerations.

• Complexity of shape often favors spray-up overhand lay-up since complex shapes require time-consuming and labor-intensive trimming andtailoring of roll goods plies. However, small anddeep drafted parts cannot generally be producedby spray-up for economic reasons.

• Hand lay-up laminates can be significantlystronger than spray-up laminates due to higherglass contents possible with some roll goods.

• Laminate thickness is more easily controlledwith hand lay-up than spray-up. In hand lay-upthe laminate thickness is based on the type ofroll goods used, the areal weight of the rollgoods, and the number of layers of roll goods. Inspray-up, the laminate thickness is dependenton the operator’s skill in evenly depositing therequired amount of resin and glass over partsurface.

• The spray-up process is generally the lower costprocess when compared to hand lay-up. Rovingis generally less expensive than roll goods. Also,waste from overspray will typically be less thanwaste from trimming roll goods, particularlywhen an experienced spray operator is used.Labor costs are also generally lower for spray-up since no trimming or tailoring of roll goodsplies is required. Also, resin and reinforcementcan be deposited faster with spray-up than handlay-up, particularly on contoured surfaces.Spray-up or chopped parts also have theadvantage in producing a cosmetically smoothouter surface. The random fiber placement andthe lack of the binders that are in mat goodsallow for a better surface quality.



Page 1 of 11

OPEN MOLDING: Lamination—Equipment and Application MethodsCopyright 2008

PROCESS OVERVIEW continued:Hand lay-up and spray-up are often combinedwithin the same part or laminate to realize theadvantages of both processes.

3. EQUIPMENT—Numerous types of laminationequipment are available to FRP fabricators. Theequipment can be as simple as a paintbrush or ascomplex as a robotic unit programmed to select, meter,mix, and apply the reinforcements and resin. Several keyfeatures can categorize lamination equipment: catalystmetering and incorporation method, resin applicationmethod, and glass application method.

A. Catalyst Metering and Incorporation—Slavearm systems have become the industry standard forcatalyst metering. The advantage of slave armsystems over other catalyst metering systems is thatcatalyst flow rate is tied to the resin flow rate. Thishelps to ensure consistent catalyzation at thedesired level. The catalyzation of the resin is criticalfor production speed, part cosmetics, and the finalproperties of the part. In slave arm systems, the airmotor for the resin is used to pump the catalyst, thusthe resin and catalyst are connected to the same airmotor (hence, slaved together). To prevent excesspressure being put on the catalyst, a pressure reliefvalve is incorporated. The slave pump may be seteither by specific intervals or on a dial-adjustedscale, generally ranging from 0.5 to 4 percent.Incorporation or mixing of the catalyst with the resincan either be accomplished internally or externally,depending on the specific type of equipment beingused.

Other types of catalyst metering and incorporationsystems include catalyst injection and split batch ordual nozzle spray gun system. In catalyst injectionsystems, a small pressure vessel with a flow meteris used to inject a metered quantity of catalyst intothe resin stream. The catalyst is then mixed withresin either internally or externally. In catalystinjection systems, the control of the catalyst contentis dictated by multiple variables including resin flowrate and air pressure to the catalyst pot.

Split batch or dual nozzle spray gun systems utilizetwo streams of resin. One stream is unpromoted butcontains enough catalyst to cure both streams. Theother stream is promoted but uncatalyzed. The twostreams of resin are delivered to the spray gun so

that the two streams intermix. The intermixing mayoccur internally or externally. These systems requirethe use of two separate resin systems. Thecatalyst/resin stream must be used within its pot life.

Neither catalyst injection nor split batch systems arein widespread use today.

B. Resin Application Method—Historically,atomized spray has been the most common methodof resin application particularly in spray-upoperations. However, EPA and OSHA requirementsto reduce styrene emissions has resulted in theemergence of new resin application techniques suchas non-atomized spraying and non-spray methods.

Atomized spray involves the use of high fluidpressure or compressed air (up to 100 psi) to createa finely divided or atomized spray pattern. The smallsize of the particles in the spray pattern means largeexposed surface area. Evaporation of monomersfrom this surface area creates high emissions.Catalyst incorporation can be either internal orexternal.

In non-atomized spray, the resin exits the gun inlow-pressure streams. The impingement techniqueuses two low-pressure streams that cross eachother. The collision of these streams creates a spraypattern. Flow coatingers (another technique) usesmultiple, fine diameter orifices to produce parallelstreams. Non-atomized spray results in lessexposed surface area than atomized spray, andtherefore lower emissions. Catalyst incorporationcan be either internal or external.

Flow coaters utilize internal catalyst mixing so themixing chamber must be periodically flushed with asolvent to prevent the accumulation of gelled resin.Resin distribution with flow coaters is also not aseven as with other spray techniques. This can leadto thickness and glass content variations, particularlyin thin laminates.

Pressure-fed rollers, a non-spray technique, areused for hand lay-up applications. The roller systemalso utilizes internal catalyst mixing and must beperiodically flushed with solvent. Pressure is used topush catalyzed resin out of a roller similar to atypical paint roller. Roller size and length can makeresin application by this method difficult in tightlycontoured areas.



Page 2 of 11


C. Glass Application Method—Glass fiberreinforcements can be either hand laid or sprayed.For spray-up, an air-powered roving chopper iscombined with the spray or flow coater resinapplication head. The resin application head androving chopper are suspended from a carrying boomto allow the operator freedom of movement. One ormore strands of roving are guided from spools alongthe boom to the chopper. Ceramic guides arerecommended to reduce fuzzing and static electricitygenerated by friction of the glass.

When the trigger on the chopper gun is pulled, twoopposing rollers pull the rovings into the chopper,cut the rovings to the desired lengths and propel thechopped roving toward the mold surface. Razor-likeblades mounted in one of the rollers chop the roving.Spacing of the razor blades determines the strandlength (typically one inch). Shorter strands will beeasier to roll out, but will reduce overall partstrength. Longer strands increase strength, but maynot conform to tight radii during rollout and cure.Outside the chopper, the glass fiber chop convergeswith the resin and is partially wet before reaching themold surface.

4. EQUIPMENT CALIBRATION—Calibration ofequipment is important to ensure laminate quality.Equipment should be calibrated with each use, or at thevery least daily. When calibrating spray-up equipment,the main areas of concern are resin flow rate, glass flowrate, resin-to-glass ratio, catalyst flow rate, and catalystcontent. For hand lay-up, the resin-to-glass ratio iscontrolled by the operator; however, spray guns andpressure-fed flow rollers should be calibrated for resinflow rate, catalyst flow rate, and catalyst content. Alwaysconsult the equipment manufacturer for propercalibration of a particular type of equipment.

A. Resin Flow Rate, Glass Flow Rate, andResin-to-Glass Ratio—For spray-up equipment,determine the resin and glass flow rates in poundsper minute as follows:

• Adjust the pump to the desired pressure.• Weigh two containers individually in pounds.• Direct the resin head and glass head of the

chopper gun into the separate containers.• Spray resin and glass into the containers for

10 seconds.

• Individually weigh the containers in pounds.• Determine the resin weight by subtracting

the empty weight of the resin container fromthe container weight after spraying.

• Determine the weight of glass by subtractingthe empty weight of the glass container fromthe container weight after spraying.

• Calculate the resin flow rate by multiplyingthe resin weight by 6.

• Calculate the glass flow rate by multiplyingthe glass weight by 6.

For example, if the resin weight is 2.33 pounds theresin flow rate will be 13.98 pounds per minute. Ifthe glass weight is one pound, the glass flow ratewill be 6 pounds per minute.

Total laminate output or the sum of the resin andglass flow rates can vary, but are typically between 6and 30 pounds per minute. Some of the factors toconsider when adjusting the total laminate output ofa chopper gun are:

• Part size• Available manpower for rollout• Desired laminate thickness• Gel time or working time of the resin

If the total laminate output or the resin or glass flowrates are not within the desired range, adjust theequipment per the supplier’s recommendations.

Calculate the resin content in percent by dividing theresin weight by the sum of the resin and glassweights and multiplying by 100. Calculate the glasscontent in percent by dividing the glass weight bythe sum of the resin and glass weights andmultiplying by 100. The resin-to-glass ratio is thenexpressed as resin content (percent) : to glasscontent (percent).

For example, if the resin weight is 2.33 pounds andthe glass weight is one pound, the resin content willbe 70 percent and the glass content will be 30percent. The resin-to-glass ratio is then 70:30.

If the resin-to-glass ratio is not within the part andprocess design requirements, adjust the equipmentas necessary.

For hand lay-up processes using spray guns or flowcoaters, follow the procedures above to determineresin flow rates. Resin-to-glass ratios are controlledby the operator.



Page 3 of 11


B. Catalyst Flow Rate and Catalyst Content—Determine catalyst flow rate and resin flow rate inpounds per minute as follows:

• Attach a resin/catalyst splitter (availablefrom the equipment manufacturer) to thespray equipment.

• Weigh two containers individually in pounds.• Spray the resin and catalyst streams into the

separate containers for 30 seconds.• Individually weigh the containers in pounds.• Determine the resin weight by subtracting

the empty weight of the resin container fromthe container weight after spraying.

• Determine the catalyst weight by subtractingthe empty weight of the catalyst containerfrom the container weight after spraying.

• Calculate the resin flow rate by multiplyingthe resin weight by 2.

• Calculate the catalyst flow rate bymultiplying the catalyst weight by 2.

For example, if the resin weight is 7 pounds theresin flow rate will be 14 pounds per minute. If thecatalyst weight is 0.1 pound, the catalyst flow ratewill be 0.2 pound per minute. If the resin or catalystflow rates are not within equipment supplier’srecommendations, adjust the equipment asnecessary.

Calculate the catalyst content in percent by dividingthe catalyst weight by the sum of the resin andcatalyst weights and multiplying by 100. Forexample, if the resin weight is 7 pounds and thecatalyst weight 0.1 pound, the catalyst content willbe 1.4 percent.

Catalyst content may also be checked by comparingthe gel time of resin catalyzed with a known catalystamount versus the gel time of catalyzed resin fromthe lamination equipment.

• For the control sample, obtain 100 grams ofuncatalyzed resin. Weigh the appropriateamount of catalyst into the resin. Forexample, if a catalyst content of 1.5 percentis desired, weigh 1.5 grams of catalyst intothe resin. Start a timer and thoroughly mixthe catalyst into the resin. Stop the timerwhen the resin reaches a physical gel.

• Obtain catalyzed resin from the lamination

equipment. Pour 100 grams into a container similarto the one used for the control sample. Start a timerat the time of catalyzation. Stop the timer when theresin reaches a physical gel.

The gel time of the material from the laminationequipment should be within ± 5 percent of the geltime of the control sample.

5. KEY FACTORS AFFECTING QUALITY—Keyfactors affecting laminate quality are discussed below.

A. Temperature—Temperature during laminatefabrication is the most important process variable inopen molding lamination shops. Many qualityproblems are traced to excessive temperaturevariations, and this can further be complicated byvariations in humidity and airflow. The resin andcatalyst viscosity and the resin gel and cure timesare all related to temperature. The temperature ofthe reinforcing materials, mold surface, and shopcan affect the temperature of the resin and catalystduring application. Therefore, the temperature of theresin, catalyst, reinforcing materials, mold surface,and shop should all be regulated.

Most polyester and vinyl esters are formulated foruse at temperatures between 60ºF (18ºC) and 95ºF(35ºC). Consult the product data sheet for thespecific usage temperature range for each product.

Catalysts and resins increase in viscosity withdecreasing temperature. Cold, high viscositycatalysts and resins are difficult to spray anddistribute on the mold surface. Cold, high viscosityresins are slow to wet strands of glass and otherreinforcements. Poor spray and wetting can result inincreased void content that significantly lowers themechanical properties of the laminate.

Catalysts and resins decrease in viscosity withincreasing temperature. Use of hot, low viscosityresins can result in drain-out from reinforcementsthat can increase void content and reducemechanical properties.

Resin gel time and cure rate increase withdecreasing temperature. A good rule of thumb is thatthe gel time and cure rate will double with every20ºF (10ºC) reduction in temperature and will be cutin half with every 20ºF (10ºC) increase intemperature. The slower gel times and cure times of



Page 4 of 11


KEY FACTORS AFFECTING QUALITY continued:resins in cold conditions can lead to post-cure thatcan be seen as print-through and/or distortion. Thefaster gel times and cure times in warm conditionsmay not allow enough working time for properwetout.

Within the recommended temperature usage range,the catalyst level can be varied to adjust the gel andcure time of the resin to compensate for specificshop conditions. Higher catalyst levels are used atlower temperatures, and lower catalyst levels areused at higher temperatures. Catalyst levels shouldbe maintained within a range specified by the resinmanufacturer. This range is typically between 0.75percent and 2.5 percent for most laminating resins.

Use of unsaturated polyester and particularly vinylester laminating resins at temperatures below thespecified minimum (typically 60ºF (18ºC)) can resultin permanently undercured parts. Undercured partswill have poor physical properties and cosmetics.Extremely high temperatures can also bedetrimental to the cure of laminating resins. Themonomer content may be lowered due toevaporation at elevated temperatures. In colderweather, removing parts from the temperature-controlled application area too quickly afterapplication can cause cure retardation. Even draftsof cold air should be avoided during application anduntil a sufficient degree of cure has been achieved.

To help compensate for seasonal temperaturevariances, the same resin can be supplied insummer and winter versions. Summer versions havelonger gel times to allow for more working time in hotweather. Winter versions have shorter gel times toimprove cure. Changes in viscosity can also beincorporated to provide the viscosity desired at theapplication temperature.

B. Catalyst Level—Low catalyst concentration andpoor catalyst distribution are two more leadingcauses of problems in FRP composites. Peroxidecatalysts initiate the cross-linking reactions inunsaturated polyesters or vinyl ester resins. Allperoxide-initiated resins specify a minimum catalystlevel as well as a maximum. A typical range for a 9percent active oxygen methyl ethyl ketone peroxidecatalyst is 0.75 percent to 2.5 percent. Always

consult the product datasheet for specificrecommendations on catalyst type and usage rangerecommendations.

The minimum range limit is necessary to ensure thatenough catalyst is available to achieve a suitablereaction rate and complete cure. Even smallamounts of peroxides, or other free radical sources,will start the cross linking reaction; however catalyststarved resin will be permanently under-cured andthe resulting laminate will have poor mechanicalproperties and cosmetics. Another consideration forthe minimum limit is the ability of catalyst meteringequipment to meter lower volumes. Most commercialmetering equipment also have lower volume limits.

The maximum limit is necessary due to the diluentsused in the peroxide initiator products. Thesediluents are non-reactive and high levels can‘plasticize’ the resin. ‘Plasticized’ resins have poorstiffness and hardness. This plasticizer is alsotransient in the polymer matrix and leeches out overtime and with exposure water, leaving the remaininglaminate embrittled. High catalyst levels can alsocause an increase in the monomer-to-monomer sidereactions that further weaken the laminate.

C. Catalyst Mixing—Even if an appropriatecatalyst level is specified and equipment has beenproperly calibrated, faulty equipment may fail to mixthe catalyst in the resin evenly or consistently. Partsmade with poorly mixed catalyst may not show anysymptoms during fabrication, or at demold. In fact,parts with uneven catalyst may only presentproblems after the parts are put in service. Commonindications of poorly mixed catalyst include print,distortion and delamination in laminates. Due to theseverity of these problems, proper catalystdispersion should be ensured.

D. Resin-to-Glass Ratio—The resin-to-glass ratiois the amount of resin (by weight) versus the amountof glass (by weight) in the total laminate. Theappropriate resin to glass ratio depends on the typeof glass fiber reinforcement being used. Forlaminates that are fabricated with spray-up choppedroving, the resin-to-glass ratio is typically between70:30 and 60:40. For laminates fabricated with rollgoods, the resin-to-glass ratio may be as low as40:60. Always check the data sheet for the



Page 5 of 11


Resin-to-Glass Ratio continued:reinforcement being used to determine therecommended glass content.

The resin-to-glass ratio affects the finished parts’mechanical properties, appearance, and weight.Resin-rich laminates, or laminates with high resin-to-glass ratios, have a glossy or wet appearance on theopen side of the laminate. These laminates will havelower mechanical properties than laminates withappropriate glass contents and may crack or fail inservice. Resin richness will result in additionalshrinkage that may affect the finished part’sdimensions and cosmetics due to prerelease,distortion, and fiber print. Resin richness will result inhigher laminate peak exotherms that can alsocontribute to pre-release. High peak exotherms canalso damage tooling and degrade the cosmetics ofsubsequently produced parts. Resin-rich laminatesare also heavier than laminates fabricated withproper glass contents.

Resin-poor or resin-starved laminates will have adull, dry appearance on the open side and may havesignificant porosity. In extreme cases, resin-poorlaminates will have dry fibers. These laminates willhave lower mechanical properties than laminateswith appropriate glass contents and may crack or failin service. Resin-poor laminates may also beundercured and print or distort.

E. Thickness Control—Laminate thickness controlis required to ensure a quality laminate. Thicklaminates will have higher peak exotherms duringlaminate cure than thin laminates. High exothermtemperatures can contribute to prerelease and canalso damage tooling, resulting in degradation ofcosmetics for subsequently produced parts. Duringspray-up, slow pass speeds and excessive overlapof strokes are two sources of excess laminatethickness. During hand lay-up, overlaps in roll goodscan create excess laminate thickness.

Thin laminates can also result in poor laminatequality. Thin laminates may not cure properly,resulting in poor cosmetics and mechanicalproperties. During spray-up, fast pass speeds andminimal overlap of strokes can result in thinlaminates.

F. Laminate Construction—Laminateconstruction or design has a significant impact onthe field performance of the end part. To reducecracking, blisters, and crazing, the best results areobtained by using a barrier coat behind the gel coat.(See Part Four, Open Molding, Chapter IV for moreinformation on Barrier Coats.) Skin laminates arealso used for this purpose, although they are not aseffective as barrier coat. A skin laminate is a thinlaminate applied directly behind the gel coat. Ideally,skin laminates are fabricated using chop and a high-performance laminating resin such as a vinyl ester,isophthalic polyester, or blends of these resins withDCPDs. Proper roll out of the skin coat is importantto remove all air voids at the gel coat surface. Theskin laminate must also be allowed to curethoroughly prior to subsequent lamination to realizecosmetic benefits.

Print blockers can be used behind the barrier coatand/or skin coat to provide further protection againstprint through from subsequent layers. The next layeror two should be a heavier mat or chopped roving,depending on the ultimate thickness desired. Thisprovides for fast laminate build-up. Anotheradvantage of starting the laminate with mat versuswoven roving or cloth is that it distances the fabriclayers from the laminate surface, minimizing fiberpattern.

The next layers can be fabric layers such as wovenroving or cloth. Woven roving should be used wherestrength is critical. Otherwise, 6 to 10 ounce cloth isused for a better-finished surface than roving. Use offabric in the final layers of the laminate allows theoperator to squeegee hard on the surface to removetrapped air bubbles and excess resin. For maximumstrength, succeeding layers should alternate matand woven roving. It is not usually good practice touse consecutive layers of woven material becauseof poor interlaminate bond and a higher chance forporosity.

6. LAMINATION METHODS—General preparation forlamination is as follows:

• Check all equipment and lines for contaminationsuch as flushing solvent, water, or oil.

• Check the temperature of the shop, mold, resin,catalyst, and reinforcing materials to ensure thatthey are within the appropriate range (typically



Page 6 of 11


LAMINATION METHODS continued:60ºF to 95ºF).

• Completely calibrate the equipment asdescribed previously in this chapter.

• Mix the resin as needed, according to themanufacturer’s direction.

When using spray equipment, it is recommended tomake a test spray to check the spray pattern. Whenusing spray-up equipment, a test spray should also beused to check glass dispersion and wetting.

Before laminating behind gel coat or barrier coat, checkthe film to make sure that it is ready for lamination bytouching it. If no material transfers, it is ready forlamination. Due to its high vapor density, styrene vaporstend to accumulate in low portions of the mold. Highstyrene vapor concentration tends to retard the cure of agel coat film. Monitor initial film curing by checking awell-ventilated area like the trim flange, but the final filmcure should be checked in low areas.

When laminating behind a skin coat, check the skin coatto make sure that it is thoroughly cured. The skin coatmust be thoroughly cured prior to subsequent laminationto realize cosmetic benefits. The approximate extent ofcure can be measured with a Barcol impressor. TheBarcol impressor measures the hardness of the resin.Resin hardness is related to cure. The further the cureprogresses, the harder the resin becomes. Typically,skin laminate resins should reach a minimum Barcolhardness of 20 prior to subsequent lamination.

A. Spray-up Methods

1) Spray a thin mist coat of resin on the mold tohelp with fiber wetout at the surface.

2) Next, spray the first layer of chop. The layershould be sprayed in two passes with thesecond pass being at right angles to theinitial pass. Overlap strokes byapproximately 50 percent. Keep the gunperpendicular to the mold to ensure auniform fan pattern. Maintain a constantspeed throughout the spraying to ensureeven material distribution. A quick rollout ofmaterial between passes may help preventsagging or sliding on vertical surfaces.

3) After spraying, completely wet out andcompact the glass with lamination rollers orbrushes. Brushes often work best in corners

or areas with complex geometry. Payspecial attention to removal of air bubbles orvoids, particularly at the gel coat surface.Voids at the gel coat surface can createcosmetic defects and lead to blistering.

4) After rollout, verify that the thickness of thelaminate is within the design range by usinga mil gauge.

Larger parts may need to be sprayed in sections.The size of each section will depend on the availableworking time and manpower. Sections should besized so that they can be thoroughly wet out prior toresin gelation.

B. Hand Lay-up Methods

For best control of resin-to-glass ratio and forminimizing air voids, textile constructions shouldalways be backwet. Resin is applied to the moldsurface, the dry ply is placed in the liquid resin, andthe ply is wetted by working the resin through fromthe bottom up. This ensures that the air is removedaway from the surface.

1) Trim the required number of roll goods pliesto the desired size and shape.

2) Wet the surface of the mold with a sufficientamount of resin.

3) Position the first ply on the mold. Trim theply as required to fit the mold.

4) Wet out the glass and remove air bubbleswith lamination rollers, brushes, orsqueegees. Brushes often work best incorners or areas with complex geometry.Add additional resin as required tosufficiently wet out the ply.

5) Repeat this procedure until all plies are inplace and wet.

6) Carefully inspect the laminate for wettingand air voids. Touch up with rollers orbrushes as needed. Remove any excessresin with a paint roller or brush.

Some laminate designs utilize coring materials toincrease the laminate stiffness while minimizing theadditional weight. Coring materials can beincorporated into the laminate by bedding them priorto resin gelation. The bedding layer should be thickenough for adequate bonding, but thin enough toprevent print-through.



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Hand Lay-up Methods continued:1) Laminate the bedding layer using the

methods discussed above.2) Wet the side of the core material that will be

applied to the laminate with a thin coat of resin.3) Position the core on the laminate and roll

over the surface, applying pressure to ensure goodsurface contact.

After lamination is complete, the laminate must beallowed to cure adequately prior to demolding. Thedefinition of adequate depends upon the part andprocess design criteria. The amount of time requiredto achieve adequate cure depends on the resin, thetype and amount of catalyst used, and thetemperature. Premature demolding of a laminatecan lead to print or distortion as the laminatecontinues to cure outside the mold. As previouslydiscussed, the Barcol hardness can be used as anindicator of cure.

After gelation and the peak exotherm temperaturehave occurred, it is possible to accelerate theremainder of the cure by exposing the part toelevated temperatures. This process is commonlyknown as postcuring. There are many benefits ofpostcuring composites. The ultimate mechanicalproperties are more easily achieved throughpostcure. If the postcure is done while the part is stillin contact with the mold surface, the parts will bemore dimensionally stable and resistant to print anddistortion during service. Postcuring can also driveoff unreacted monomer to reduce odors in thefinished part.

7. EQUIPMENT, TOOLS, AND SUPPLIES—Thefollowing is a list of equipment, tools, and supplies thatshould be readily available in the lamination shop:

A. Equipment needed includes:

1) Spray booth with filter, exhaust fan, metal-lined sliding doors, ample walking spacearound molds, good lighting.

2) Air compressor (don’t skimp on size—specify an air dryer; use accumulators withlarge water extractors). It is recommendedthat all hand tools be air operated foroperating costs and for safety reasons (non-sparking).

3) Cutting table for glass reinforcement (not

needed for spray-up), 60-inch wide rack onone end for mounting rolls of glass, two rolls.

4) Lamination equipment (as discussed earlierin this chapter and per manufacturers’guidelines).

5) Monorail and hoists for heavy parts, boatsand shower stalls.

6) Dollies or conveyor track for moving moldsaround plant.

7) Air hose, additional water traps, connectors,air regulators.

8) Air-powered, gear-driven mixer for mixingresin.

9) Storage bin—heated or dehumidified forglass materials.

10) Fire extinguishers around plant; consultinsurance carrier and local safety officials forproper type and location.

11) Scales for weighing ingredients (ounces andgrams).

B. Tools needed include:

1) Large scissors for cutting roll goods andsmaller ones for individual tailoring duringlay-up.

2) Paint brushes—3-inch and 4-inch, solvent-resistant.

3) Rollers—plastic and aluminum, such as 1-inch by 3 inches and 2 inches by 12 inches,and corner rollers. Nap rollers are used toredistribute resin.

4) Squeegee material.5) Hand grinders for smoothing exposed

surface and edges.6) Buffers for applying rubbing compound,

cleaner, and glaze.7) Putty knives for bonding, filling, repairing.8) Air-powered drills for hardware, trim, other

attachments.9) Linoleum knives for trimming edges of part

in mold.10) Wrenches for bolting molds together.11) Clamps for holding inserts to wet laminate

while curing.12) Measuring container for measuring catalyst.



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C. Auxiliary supplies:

1) Sandpaper—80 to 600 grit, wet or dry.2) Solvent for cleanup.3) Covering for floors under laminating area.4) Cans—1 gallon and 5 gallon, for resin and

solvent of appropriate type.5) Sponges for washing molds.6) Mold cleaner, mold sealer, and mold wax.7) Wash basins—for cleanup.8) Solvent dispenser can.9) Rags.



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Page 11 of 11

OPEN MOLDING: Lamination—Secondary Bonding

Composites

Applications Guide

Part Four, Chapter V.5

Copyright 2008In This Chapter1. Introduction2. Conditions Affecting Secondary Bonding3. Resin Chemistry and Secondary Bonding4. Surface Preparation5. Secondary Bond Evaluation

1. INTRODUCTION—Secondary bonding isdefined as fabrication of a new laminate (secondarylaminate) onto a previously cured laminate (primarylaminate). The term secondary bond refers to thechemical and/or mechanical interaction between theprimary and secondary laminates. Although chemicalbonds are stronger than mechanical bonds, both typesof bonds are necessary to optimize secondary bondstrength.A chemical bond is formed when the resin from thesecondary laminate reacts with available chemical siteson resin of the primary laminate. Available (or unreacted)sites on the surface of the primary laminate can resultfrom an under-cured laminate surface, otherwise knownas an air inhibited surface. The amount of chemicalbonding that occurs depends upon the number of theseavailable sites.A mechanical bond is formed when resin from thesecondary laminate flows into and cures in rough areason the primary laminate’s surface. This interactioncreates an interlocking force mechanically holding thetwo laminates together. The open sides of most openmolded laminates have some roughness that will allowmechanical bonding. Surface roughness can be createdby mechanical abrasion.Generally, shops with slower turnover of parts have thegreatest concern with secondary bond adhesion.Examples of shops with long process times include largecustom yachtbuilders or shops making smaller, moreintricate FRP parts that are laminated over extendedperiods.2. CONDITIONS AFFECTING SECONDARY

BONDING—There are many conditions that can affectthe ability of a secondary laminate to form a strong bondwith the primary laminate. These conditions include:A. Temperature—Exposing a cured laminate toelevated temperatures allows the laminate to obtain agreater degree of cure. This greater degree of cure isgood for the overall properties of the laminate, but notgood for secondary bonding. This greater degree of curereduces the number of unreacted sites on the surface ofthe primary laminate thus limiting the amount ofchemical bonding that could occur with the secondarylaminate.B. Humidity—High relative humidity has theopposite effect on the primary laminate. Humidity slowsdown the surface cure and increases the number ofunreacted sites. These unreacted sites are thenavailable to form secondary chemical bonds.C. Surface Contamination—On the primarylaminate, surface contamination can affect both chemicaland mechanical bond strength. If the primary laminate isnot cleaned properly, the secondary bond can becompromised, and the secondary laminate cure could beaffected as well. Common contaminants that detractfrom secondary bonds include grinding dust, compressoroil, water droplets from dew, and cleaning solventsD. Ultra Violet Radiation or Exposure toSunlight—Exposure to sunlight has the same effect asexposure to elevated temperatures. Exposure to UV rayshelps to speed the cure rate at the resin surface andreduces the number of bonding sites available. Iflaminates made with DCPD-based resins are exposed tosunlight at any time before a secondary bond is formed,the bonding surfaces must be ground to remove allvisible gloss.E. Time—The time between cure of the primarylaminate and application of the secondary laminate alsoaffects secondary bonding. In general, the shorter thetime between these steps the better. The more time thatelapses between primary laminate cure and secondarylaminate application, the further the cure of the primarylaminate will progress. Extended time prior to applicationof the secondary laminate also increases the chance ofexposure to elevated temperatures, contamination, andsunlight.



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OPEN MOLDING: Lamination—Secondary BondingCopyright 2008

3. RESIN CHEMISTRY AND SECONDARYBONDING—The type of resin used by the fabricatorsignificantly influences the degree of secondary bondingthat can be obtained. As mentioned in the previoussection, there are numerous conditions that can affectsecondary bonding regardless of resin type. However,resin type plays a major role and must be considered.For the purpose of this discussion, the resin types thatwill be compared for secondary bonding areorthophthalic and DCPD resins.A. Orthophthalic Resins—Orthophthalic resinshave proven to be very forgiving in secondary bondingapplications. Orthophthalic resins are air-inhibited, whichmeans that they have poor cure in the presence ofoxygen. The poor cure is manifested as tackiness on theopen side of a laminate. Poor surface cure is a benefitfor secondary bonding since there are a relatively largenumber of unreacted sites on the primary laminate thatare available to react with the secondary laminate. Inaddition, the poor surface cure characteristics oforthophthalic resins means that the degree of surfacecure will not progress as quickly with time or exposure toheat and sunlight as for other resin types.Primary laminates made with orthophthalic resins thatare stored in a cool, dark location and kept free fromcontamination can be used successfully in secondarybonding applications without extensive surfacepreparation for several weeks.Fabricators need to be aware that some orthophthalicresins contain additives to reduce the surface tack.These additives form a film on the open side surface ofthe laminate and can be detrimental to secondarybonding. The most common additive used is paraffinwax.B. DCPD Resins—DCPD resins have been widelyaccepted by FRP composites fabricators for reasonssuch as tack-free cure, good cosmetics, low shrink, lowcosts, and emissions compliance. However, the tack-free cure means that DCPD resins are not air inhibitedand have poor secondary bonding characteristics sincethere are relatively few unreacted sites on the open sideof the laminate. Exposure to heat and sunlight furthercure the surface, resulting in even fewer unreacted sitesfor secondary bonding.Primary laminates made with DCPD—containing resinsthat are stored in a cool, dark location and kept free fromcontamination — can be used successfully in secondarybonding applications without extensive surfacepreparation for only one to three days. After this time

period, the primary laminate must be mechanicallyabraded, and use of structural adhesives isrecommended to achieve a good secondary bond.C. Vinyl Ester Resins—VE resins offer the bestsecondary bonding capabilities. The VE resins are bestfor three reasons. First, the VE chemistry itself providesseveral bonding sites that remain active even in a fullycured laminate. Second, VE resins are more susceptibleto air inhibitions than other resins, offering an uncuredlayer in which the secondary laminate resin can co-mingle. Third, VE resins can be as much as three timesstronger that many polyester laminating resins. Forthese reasons VE resins are often selected for repairingaged laminates of various or even unknownconstructions.4. SURFACE PREPARATION— Mechanicalabrasion of the primary laminate surface is the bestapproach to ensuring a good secondary bond. Primarylaminates meeting the following conditions shouldalways be mechanically abraded prior to application ofthe secondary laminate:

• Laminates made using resins containing wax ormost other additives to reduce surface tack.

• Laminates that have been exposed to elevatedtemperatures.

• Laminates that have been exposed to UV light.• Laminates made using DCPD-containing resins

that have been cured for more than three days.• Laminates with glossy resin-rich surfaces.

Mechanical abrasion by sanding or grinding shouldremove all visible gloss and expose a fresh laminatesurface. It is advisable to sand down to expose somefiberglass.5. SECONDARY BOND EVALUATION—It isrecommended that each fabricator experiment withsecondary bonding using their materials and specificshop conditions. The most common method forevaluating secondary bonding is to perform a pull test.This type of testing does not quantify secondary bondstrength, but allows for assessment of secondary bondintegrity by evaluation of the failure location and failuremode. Users may want to perform several pull tests toevaluate various materials, storage conditions, storagetimes and/or surface preparation procedures. Testingshould be repeated when changing any materials (e.g.,glass, resin, or catalyst). The testing procedure isoutlined below.



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OPEN MOLDING: Lamination—Secondary BondingCopyright 2008

• Fabricate a primary laminate and store it underthe desired conditions and for the desired timeframe.

• Prepare the surface of the primary laminate.Place a strip of Mylar

®film or other release

material at one edge of the laminate to act as afailure initiation point.

• Apply the secondary laminate. The secondarylaminate should have the same dimensions asthe primary laminate. Allow the secondarylaminate to cure for at least 24 hours.

• Using the Mylar®

film location as a failureinitiation point, pull the two laminates apart.

If the failure occurs between the two laminates withoutfiber tear, the secondary bond is considered poor. If thefailure mode is within either of the two laminates asevidenced by fiber tear, then the secondary bond isconsidered acceptable. See the pictures on the previouspage for examples of poor and acceptable secondarybonds.The following are some general guidelines that will helpto provide the best secondary bonds possible.

Primary Laminate Secondary Laminate Primary Laminate Secondary Laminate

Poor Secondary Bonding Acceptable Secondary Bonding

DO DON’T

Do test secondary bonding when changing anymaterials (i.e., glass, resin, catalyst).

Don’t expose parts to direct or indirect sunlight.

Do sand or grind to improve adhesion to primarylaminate if laminating after 72 hours.

Don’t allow shop dust to coat the part.

Do use structural adhesives on parts being madeoutside of the acceptable secondary bonding window.

Don’t allow contaminates to come in contact with the part.



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Page 5 of 5

OPEN MOLDING: Field Service—Acyrlic Bonding




2. Acrylic Thermoforming Process

3. Resin Matrix Material Selection

4. General Application Guidelines

5. Adhesion Testing

1. INTRODUCTION—Acrylic plastics were introducedin 1936 and because of some distinguishing properties,have become a widely accepted liner material for thefabrication of tubs, showers, and spas. Acrylic plasticsoffer the fabricator a variety of colors and outstandingweathering characteristics, chemical resistance, and adurable, easy-to-clean surface for both the fabricator andend-user. Acrylic liners are typically backed with FRPlaminates made with polyester or vinyl ester resins.These laminates, when properly bonded to the acrylicliner, provide strength and stiffness to the finished part.

2. ACRYLIC THERMOFORMING PROCESS—Theprocess for creating the desired acrylic part shape iscalled thermoforming. Thermoforming is the shaping of apolymer sheet by the use of heat. This process can bebroken down into three stages: heating, forming, andcooling.

A. Heating—The first stage of the thermoformingprocess (i.e., heating) varies, depending on thespecific type of acrylic sheet being used. In general,a source of heat is applied to the acrylic sheet. Afterthe heat application at a predetermined temperatureand length of time, the sheet becomes soft and canthen be molded into the desired shape.

B. Forming—Forming creates the desired shape.This is accomplished by taking the heated acrylicsheet, laying the sheet over the mold, and by somemechanical and/or pneumatic means, molding theacrylic into the desired shape.

C. Cooling—The process of cooling returns the

acrylic sheet back to its original stiffness but now inthe desired part shape and dimensions. For specificdetails regarding the thermoforming process, thefabricator should contact one of many suppliers ofthermoforming machines. The suppliers of thesemachines can thoroughly discuss all parameters andoptions related to the thermoforming process.

3. RESIN MATRIX MATERIAL SELECTION—Numerous options for backing thermoformed acrylicsheeting are now available from resin suppliers. Theresin types typically used for backing up acrylic areeither polyester or vinyl ester resins.

A. Polyester Resins—The majority of acrylicbackup laminates are fabricated with polyesterresins. Orthophthalic resins are common, but othertypes of resins can be used as well. Not all polyesterresins adhere to all types of acrylics. Resinsselection is significantly influenced by adhesionconsiderations.

Polyester resins can be used unfilled or filled.Unfilled or neat resin application generally providesbetter adhesion than filled application, but is alsomore expensive.

1) Neat resin is defined as applying only thepure resin and fiberglass behind the acrylic.Better adhesion properties are oneadvantage to applying a neat resin layerbehind the acrylic. A disadvantage to usingneat resin is cost to the fabricator.

2) Filled resin systems use inorganic materialssuch as alumina trihydrate, calcium sulfate,and/or calcium carbonate added to the resin.There are many advantages to using a filledresin system, such as lower matrix cost,increased flame retardancy, and reducedvolatile organic emissions. However, fillerscan detract from the adhesion of the resin tothe acrylic substrate. Because fillers vary,the type and amount used (typically between30 to 60 percent) can affect the resin



Page 1 of 6

OPEN MOLDING: Lamination—Acrylic BondingCopyright 2008

viscosity and cure characteristics.Fabricators should work with the resinsupplier in order to develop a resin systemsuitable for the fabricator’s specific process.Another parameter that must be consideredwhen using a filled resin system is the typeand amount of fiberglass reinforcementapplied to the part. Typical glass contentsrange from 15 to 30 percent and can be thechopped roving applied by spray-up, orchopped strand mat applied by hand lay-up.The type and amount of glass reinforcementdirectly affects mechanical properties of thefinished part. The fabricator is ultimatelyresponsible for determining the amount ofreinforcement required to obtain the desiredend use engineering design.

B. Vinyl Ester Resins—Vinyl ester resins aretypically used as acrylic backup resins whenimproved water resistance or thermal properties arerequired. Spas and hot tubs are examples of such arequirement. The vinyl ester resins are typicallyapplied as a thin laminate next to the acrylic, and theremainder of the backup laminate thickness is builtwith a more economical polyester resin. As withpolyester resins, not all vinyl ester resins adhere toall acrylics. The value of the vinyl ester resin is lost ifthe product does not adhere to the acrylic.

4. GENERAL APPLICATION GUIDELINES—Once theacrylic shell has been properly clamped and supportedto the laminating stand, the acrylic should to be cleanedto remove contaminants such as dust, moisture, andother liquid materials. These contaminants can interferewith the resin’s ability to adhere to the acrylic or affectthe curing characteristics of the resin matrix. Possiblemethods for cleaning the acrylic include:

• Use of compressed air to remove unwanted dust• Use of an approved cleaner (recommended by

the acrylic sheet supplier to remove moistureand/or other liquid contaminants)

Before any resin matrix material is applied to the acrylicshell, the fabricator should make sure all manufacturingprocess parameters have been checked. Theseparameters include but are not limited to:

• Filler is mixed properly into resin.• Resin and shop temperatures are within the

resin supplier’s recommended guidelines.• If using a chopper gun, the gun is in properworking condition.

When the fabricator is ready to apply the resin matrix, agood recommendation is to either spray or brush on athin layer or mist coat of resin directly to the acrylic shell.The mist coat helps to ensure that there is sufficientresin next to the acrylic to provide adhesion.

After application of the mist coat, the first layer of resinand glass reinforcement can be applied. This layerneeds to be completely and carefully wet and rolled out.All air voids must be removed to ensure a completebond between the laminate and the acrylic. At this point,the fabricator can continue with the next layer ofreinforcement or allow this layer to cure beforecontinuing.

Each fabricator must determine a preferred specificlamination sequence. Some factors to consider are:

• Resin cure characteristics• Filler loading• Acrylic draw thickness

All these factors affect the laminate exothermtemperature. Low exotherm temperatures can be anindicator of poor cure. Poorly cured laminates will havelow physical properties and poor adhesion. Highexotherm temperatures can cause cosmetic issues,especially in areas where the acrylic is relatively thin.

This testing should be repeated on a regular basis toensure that proper fabrication procedures are beingfollowed. This testing should also be done when anymaterial change is made, including changes in cleaners,acrylic, resin, filler, catalyst, and glass fiber.

The final stage of the process is the trimming andaddition of any plumbing or external hardware. It isrecommended that the resin matrix be allowed toproperly cure and cool down before any such work isperformed. A good indicator of resin cure is to check theBarcol hardness of the backup resin. Ideal Barcolhardness is a minimum of 20 HB (934). Performing suchwork before the resin has been allowed to cure properlycan result in stress fractures in the part and minimize theresin’s adhesion properties to the acrylic. It is the soleresponsibility of the fabricator to determine when thesetypes of operations can be performed (see the followingsection on adhesion testing).



Page 2 of 6


5. ADHESION TESTING—Before Cook Compositesand Polymers makes a resin recommendation for anacrylic backup application, CCP offers to performadhesion testing for the fabricator. However, CCPcannot duplicate all of a fabricator’s conditions. Eachfabricator should design a suitable internal method toperiodically check adhesion, using their specificmaterials and conditions.

The perfect time for the fabricator to check adhesion iswhen the part is trimmed. The excess flange materialcan be observed for proper laminate rollout and wetting.Good adhesion can be determined by breaking a piecein half. Good adhesion is characterized by theappearance of resin and fiberglass left behind on theacrylic. This indicates laminate failure and not failure at

the acrylic and laminate interface. Caution should betaken if using this method because the flange acrylicarea is typically thicker than the remainder of the part. Itis easier to obtain a good bond over a thick acrylic thanover thinly drawn sections of acrylic, partly because ofless change to the acrylic polymer structure during the

thermoforming process.

The most common method for evaluating acrylic bondingis to perform a pull test. This type of testing does notquantify secondary bond strength, but allows forassessment of secondary bond integrity by evaluation ofthe failure location and mode. The testing procedure is:

Acrylic Laminate Acrylic Laminate

Poor Acrylic Adhesion Acceptable Acrylic Adhesion

A. Prepare a thermoformed section of acrylicper standard production procedures. It is importantto use thermoformed acrylic since the thermoformingoperation influences adhesion. Place a strip ofMylar

®film or other release material at one edge of

the laminate to act as a failure initiation point.

B. Apply the backup laminate per standardproduction procedures.

C. Allow the backup laminate to cure to a Barcolhardness of at least 20 (934).

D. Physically separate the laminates at thefailure initiation point.

If the failure occurs between the acrylic and laminatewith little or no fiber tear or pullout, the adhesion isconsidered poor. If the failure occurs within thelaminate with significant fiber tear or pullout, theadhesion is considered acceptable. See the pictureson the previous page for examples of poor and

acceptable acrylic adhesion.

Finally, fabricators have the option of quantifying theadhesion by performing ASTM C297 for flat-wise tensilestrength. For more information on this type of testing,please contact a third party mechanical testing facility orCCP representative.



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OPEN MOLDING: Field Service—Acyrlic Bonding




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Page 6 of 6

OPEN MOLDING: Lamination—Troubleshooting



In This Chapter1. Lamination Troubleshooting

2. Equipment Troubleshooting

1. LAMINATION TROUBLESHOOTING—Even underthe best of conditions, problems can occur due toaccidents, mistakes, and unanticipated events.

Listed on the following pages are some of the morecommon laminate problems, although other problemscan occur (it is impossible to anticipate every plantcircumstance that can cause problems).

COMMON LAMINATE PROBLEMS, CAUSES, AND SOLUTIONS

Problem Cause Solution or Items to Check for

Color variation in the laminate ............... Hot/cold laminate .......................

Uneven laminate ........................

Mix in catalyst well; reduce percentage of catalyst; resin puddles;

moisture contaminated glass.

Check spray pattern.

Cure time—long or short ....................... Various ....................................... Check percentage of catalyst and type; temperature; laminate

thickness; gel time; contaminations.

Delamination

a) From gel coat ....................

b) Between laminates ............

Contamination ...........................

Undercured/overcured ...............

Application .................................

Resin .........................................

Cloth against cloth .....................

Uncured......................................

Dust on gel coat; mold release build-up dissolved by gel coat; gel

coat with surfacing agent (wax).

Lay-up too soon/too late.

Poor impregnation, resin-rich.

Too much wax in resin; weak resin; check grade and physicals.

Use mat or chopped glass between plies.

Check percentage of catalyst; temperature; pulling green.

Dimples in gel coat ................................ Particles in laminate.................... Check for excessive binder on mat (one side may be worse than the

other). Trash or dust between gel coat and laminate; gel particles in

resin.

Drainout

a) No dry glass ......................

b) Dry glass ...........................

Resin-rich ..................................

Resin too thin .............................

Long gel time..............................

Reduce resin-to-glass ratio; avoid excess resin application.

Use a higher thixotropy resin.

Increase catalyst where allowed; check temperature.

Gel time—too long or short ................... Various ....................................... Check percentage of catalyst and type; temperature; laminate

thickness; gel time; contaminations.



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OPEN MOLDING: Lamination—TroubleshootingCopyright 2008

Glass pattern or waviness found in gel

coat

a) When part is pulled ...........

b) After part is pulled .............

Resin shrinkage or heat .............

Thin gel coat ..............................

Undercured gel coat ..................

Laminating process.....................

Post cure ....................................

Check catalyst level, temperature, use lower exotherm resin, avoid

resin puddling, thin gel coat, undercured gel coat.

Use a minimum of 18 mils.

Use a minimum of 1.2 percent MEKP; temperature should be at least

60ºF (18ºC).

Too much laminate at one time (use a skin coat); woven roving or

cloth too close to gel coat.

Too low a catalyst level; temperature too low; liquid contaminated;

resin exotherm too low; demolding too soon; gel coat too thin.

Glass pickup on roller ........................... Rolling near gelation ..................

Styrene evaporation ...................

Rolling too fast ...........................

Glass percentage too high .........

Dirty rollers .................................

Adjust gel time.

Dip roller in styrene or fresh catalyzed resin. Keep air movement

across laminate to a minimum.

More deliberate rolling.

Increase resin.

Change solvent.

Hot spots .............................................. Overcatalyzing ...........................

Resin-rich areas .........................

Unbalanced laminate .................

Check equipment; catalyst, and resin sides for clogs, surging, drips;

purge catalyst line.

Reduce resin content.

Check thickness of different areas.

Resin crack ........................................... Pulling too soon .........................

Too hot ......................................

Do not pull undercured parts.

Resin puddles; excessive catalyst; resin too high in exotherm.

COMMON LAMINATE PROBLEMS, CAUSES, AND SOLUTIONS

Problem Cause Solution or Items to Check for

Strength (low impact) or cracking .......... Insufficient glass .......................

Demolding .................................

Part too thin; weak resin.............

Check glass-to-resin ratio.

Rough demolding; too much twisting and flexing.

Increase thickness; check grade and physicals.

Soft spots .............................................. Unmixed catalyst .......................

Water, solvent or oil (may appear

as whitish areas)........................

Check equipment; catalyst and resin sides for clogs, surging, drips;

purge catalyst line.

Check air lines and solvent; rollers must be free of solvent.

Voids (air bubbles) ................................ Entrapped air ............................. Poor rollout; slow wetting glass; resin-starved areas; resin viscosity

high; filler level high; resin drainout.

Warpage of parts .................................. Unbalanced laminate ................. Use symmetrical layup; back spray laminate with gel coat or enamel.

Wetting (poor) ....................................... Viscosity too high ......................

Glass type or wetting properties.

Check viscosity; cold resin; moisture contamination. High resin solids.

Check type and grade of glass.



Page 2 of 7


2. EQUIPMENT TROUBLESHOOTING—The majorityof lamination today utilizes semi-automatic equipment.The care and operation of this equipment will determinewhether or not the laminate will achieve its maximumproperties and performance.

Fabrication equipment operators must be trained to useand maintain their equipment.

Anyone who uses spray equipment should have (andshould read) all the literature available from themanufacturer of the equipment. This includes partsdiagrams, setup instructions, operating instructions,maintenance requirements, and safety andtroubleshooting guides. If this information has not beenobtained or if a question arises, call or write both thecompany from which the equipment has been purchasedand the manufacturer. They will be happy to helpbecause they want the equipment used efficiently,correctly, and safely. Also, they will have generalliterature on spraying and technical service people toprovide assistance.

Always remember the investment in the equipment andthat it was purchased to do an important job. If it is notmaintained and if worn parts are not replaced, theinvestment will be lost and the equipment will not do thejob for which it was selected and purchased.

One method that can be used to determine if a cure-related problem is caused by material or equipment is tomake a small test part where the catalyst is mixeddirectly in the resin. If this part does not exhibit theproblem, then the cause is more likely with theequipment or operator. Another way to check is to run adifferent batch of material through the equipment;however, this could generate bad parts, making the firsttest method preferred.

A list of common problems that can occur withlamination equipment follows. Since there are numeroustypes of equipment in use, it is impossible to cover eachone individually or list all possible problems or solutions.See manufacturer’s literature for the type of equipmentin use, or contact the manufacturer.


Problem—Resin/Chopper/Laminate Suggested Causes and Remedies

Atomization poor (large droplets) .............................. Check air pressure, length of hose, hose diameter (which may be too small), clogged or

worn nozzle or air cap, stuck check valves, too much fluid flow, regulator not working

properly.

Balls in the catalyst flow meter drop............................. Bottom needle valve almost closed and vibrates, filter plugged, not enough CFMs (cubic

feet per minute).

Balls in the catalyst flow meter overshoot ............. Top valve wide open, turn 1 1/2 turns in—(Binks Injector)

Catalyst ball goes out of sight when pressured ............ Catalyst level too low—insert special gasket with 0.013 hole over delivery tube (Binks

injector), air in flow tube.

Catalyst injector balls fluctuating.................................. Catalyst needle valve vibrating or too close to seat—open or tighten packing, not enough

or fluctuating CFMs, dirty catalyst filter.

Catalyst valve—burst of catalyst .................................. Weak spring due to aging. If Binks, use Plug Groove valve at the gun. If hose within a

hose, check for broken catalyst line.

Cavitating pump—sucks air ......................................... Remove siphon tube, put pump directly into resin—if it pumps okay—cavitation is due to

the siphon system leak, pump too small, cold or high viscosity.

Check ball stuck .......................................................... Residue after flushing, vapor lock. Use piece of wood to free ball or tap side of pump.

Chopper will not run or runs slowly ........................ Loss of air, check CFMs; regulator not on; rubber roller adjusted too tight.



Page 3 of 7



Problem—Resin/Chopper/Laminate Suggested Causes and Remedies

Drips (Gun):

Fluid .................................................................

Catalyst.............................................................

Solvent..............................................................

Worn, clogged, or bent needle, seating adjustment of needle, overspray on gun, worn packings or

seals, loose connection.

Worn seat or seals, damaged air valve, trigger out of adjustment, overspray on gun, loose

connection, clogged valve or seat, gun head not aligned to gun body, fan control may trap catalyst

in dead air space and drip catalyst out of air horns.

Clogged or worn valve, worn seals, sticking needle or button

Gelled hose .......................................................... Bad fluid nozzle, bad seat.

Glass (chopped) not uniform in length................... Worn or damaged blades; worn rubber roller; incorrect roller adjustment.

Glass pattern narrow............................................. Chopper angle wrong; chopper air too low.

Glass off to one side ............................................. Chopper out of alignment; fluid nozzle worn or clogged.

Glass-to-resin ratio varies ..................................... Chopper air not regulated; pressure dropping before compressor kicks on—install regulator and

set below the compressor’s kick-on pressure; prewetting and extra wetting not accounted for.

Hot spots .............................................................. Uneven laminate thickness, catalyst or resin surging, purge catalyst line before starting, catalyst

drops.

Shaft of pump drops an inch or two—shudders .... Starved pump—check filters or worn internal packings. Check for worn packing by stopping pump

at top of stroke—if with no material flow shaft creeps down, packing is worn.

Shaft of pump (material coming up around) .......... Loose or worn seal—clean and tighten, stop pump in down position when system not in use, worn

shaft.

Siphon kit jumps ................................................... Dirt on check ball in pump.

Slow gel time and/or cure...................................... Check catalyst and material flow, oil, or water contamination. Check gun trigger for proper

activation. If slave pump, check for air bubbles.

Surging:

Material ............................................................

Catalyst.............................................................

Inconsistent or low air pressure on pump, worn or loose pump packing, out of material, sucking air

through loose connection, balls not seating in pump (dives on down stroke—bottom ball; fast

upward stroke—top ball; flush pump), filter plugged, siphon line has air leak, screens plugged, too

much material flow, cold or high viscosity, plugged surge chamber.

Inconsistent or low air pressure, out of catalyst, check valve sticking in gun or catalyzer, loose

connection, screen plugged. If Binks equipment install Plug Groove valve at the gun, keep hoses

straight rather than coiled.

Fingers in pattern (airless):

Material ............................................................

Catalyst.............................................................

Pump pressure too low, worn tip, too large of tip, viscosity too high.

Worn tip, low pressure, wrong tip, viscosity too high, too large a fan.



Page 4 of 7

Tips spitting or trigger will not shut off ................... Worn seat or worn needle or weak spring, check packing.

Trigger stiff............................................................ Bent needle, bent trigger, worn needle guide.

Water in air lines ................................................... No extractor, extractor too close to compressor—should be no closer than 25 feet, all take-offs

from main line should come off the top.

Worn packings...................................................... Pump overheating from being undersized, high pressure or pumping without any material, do not

let pumps jackhammer—no more than one cycle (both strokes) per second—use glass reinforced

Teflon® packings. Keep idle pump shaft in down position to keep dried material from damaging

packings.



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Page 6 of 7







Page 7 of 7

OPEN MOLDING: Painting Polyester Gel Coats


Part Four, Chapter VICopyright 2008


2. Surface Preparation

3. Baking

4. Other Systems

1. DESCRIPTION—If painting of a gel coat part isdesired, the most durable paint system to employ is acatalyzed urethane.

In general, two-component acrylic urethane or polyesterurethane enamels maintain very good gloss and colorretention when subjected to prolonged and severeatmospheric conditions. They will normally cure atambient temperatures to a very tough, abrasion-resistantfilm with exceptionally high gloss.

Reputable sources for quality coatings include:

• DuPontwww.dupontrefinish.com

• Sherwin-Williams Co.www.sherwin-automotive.com

• U.S. Paint Corporation (AWL Grip)www.uspaint.com

2. SURFACE PREPARATION—When recoating(painting) a polyester gel coat, it is very important thatthe surface be clean and free from mold release agents,oil, grease, and other surface contaminants.

Follow the coatings manufacturer’s directions for surfacepreparation, mixing, reducing, sweat-in, pot life,application coverage, film thickness, drying time,cleanup, physical data, precaution and safety, and otheraspects.

If using for water immersion service (boats, tubs,showers, pools, spas, etc.), be sure that the paint isrecommended for such use.

A. In the absence of surface preparation—instructions, a minimum surface preparation wouldinclude washing thoroughly PRIOR TO and AFTERsanding with CLEAN rags and V. M. & P. Naphtha(or coatings manufacturer’s recommendations) toremove all contaminants.

B. Sand all gel coat surfaces with a medium gritsandpaper such as numbers 120, 220, or 320 toroughen the surface. Follow with an overall finesanding to a smooth surface using number 400 gritsandpaper.

3. BAKING—Customer experience has demonstratedthat gel coated laminates can be post-baked attemperatures up to 285ºF for as long as two hours.

NOTE: If the fiberglass part is not completely curedbefore baking, distortion can occur during the bakecycle. It is better to prebake the part for one hour at thebaking temperature before sanding. Then sand andbake.

4. OTHER SYSTEMS—Other paint systems can beused but may not have the exterior durability ofcatalyzed urethane. Match desired durability with paintquality. See paint manufacturer’s recommendations.



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OPEN MOLDING: Painting Polyester Gel CoatsCopyright 2008



Page 2 of 3







Page 3 of 3

OPEN MOLDING: Field Service—Cosmetics


Part Four, Chapter VII.1Copyright 2008

In This Chapter

1. Defining Cosmetic Surface Quality for FRP

2. Sources of Cosmetic Flaws and Strategies for

Preventing Print and Distortion

1. DEFINING COSMETIC SURFACE QUALITY FORFRP—Cosmetic surface flaws go by many differentnames: print-through, distortion, heat lines, orange peel,dimples, waviness, glass print, pock marks, puckered,poor profile, glass pattern, balsa print, woven rovingchecks, rough surface, and heat distortion.There are various types of surface distortions that arecaused by different mechanisms. While not all types canbe neatly classified, all print distortion can be groupedgrossly into two sets:

• Small-term distortion (less than 0.05 mm)• Long-term distortion (greater than 0.5 mm).

Small-term distortions (orange peel, fish eyes, etc.) aregenerally found in the coating film thickness (paint or gelcoat) but also include distortions that show through theindividual fibers of the layer of reinforcement directlybehind the film.

Long-term distortions are those flaws that are larger andmay even disrupt the surface enough to be felt. Largerflaws seen during the application of the coating film suchas sag lines or curtaining are long-term distortions. Othercommon examples are the transfer to the surface ofpatterns of the reinforcing fabrics and cores.

2. SOURCES OF COSMETIC FLAWS ANDSTRATEGIES FOR PREVENTING PRINT ANDDISTORTION

A. Tooling—The quality of the mold surface is theprimary source for print. A smooth, flawless partCANNOT be made from a distorted tooling surface.The surface quality of the part is only as good as thesurface quality of the mold. Every copy fabricated ina flawed tool will cost more in labor to restore than

fixing the tooling surface (see Part Eight onPolyester Tooling for more information).

B. Gel Coat—While gel coat is only designed toprovide color and gloss, distortions also occur in thegel coat film. Most gel coat cosmetic flaws are due toapplication mistakes. Heavy or uneven applicationcan cause the ripples and sags that show through tothe finished surface. Undercatalyzed (less than 1.2percent) gel coats do not cure properly and have lowheat distortion temperatures. Poorly cured gel coatsare easily distorted by the substrate laminate and byexposure to high temperatures.

Along with undercure, thin gel coat application is theleading cause of small-term fiber print-through.Because the fiber bundles of the glass are closer tothe surface, the shrinkage of the laminate aroundthe fiber also pulls on the gel coat film. Thicker filmsof gel coat are more resistant to showing the fiberprint-through. There are trade-offs with thickerapplication of gel coat. Problems such as sagging,porosity, cracking, and reduced weatheringresistance are more likely to occur.

C. Barrier Coats—Use of a barrier coat is aneffective method of increasing the distance of thereinforcing materials from the surface of the gel coatwithout the problems associated with thicker gelcoat. Barrier coats such as CCP’s ArmorGuard

®are

made with vinyl ester resins, which are two to threetimes tougher than typical pigmented gel coat andadd an unreinforced layer to the gel coat, which isnot prone to cracking. Besides fiber print blocking,barrier coats offer increased resistance to osmoticblistering.

D. Print Blockers—Use of a print blocker isanother method of distancing reinforcing materialsfrom the gel coat surface. Sprayable print blockersthat are formulated with high-grade resins willthermally insulate the gel coat from the shrinkage ofbulk lamination layers.



Page 1 of 5

OPEN MOLDING: Field Service—CosmeticsCopyright 2008

E. Reinforcement—Fibers used for reinforcingFRP must have the correct sizing for the matrix resinused. Fiber sizing for epoxy does not dissolve instyrene-based polyester and vinyl ester resins. If thefiber is not compatible with the resin, the resultantcomposite will have prominent fiber print. When thefibers are not thoroughly wetted by the matrix resin,micro voids along the fiber axis are left behind.During cure, these voids expand and cause the fiberprint pattern to be enhanced.

The type of reinforcement architecture alsoinfluences cosmetics. Laminates made with woven,stitched cloth, continuous roving reinforcements orcoring materials close to the gel coat surface showpronounced long-term print. Laminates made withcoring materials close to the gel coat surface withoutbedding into a random fiber layer or a veil also showpronounced long-term print. The resin rich areasbetween fibers and bundles shrink more than fiberrich areas. The pattern of this shrinkage transfersthrough to the surface.

The laminate sequence and cure cycle can alsoinfluence surface cosmetics. The heat of exothermof each lamination step must be controlled toprevent distortion caused by excessive shrinkage athigh temperatures.

F. Resins—Polyester and vinyl resins generateheat as they cure. This heat of reaction is masssensitive, meaning the larger the volume cured, thehigher the exothermic temperature.

There are several strategies for controlling theexotherm in a laminate. The most basic is to controlthe thickness applied during one cure cycle. This isthe time it takes for the resin in the laminated layerto gel and exotherm. The best example of controllingexotherm by ply thickness is in the traditional mold-building process. Using a conventional polyesterresin to build a tool, thin layers (less than 90 mils)are laminated over several days. This processallows the shrinkage to occur in small, controlledsteps while very little exotherm is generated,resulting in a distortion-free surface. Most productionschedules do not allow for this extended cure timeas in tool building.

Other strategies for exotherm control include:

• Resins formulated to suppress exotherm aredesigned to moderate the peak exotherm ofthe reaction by extending the duration of theexotherm phase of reaction. This results in alonger time to reach the ultimate cure. Thereis some penalty on speed of cure in thinsections with these versions.

• Catalyst level and types can be used tocontrol exotherm of each ply. Lowering thecatalyst to the minimum limit for the specificresin can help moderate exotherm. Lowercatalyst levels lower exotherm, but alsoextend gel time and cure and may bedetrimental to surface cosmetics.

• Methyl ethyl ketone peroxide (MEKP)catalysts blended with cumenehydroperoxide (CHP) are available, such asKC-70 from Arkema. These catalystsprovide exotherm control by diluting theMEKP with an alternative peroxide initiator.The CHP and resin have a lower heatreaction. Used properly, these systems canprovide exotherm control with negligibledelay of the final cure.

G. Process Factors—Faster production rates in anFRP fabrication process can be detrimental to goodsurface cosmetics. Faster gel and cure cyclesincrease the percentage of shrinkage. A partspending less time in contact with the moldincreases the chance for shrinkage to happen afterthe part is demolded (commonly referred to aspostcure). Parts that are demolded earlier in thecure cycle are also at risk for other problems, suchas cracking and dull finishes.

Hot, cold, or uneven temperatures in the fabricationshop can cause a host of cosmetic issues. If thetemperature is too high (more than 95 to 100°F (35to 38ºC), parts may demold in sections duringlamination. This is known as secondary prereleaseand leaves the areas of smooth finish where the partremained in contact with the mold adjacent to areasof fiber print. Uneven temperatures, such as oneside of the part near a heat source and the otherside near an open door, can also cause secondaryprerelease. Lamination in cold temperatures (lessthan 60 to 65°F [16 to 18ºC]) risks retarding the cureof the laminate. On demold, these parts may distortas they warm and finish curing later, producing a



Page 2 of 5


Process Factors continued:warped distorted surface. If the temperature is toolow, the cure may be permanently retarded. In thiscase the undercured part will have a low heat

distortion temperature. Depending on the color theexposed surface, sunlight may be enough to distortthe surface.



Page 3 of 5




Page 4 of 5







Page 5 of 5

OPEN MOLDING: Field Service—Gel Coat Weathering



In This Chapter

1. Introduction

2. Weathering Forces

3. Weathering Effects

4. Influences on Weathering

4A. Gel Coat Types

4B. Fabrication

4C. Part Maintenance and Materials

4D. Proactive Minimization

5. Weathering Tests

6. Additional Reading

1. INTRODUCTION—Gel-coated FRP parts are usedin a number of outdoor applications where they will beexposed to a variety of elements. Gel coats providedurable surfaces that are resistant to degradation fromthe elements. However, all gel coat surfaces will showwear and tear over time. This wear and tear is typicallyreferred to as weathering. It is important to note thatweathering of a gel-coated surface can be minimizedthrough regular preventive maintenance just as thepainted surface of a car will last longer with regularwashing and waxing. A program of regular preventivemaintenance is always more cost-effective than allowingthe gel-coated surface to deteriorate and thenundertaking a major restoration effort to restore thesurface to its original appearance.

The following includes an explanation of weatheringforces, the effects of these forces on the gel coatsurface, how weathering can be prevented or minimized,and how the gel coat surface can be restored ifweathering occurs.

2. WEATHERING FORCES—Once a part is made, itbegins to change because it is immediately andinevitably attacked by the environment. The attack isfrom:

• Light• Water• Pollutants• Temperature

These are strong forces which cause wooden boatowners to repaint and recaulk almost every year, andwhich cause cars to rust, vinyl to crack, and virtuallyevery synthetic material to need repainting.

A. Light—Light is a form of energy. The energy inlight is made up of different components orwavelengths. A rainbow displays light separated intoits individual wavelengths. Some of thesecomponents are stronger than others. Ultraviolet(UV) is considered to be the most destructivewavelength when it comes to weathering, but theothers cannot be ignored.

The energy in light attacks materials by breakingdown their molecular or polymer structure(degradation). This energy can cause a chemicalreaction to take place. This reaction is oxidation, andis noticed as color change (yellowing, chalking, orbleach fading).

B. Water—Water is called the universal solvent. Itwill dissolve more things than any other chemical.

Water attacks gel coats by dissolving or reactingwith them. It penetrates materials and leeches outimpurities or degraded materials. It can alsocontribute predissolved chemicals which can causestains or degradation. It can change a noncorrosivematerial into a corrosive material. As waterpenetrates it can also cause blistering.



Page 1 of 15

OPEN MOLDING: Field Service—Gel Coat WeatheringCopyright 2008

C. Pollutants—The environment is not sterile. Theatmosphere contains many foreign materials. Someof these are natural: pollen, mold spores, dust,aquatic grasses, organisms, and dirt. Others areman-made: smog, acids, oxides, etc., as in exhaustfrom manufacturing plants. Some are harmless,some stain, and some attack whatever they land on.

D. Temperature—Sunlight generates heat and willraise the temperature of a part. How much thetemperature will escalate depends on color. Whitereflects most of the sunlight and warms up onlyslightly (e.g., in 100°F (38ºC) air, white can reach120 to 130°F (49 to 54ºC)). Dark colors absorb moresunlight and warm up more (e.g., in 100°F (38ºC)air, black can reach 150 to 170°F (66 to 77ºC)).

As the part warms up, three things happen:

• The material softens slightly.• Additional cure can take place.• Chemical attack and water penetration rates

are increased (see the chart below).

EFFECT OF COLOR CHOICE ON SURFACE

TEMPERATURE UNDER SUNLIGHT

Surface Temperature °F (ºC)

Panel Color No Backing Foam Backed

White 120ºF (49ºC) 127ºF (53ºC)

Light Blue 127ºF (53ºC) 137ºF (58ºC)

Medium Blue 137ºF (58ºC) 157ºF (69ºC)

Dark Blue 144ºF (62ºC) 174ºF (79ºC)

Medium Red 128ºF (53ºC) 142ºF (61ºC)

Dark Red 137ºF (58ºC) 169ºF (76ºC)

Black 148ºF (64ºC) 173ºF (78ºC)

These panels were exposed to outdoor sunlight with

unrestricted ventilation of 100°F (38ºC) air.

3. WEATHERING EFFECTS—The effects of theweathering forces described above can be characterizedas follows: chalking, fading, and loss of gloss. Most ofthese changes are cosmetic. They appear on thesurface of the gel coat and do not affect its strength. Thesurface is sound, but does not look as it did originally.

A. Chalking—Chalking is the development of afine power on the gel coat surface. Chalking occurswhen the thin resin rich layer at the surface of thegel coat breaks down. The accumulation of this finepowder decreases the gloss of the part and alsoresults in the color appearing lighter. The chalk isstrictly on the surface and can be removed. Mosthouse paints are designed to chalk and then washclean when it rains. Gel coat chalk, however, doesnot simply wash off.

B. Fading—Fading is a uniform color change thatcannot be recovered. A faded surface has lessbrightness and intensity, resulting in a washed-outappearance. Fade can be measured as changes inhue (red, blue, yellow), chroma (brightness orintensity), and value (lightness and darkness). Sincechalking causes a color to appear lighter, it canmistakenly be interpreted as fade; however, chalkcan be removed and the surface appearancerecovered.

Different grades of gel coat will show varyingdegrees of fade. The type of polymer and pigmentsused in the gel coat affects the rate and amount offading. When pigment fade occurs the part typicallyretains its gloss, but will become lighter in color.Fading can also be the result of chemical exposurewith the chemical staining or bleaching the partsurface.

C. Yellowing—As you would guess from the term,yellowing is the change of the surface from itsoriginal color to a yellower shade. Yellowing istypically seen only in lighter colors. Darker colorstypically fade when weathered. Yellowing is causedby the reaction of light, water, air pollutants, andheat with any reactive sites in the gel coat, whichcan include aromatic structures, unpolymerizedmaleic or styrene, or by-products. Some of thesesites always exist. Achieving a good cure isnecessary to reduce these to a minimum.



Page 2 of 15


Yellowing continued:

Yellowing can be uniform or nonuniform across thepart surface. Usually nonuniform yellowing can beattributed to application. Streaks can be caused bychemical stains, residues, or by a covering that wasleft on the gel-coated surface which, therefore,shielded the surface from the environment.

D. Loss of Gloss—Gloss refers to the gel coat’sshine or how it reflects light. A surface that is high ingloss will appear shinier and reflect more light than alow-gloss surface. Any change in the surface (be it alight sanding, chalking, or dirt) will alter the gloss.CCP has found that parts restored after weatheringwill lose gloss faster upon re-exposure than will anew surface weathered for the first time.

E. Fiber Bloom—Non-gel-coated fiberglasslaminates can experience all the effects describedabove, but can also be susceptible to fiber bloom.Fiber bloom is the protrusion of the laminate’sreinforcing fibers through the part surface. Thisoccurs when the resin rich layer on the surface ofthe part breaks down, allowing the reinforcing fibersto “bloom” through the surface. Gel coat providesexcellent protection against fiber bloom.

4. INFLUENCES ON WEATHERING

A. Gel Coat Types

1) General

a) Resins—The weather and waterresistance of gel coats can be related tothe resin type used. For polyesters,certain glycols and acids impart betteryellowing, chalking, and blisterresistance to a polymer than do others.Vinyl esters typically have poorweathering resistance.

b) Other Ingredients—The otheringredients used in gel coats canimprove or reduce the weatheringcharacteristics of the base resin.Application, weathering, and blisterresistance have to be balanced. Theseingredients are:

• Fillers—type and amount• Pigments• Additives

Two types of additives that can significantlyaffect the weathering performance of gelcoats are UV absorbers and stabilizers. UVor light absorbers work by absorbing theharmful sunlight and converting it intonondestructive energy. Light absorberseventually are used up. They only slowdown and even out yellowing. The part willchange in color with time. Light stabilizerswork by scavenging free radicals formed inthe photo-oxidation process and inhibitdegradation. Light stabilizers are not usedup, but instead are regenerated in a cyclicprocess.

The effectiveness of UV absorbers and UVstabilizers is dependent on pigmentation andproduct series. For instance, UV absorbersare of significant benefit in clear ornonpigmented gel coats. However, UVabsorbers do not generally improve theweatherability of white-pigmented gel coats.UV absorbers can be of significant value incertain colors. Light stabilizers (HALS) canbe effective in improving weatherability ofpigmented gel coats.

Certain end-use specifications may requirethat UV absorbers be specifically added tothe gel coat. In these cases UV inhibitorsand/or UV stabilizers are added to the gelcoat products upon the customer’s writtenrequest. Since the effectiveness of suchadditives is not always known in a particularcircumstance, CCP cannot make any claimsor warranties as to their effectiveness in aparticular product or with a particular color.

2) Clears—Clear gel coats are the mostsusceptible to yellowing because of theabsence of pigment. Because of this, UVlight absorbers are useful in clears. The useof light absorbers in clears is a compromise.They add to the initial yellow color of theclear (as the better light stabilizers areyellow themselves) but this is balancedagainst slower yellowing upon aging.



Page 3 of 15


Clears continued:

Clears have greater gloss retention thanstandard gel coats due to the absence ofpigments and fillers.

3) Metalflakes—A metalflake system is a clearbacked by the metalflake in clear. Theweathering on the surface is the same as aclear, but now the effect of environment onthe flake itself must be considered. Somemetalflake is made by coating an aluminumfoil or aluminized Mylar

®sheet with a dyed

epoxy. The aluminum reflects the light backthrough the dyed epoxy coating, giving it thecolor of the dye. If the epoxy is not properlycured and the gel coat is not cured, thealuminum can be corroded and the color ischanged.

4) White and Off-White Gel Coats—Theweathering of whites and off-whites is partlycontrolled by the amount and grade oftitanium dioxide (TiO2) used. High exteriordurability grades of TiO2 are the best andalso the most expensive. Whites are veryforgiving as they do not show changes ingloss easily, but will yellow. White gel coatsare highly pigmented and will chalk morethan clears. The chalking is not asnoticeable because it is white on white, butgloss will suffer. Chalking is more noticeableon dark colors.

5) Colored Gel Coats—A wide variety ofpigment types are used to make colors. Allpigments do not weather equally. Normally,medium to dark colors do not yellow, but willchalk and fade. Color pigment must bechecked out carefully. Colors that weatherwell in paints may not work in polyesters.CCP uses pigments with provenweatherability in gel coat applications.

Accelerated weathering must be comparedagainst actual outdoor exposure (i.e., somecolors look good in the weatherometer, butafter six months in Florida will have fadedbadly). Many pigments will bleach out whensubjected to either acids or bases. Bluesand greens fade in color, while yellows and

reds turn brown or go darker.

EPA regulations limit the types of pigmentsthat can be used. At CCP, lead, chromate,and other heavy metal pigments have beendiscontinued.

6) Deep-Colored Gel Coats—Blacks, blues,reds, burgundies, and greens chalk as theyweather. They may do so at the same rateas other colors, but the whitish chalking ismore visible. This is because deep colorshighlight any chalking, making it stand out.Some colors absorb more sunlight,becoming hotter and weathering faster. Ingeneral, as they weather, clears, whites, andoff-whites will yellow; colors will fade; andblack and deep colors will chalk.

Colored gel coats, whether lighter or darker,have a greater tendency to discolor (lighten)and develop osmotic blisters when exposedto water than white or off-white gel coats.The severity of water-spotting or blushingwill depend on the length of time of theexposure, the temperature of the water,chemical makeup of the water, the darknessof the color, degree of cure, etc. Also notethat continuous use is more detrimental thanintermittent use. For example, boats storedon trailers or in dry dock are less likely todisplay the problem than boats left in thewater continuously.

B. Fabrication—The durability of a part is relatedto the care that is taken in making it. Good materialsused poorly will produce a poor part. Today’sincreased production rates leave very little marginfor error. Training and tight controls are a must.

Beware of making parts rapidly with the intention offixing them later. Repairs are costly and take awayfrom the ultimate quality of the part. Sanding andbuffing can hasten the chalking and loss of gloss ofgel coats. The ideal approach is to build quality in,rather than add it on (by patching).



Page 4 of 15


CAUTION: Patches will not weather (chalk andchange color) at the same rate as the original gelcoat. This phenomenon may be most noticeablewith bright whites, but is not necessarily limited tojust this color. Because of the different weatheringcharacteristics of a patch versus original gel coat, itis advised that patches be taken to a break point onthe part, such as an edge, tapeline, or wherehardware may be attached later, etc. If a patch mustbe made in a flat area with no break line, thecustomer is advised to determine if the differentweathering characteristics of the patch versus theoriginal gel coat are a significant cosmetic problem.To make this determination, perform an exposuretest on parts made and patched in the productionarea, using the exact patching technique andmaterials proposed.

Molds and equipment will get dirty and wear quickly;good maintenance is a must to assure production ofa quality part.

1) Molds—Weathering takes place at thesurface of the part, which mirrors the mold. Ifa mold has any dirt, dust, or a build-up on it,some will be transferred to the part. Forexample, polystyrene slowly builds up on themolds. Polystyrene yellows badly. If themolds are not properly cleaned, thepolystyrene is transferred to the part and willyellow. Do not use styrene to clean a moldfor three reasons:

a) Fumes can cause more polystyrene toform.

b) It can leave a thin residue of polystyreneon the mold.

c) The styrene may contain polystyrene,leaving it on the mold. Pure styrenestarts to form polystyrene after only 30days. Styrene, as it ages, will turnyellow, thicken, and eventually gel.Excessive wax left on the molds canalso be transferred to the part, whichmay yellow later.

2) Additions to Gel Coat—If the gel coat ismodified before spraying, its weatheringproperties can be changed.

Do not thin the gel coat without authorizationfrom the gel coat supplier. Do not addanything except catalyst without thesupplier’s permission, as the initial color andresistance to weathering may suffer.

3) Calibration—Inadequate calibration of sprayequipment will affect the weathering of parts.Too high (or too low) catalyst levels cancause parts to prematurely yellow or chalk. Ifthe catalyst is not well mixed with the gelcoat, inconsistent weathering can occur.Refer gel coat product data sheets providedby the manufacturer for catalyst type andamount. Poorly atomized gel coat will retainmore monomer, resulting in more yellowing.

4) Technique—The gel coat must be appliedas evenly as possible because inconsistentfilm thicknesses will cause nonuniformweathering. Also, apply in at least twopasses. One-pass spraying of thicker filmswill cause yellowing. Thinner films yellowless than thicker films. For high-visibilityareas such as boat decks, 12 to 16 milsmight be considered; however, resistance toprint-through and blistering would bereduced.

5) Cure—Poorly mixed catalyst will makevarious sections of a part weatherdifferently. Overcatalyzed parts or areas willbleach, fade, and chalk worse than anundercatalyzed part. Ambient and moldtemperatures in the plant must be 60°F(15ºC) or above to ensure proper cure.

C. Part Maintenance—Weathering can beinfluenced by the care the finished part receives.

Weathering starts immediately. It does not dependon whether the part is immediately sold or if it sits ata dealer.

FRP parts need to be washed, waxed, and takencare of like a car. They do not need repainting andcaulking each year like wooden boats, but they doneed care. A car dealer will wash his cars once aweek to keep them looking good. A professionalFRP dealer should do the same.

Chemicals and dirt can collect during storage. The



Page 5 of 15


Part Maintenance continued:

gel coat can be attacked or stained when chemicalscombine with rain or dew. They then can attack orstain the gel coat.

Following are some general instructions for keepingfiberglass parts looking almost like new (for furtherinformation, contact the manufacturer or suppliers ofcleaning materials):

• Wash monthly or more frequently, if needed.Wash with mild soap such as dishwashingsoap; avoid strong alkaline cleaners orabrasives.

• Wax the part with a good grade paste waxformulated for gel coat surfaces. Waxingfrequency depends on the level of exposureof the gel-coated part. Water will bead on afreshly waxed, gel-coated surface. Whenwater no longer beads waxing is needed.Once or twice per year is generallysufficient.

• Cover the surface with an appropriatebreathable material or shelter from sunlightwhen not in use.

For parts that have weathered and chalked:

• Wash the gel-coated surface.• Try a little wax in one area to see if this is

sufficient to restore luster. If not, use a fineglaze or rubbing compound, followed bywax.

If the part has weathered for some time and hasdeveloped a very severe chalk, rubbing compoundalone may not be strong enough to remove thechalking. Sand lightly with 600 (or finer) 3M

™

Wetordry™

paper, then follow with a fine rubbingcompound, glaze, and wax. Use finer paper, orpreferably use finest obtainable compound/glaze, toremove less severe chalking.

1) Cleaners—Polyester gel coats are veryresistant to water and other chemicals, butthe number of overly harsh cleaners that areavailable on the market is alarming. Avoidany strong alkaline (such as trisodiumphosphate) or highly acidic cleaners. Avoidbleach and ammonia. These materials, if leftin contact with polyester, may attack or

change the color. Any cleaner that is usedshould be in contact with the polyester theminimum amount of time required to do thejob. All cleaners are meant to attack dirt andremove it. The longer they remain in contact,the more they attack the dirt and the finish. Itis best to use mild detergents such as handdishwashing soap, which will work for amajority of stains and dirt accumulations. Ifunsure about using a cleaner, do two things:

a) Read the label and follow themanufacturer’s instructions. Usecleaners only on surfacesrecommended by the manufacturer. Useof cleaners on other surfaces could bedamaging. Cleaners normally used forwood or teak also may not beappropriate for fiberglass.

b) Run a test spot. Try it in aninconspicuous spot. If it discolors ordulls this area, do not use it.

2) Sanding and Buffing—The process ofsanding and compounding a new partsurface can cost three to six months of finishlife. For weatherability’s sake, it isadvantageous to operate with defect-free,high-gloss molds (and good procedures) sothat minimal finishing is required on the part.

The reason this causes a reduction inweatherability is that sanding andcompounding remove the thin, resin, richsurface which protects the part’s surfaceand imparts higher gloss.

Glazes give gel coats a glossy appearancewhen first applied. This is a temporary shinethat may disappear as it wears orevaporates. It is easy to be deceived withthis false gloss and fooled into thinking thegel coat is rapidly losing gloss when it isreally fugitive glaze. Again, the bestapproach is to build the gloss into the partthrough the mold surface finish.



Page 6 of 15


Part Maintenance continued:

3) Rubbing Compounds—There are a widevariety of rubbing compounds. Some arefaster cutting (more abrasive), some areslower. A rubbing compound is a fine, grittymaterial that is used to take off part of thetop surface. Compounds come in a numberof different types of grits, such assandpaper.

The coarser grits are faster cuttingcompounds, which have larger particles andremove more of the surface more quickly.Stay with the fine grits. These grits arecarried in a variety of liquids (lacquer,mineral spirits, water, and other vehicles).General tips are:

a) Read directions on use.

b) Do not use in direct sunlight. Thismakes the rubbing compound dry out.

c) Use clean pads to apply. Apply rubbingcompound liberally. Do a small area,(usually 3 feet by 3 feet) at a time. Ifusing a power buffer, use low RPM(1,700 to 3,000 RPM range). Keep thebuffer moving at all times. Do not applyheavy pressure. Heavy pressure willmake the rubbing compound cutquicker, but will also leave gouges, pits,scratches, and swirl marks, and willproduce heat. If using the power buffer,keep the buffing pad wet with material.Do not allow the pad to dry out.Gradually lighten up on pressure as ahigh gloss appears. Several applicationsmay be necessary. If the pad dries out,coarser particles scratch rather than cut.After a rubbing compound has beenused, apply a ‘glaze,’ then wax the part.

4) Waxes—There are a number of waxes onthe market. Try to use one specificallydesigned for fiberglass. Apply a thin coat ofwax. Do not leave a large residue becauseexcess wax can yellow, causing a streakingpattern later.

General instructions on waxes:

a) Read the directions on the can.

b) Do not use in direct sunlight.

c) Use clean cloths.

d) Work a small area (about 3 feet by 3feet) at a time.

Normally, the harder the wax in the can, thehigher the wax content. Softer waxes have ahigher proportion of silicones and solvents inthem. If a power buffer is used, use a lowRPM with light pressure. Keep it moving atall times to prevent heat build-up.

Waxes formulated specifically for gelcoat/fiberglass surfaces are handled bymany boat dealers, shower stall dealers,and automotive retail stores.

5) Sealants—While sealants may provide a wetluster or slick surface when applied to a newor sanded and/or compounded/exposed gelcoat surface, CCP has not found them tosignificantly extend the gloss or colorretention life of that surface. If appliedfrequently during the use of the FRP item, asealant will make the surface look betterduring that use; however, a one timeapplication will not protect or add durabilityto the gloss or color of the surface. Waxesdesigned for exterior surfaces performsimilar benefits as sealants. One systemmay last longer than another beforereapplication is needed to achieve a slickfeel and luster. Again, neither has beenfound to be a one-time application solutionto weathering.

6) Stains—Many fiberglass parts, as they ageand are used, eventually pick up stains.These stains can come from dust, dirtaccumulation, road tar, plant sap and pollen,rust from fittings, material that has leakedfrom caulking or sealing compounds, covers,other fittings, and accessory parts.



Page 7 of 15


Part Maintenance/Stains continued:

Materials that stain gel coat can be brokendown into two very general type substances:soluble and nonsoluble in water. Themajority will be water soluble. Stains can bedifficult to remove. It requires a lot of trialand error to determine the fastest andeasiest method to remove the stain. Thebest practice is to begin with the easiestmethod and then work up to the morecomplicated. Before trying to remove stains,materials used should be pretested in aninconspicuous area. Some materials notonly remove the stain, but also deterioratethe gel coat or change its color.

The majority of stains will be caused bywater-soluble materials. Prewet the areaand wash with a mild detergent. Beginningwith a small portion of the stain, apply thecleaner, making sure it is no more than afine abrasive as it will also remove some ofthe surface. It may be necessary to comeback with rubbing compound and wax torestore the luster. If the soap and watersolution does not remove the stains, asolvent might be necessary.

Water insoluble materials are often organic-based substances. There are two generalclasses. One is called aliphatic, and theother is aromatic. It is a general rule inchemistry that ‘like dissolves like.’ Beforeusing any solvent, read directions and thewarning label.

CAUTION: If using cleaning solvents,contact must be limited. Leaving asolvent-soaked rag on the part can causedeterioration of the gel coat. Also, manysolvents are flammable.

The accepted procedure is to apply a smallamount of solvent to the area that is beingcleaned, and then promptly wipe it dry.Repeat if necessary, but do not soak anarea. Different types of solvents can beused; test areas are recommended.

The most common removers for aliphatics

are acetone, methyl ethyl ketone (NOTCATALYST, which is methyl ethyl ketoneperoxide), ethyl acetate, and rubbingalcohol. Acetone is a principal ingredient infingernail polish remover and is also found inlacquer thinners. Lacquer thinners alsocontain some alcohols and other solvents.To remove aromatics, try xylene or toluene.These are commonly used as paint thinners.If these materials do not remove the stains,or if the stain has gone deeper into thematerial, then surface abrasion will benecessary. In mild cases, rubbing compoundworks for a small spot. If this does notremove the stain, then use 400 to 600 gritsandpaper, followed by rubbing compound,glaze, then waxing.

7) Scratches and Nicks—Scratches can occurwith normal use. To repair scratches, try thesimplest method first. Work on a small areaof the surface (as small as possible). Firsttry a little rubbing compound. This may notcompletely remove the scratch, but maymake it hardly noticeable. If rubbingcompound does not do a satisfactory job,move on to wet sandpaper. Again, boththese procedures must be followed bywaxing to retrieve the original sheen.

If the scratch has penetrated the gel coat, arepair will have to be done. For instructionson repairs, see Section 6 on Patching in thischapter or contact the manufacturer of thepart. Minor repairs can be done easily withthe knowledge of how to work withpolyesters. A good repair is almost invisible.Major repairs should be done by aprofessional.

In cases where there is extensive damage, itmay be necessary to paint or refinish thefiberglass part. In all cases, read thecoatings manufacturer’s literature anddirections on the container.Recommendations should be read andfollowed. Two-component polyester oracrylic urethanes find best acceptance.



Page 8 of 15


Part Maintenance continued

8) Shrink wrap—Boat manufacturers, marinas,and dealers are being encouraged to‘shrink-wrap’ boats by those who sell thewrap and heat guns. This practice issuggested to keep boats clean duringstorage and transit. As a manufacturer of gelcoats for the marine and fiberglass industry,CCP believes it is important to alert ourcustomers to the complications and risksassociated with this practice.

Of course, a clean boat is preferable to adirty boat. However, those who choose toshrink-wrap boats need to consider thepossible adverse side effects as well asviable alternatives.

CCP’s concern centers on two primaryissues:

• Heat applied to the laminate• Moisture trapped next to the gel coat

Shrink wrapping involves heat being appliedagainst a plastic film. The heat causes areaction and the film ‘shrinks to fit.’ Thisheat—if/when applied to a laminate—canhave an adverse effect. Heat can bringabout fiber print and postcure distortion.

These wraps may not ‘breathe.’ If thesefilms trap water or condensed moisture nextto the gel coat surface for prolongedperiods, the possibility of blistering or colorfading is likely. Boats are obviouslyconstructed to sit in water. However, lakes,rivers, oceans, etc., have moderatetemperatures compared to heat trappedinside plastic. It is somewhat analogous torolling up the windows of a car on a hot day;it is hotter in the car with the sun beatingthrough the window than on the outside. Thelength of time and the temperature at whichthe FRP article is stored with the plasticwrap, as well as the color of the gel coat andthe shrink wrap, are major factorsinfluencing the severity of this possibleproblem.

Breathable materials which would allow

moisture to escape are preferred. Less heatis preferred to more heat, and no heat is thebest option when covering a fiberglass part.

If it is the customer’s decision to continuethe shrink wrap practice with the fullknowledge of the risk involved, then CCPencourages adoption of certain techniqueswhich can reduce the severity of thesepotential problems:

a) Use white or light-colored shrink wrapfor less heat generation.

b) Taping of shrink wrap to rails or to thewhite or off-white gel coat surface or anarea not affected by the moisture willplace the condensed moisture in anarea less sensitive to these problems.

c) Seal or tape the shrink wrap to a f thehull in such a way that collectedmoisture does not rest against an areathat is highly visible.

d) Place a barrier of foam or fabricbetween the plastic film tape and the gelcoat surface to prevent heat-releasedplasticizers from reacting with the gelcoat surface.

Removal of the discoloration depends onseverity. Mild cases have been removed to alimited extent by use of a heat gun. Theprocedures must be conducted cautiously and atlower heat settings to avoid heat discoloration aswell as laminate print.

D. Proactive Minimization—Now that the causesof weathering have been addressed, the nextquestion is: What can be done to minimize theseeffects of weathering?

Here is a simple, 10-step procedure that has shownto positively influence the problem of weathering:

1) Keep the molds in good condition.

a) Do not let polystyrene, wax, or dirtaccumulate on them, and pay particularattention to radii and nonskid areas.

b) Do not clean molds with styrene.



Page 9 of 15


Proactive Minimization continued:

2) Choose a gel coat optimized for durabilityand application.

3) Choose colors with weathering in mind.

4) Do not thin gel coats.

5) Contact the gel coat manufacturer beforeadding anything (except catalyst) to the gelcoat.

6) Calibrate the gel coat equipment.

7) Use the proper type and amount of catalystwith complete mixing.

8) Keep film thickness as uniform as possibleand not excessively thick.

9) Clean and wax the finished part at leasttwice per year.

10) Ship a ‘care package’ of instructions with themanufactured part.

5. WEATHERING TESTS—The principalenvironmental elements causing the deterioration of gelcoat include light energy, heat, and moisture. The onlyway to evaluate the weathering characteristics of a gelcoat is to test it.

A. Outdoor Exposure—The best test is outdoorexposure. The ideal location should have lots of sun,moisture, and warm temperature, (e.g., southernFlorida). The only problem is time; usually it takesone year or more to achieve results.

Several configurations for outdoor testing arecurrently in operation, primarily in Florida. Testoptions include open or closed back sample. Thetest panels are placed at 5, 26, or 45 degrees facingsouth. The panel angle affects the amount of UVradiation striking the surface. Integrated energytaken from Florida readings is presented in the chartthat follows at the top of next column:

VARIATION IN RADIATION WITH PANEL ANGLE

Panel Angle Total

Radiation

* (MJ/M2)

UV Radiation

* (MJ/M2)

5 degreeS 6453 300

26 degrees 6480 271

45 degrees 6458 260

* Mega joules per meter2

B. Artificial Weathering—The brief chronologythat follows details the significant milestones inartificial weathering technology:

• 1918—first enclosed carbon arc (used to testfabrics for the Navy)—Atlas Electric.

• 1930s—introduction of the source for the openflame Sunshine carbon arc.

• Late 1950s—first xenon arc source—Heraus(Atlas quickly followed).

• 1968—the 6500 W xenon power sourcecurrently in use became available; aquartz/borosilicate filter combination was widelyused by the automotive industry.

• 1970—FS40 fluorescent bulb (B bulb)weatherometer introduced.

• 1984—the 313 B fluorescent bulb, a morepowerful version of the FS40 bulb is introduced.

• 1987—the 340 A fluorescent bulb is introduced;more realistic UV cut-on frequency.

• 1980s-90s—enhanced filter technology toprovide better spectral simulation of sunlight(xenon units); feedback/data acquisitiontechnology to control the irradiance intensity (allunits).



Page 10 of 15


Artificial Weathering continued:

There are two fundamental issues which must beconsidered when selecting an acceleratedweathering method. These two issues, which mustbe considered in sequence, are:

Correlation and Acceleration. The term correlationrefers to the ability of the accelerated test to produceresults which agree with real-time outdoor testresults. Acceleration is a measure of how rapidly thetest can be conducted using an acceleratedweathering device compared with outdoorweathering. If agreement exists with outdoor results,it is valid to estimate the acceleration of thelaboratory test.

The single most significant component of simulatedweather is the nature of the light (radiation). Lightenergy varies in intensity throughout the ultraviolet,visible, and infrared components of the spectrum.The most energetic, and therefore most damaging,portion of the spectrum is the ultraviolet region, withwavelength less than 400 nanometer (nm). Theultraviolet portion of the spectrum has been furtherdivided by ASTM (G113) into three regions, UV-A,UV-B, and UV-C.

The UV-A region consists of wavelengths (400-315nm); this type of light causes polymer damage. TheUV-A light will transmit through window glass and istherefore relevant to interior materials. The nextsection of the ultraviolet region is the UV-B whichconsists of wavelengths (315-280 nm). UV-B light ishighly energetic and will result in polymerdeterioration. UV-B light is the shortest wavelengthlight reaching the Earth’s surface. UV light is filteredby common window glass and is therefore relevantfor components used outdoors. The most energeticsection of the ultraviolet region is UV-C light(wavelength below 280 nm). This region of the solarultraviolet spectrum is filtered by the atmosphereand is found only in outer space.

Testing protocols have been established by severalstandards organizations, including ASTM (AmericanSociety for Testing and Materials), SAE (Society ofAutomotive Engineers, ISO (InternationalOrganization for Standardization), as well as othergroups (DIN, GM, AATCC, FLTM, NSF, VW, Ford,Renault).

The four basic options to accelerated weathering ofexterior materials are:

1) Light source based on electrified xenon gas(modified via optical filters)

2) Light source based on the arc producedbetween carbon rods (filtered)

3) Light produced by fluorescent bulbs

4) Sunlight concentrated using a Fresnel(outdoor) reflector

C. Weathering Instruments

1) Xenon Arc Weatherometer—The xenonlamps are the closest match to solar powerdistribution throughout the UV/visible/IRspectrum. The Ci65 xenon unit fitted with aquartz inner filter and borosilicate outer filterhas been the industry standard. Recently,data has been published comparing otherfilter combinations. The borosilicateinner/borosilicate outer filter combinationhas been shown to provide highercorrelation with Florida exposure resultsthan the quartz/borosilicate combination.

The Xenon exposure is based on kilojoulesof energy per meter area (kJ/m2). CCP’sunit yields 200 kJ/m2 per week. A 1400kJ/m2 test (equal to about one year southFlorida exposure) will take seven weeks torun. This method of expressing exposure(kJ/m2)) allows for accurate comparison ofone test series to another. Measurements injust ‘hours’ do not compensate for variationin lamp intensity as the bulb ages.

2) Carbon Arc Weatherometer—Graphing ofthe spectral power distribution for the carbonarc weatherometer shows the Sunshinecarbon arc to be an improvement over theolder enclosed carbon arc. The spectral cut-on (appreciable energy) frequency of theSunshine unit approximates sunlight near300 nm. Neither the Sunshine nor enclosedcarbon arc provides a good representationof sunlight over the entire UV/visiblespectrum.



Page 11 of 15


Weathering Instruments continued:

3) Fluorescent Bulb Unit (QUV or UVCON)—The older FS40 B bulb and the UVA-313bulb produce significant irradiance in the UVlight region. These bulbs are particularlyharmful to aromatic unsaturated polyesterwhich have light sensitivity in the spectralregion emitted. The UVA-340 bulb has apeak irradiance wavelength which is muchcloser to sunlight. The UVA-351 bulb isintended for testing interior materials. Thefluorescent bulbs do not contain significantlevels of infrared radiation, which isresponsible for the different temperaturereached by different colored panels insunlight.

4) Fresnel Reflector—Fresnel-type reflectors—such as the EMMAQUA (DSETLaboratories) and SUN10 (Atlas ElectricDevices)—use multiple flat mirrors toconcentrate the sunlight onto samplesmounted on a target plane. The radiant lightconcentration varies with wavelength, but isapproximately equal to ‘eight suns.’ An airblower is used to control the specimensurface temperature.

The Atlas Ci65 weatherometer (Type ’S’boro-silicate/borosilicate inner and outerfilters) consistently produces relatively highcorrelation with Florida exposure over arange of colors and appearancecharacteristics. The EMMAQUA deviceprovides good overall correlation for glossretention, but it does not fare quite as well atcorrelating with Florida on some importantcolor change characteristics. The smallerxenon unit (DSET CPS) and the carbon arcweatherometer perform similarly, showinghigh correlation in some respects and lowcorrelation in others. The UVA-313 bulbconsistently exhibits poor gloss and overallcolor change correlation with the Floridadata set. The UVA-340 bulb produces asignificant improvement in correlation at theexpense of time (acceleration factor ofapproximately 3). Issues of correlation and

acceleration must be consideredsequentially.

The Atlas Ci65 xenon arc weatherometerand the EMMAQUA+NTW device providedthe highest level of correlation with highacceleration. The UVA-340 bulb unitrepresents a significant improvement incorrelation over the UVA-313 bulb althoughthe test is significantly slower than the Ci65or the EMMAQUA+NTW. Significantdifferences exist in purchase price,operational cost, and capacity among theweathering devices.

Features of Weathering Devices

Device Light Source Moisture Max. Temp.

QUV B

313 bulb

Unrealistic—

UV below that of

sun

Dew cycle 60ºC

QUV A 340 UV component only Dew cycle 60ºC

Carbon Arc UV/Visible—

poor match

Water

spray

63ºC

DSET CPS

Xenon

UV/Visible—

good match

None 44ºC

Atlas Ci65

Xenon

UV/Visible—

excellent match

Water

spray

70ºC

EMMAQUA

+

*NTW

Magnification

of sunlight

Water

spray

—

*Night Time Wetting—



Page 12 of 15


D. Methods to Assess a Material’s Response toWeather—The traditional methods to monitordeterioration due to weathering focus on thechanges in appearance. The gloss meter and colorcomputer form the basis to evaluate appearancechanges. The gloss meter measures the specularreflection (shine) of the gel coat on a scale of zero to100 (zero = dull and 100 = perfect reflection). Thecolor computer quantifies the color-related changessuch as yellowing, fading, and milkiness of the gelcoat. The Wave Scan unit can measure long- andshort-range surface attributes such as fiber print orsurface distortion. The haze meter measures haze(light diffusion) rather than gloss.

Changes in appearance of the gel coat duringexposure include gradual reduction in gloss as wellas potential change in color. When the part isdemolded the gloss will register in the high 80s tolow 90s depending on the gloss of the mold surface.The part continues to be visually acceptable until thegloss reaches a value at or below 50. As the glossvalue continues to drop, the surface appearsincreasingly dull, and eventually chalking is evident.Changes in color of the gel coat are highly systemdependent, being influenced by initial color. Lightcolors (white, off-white) are generally evaluated foryellowing or overall color change. Medium anddarker colors are frequently evaluated for fading oroverall color change. The surface may have moreprint-through and distortion as well as a haze.

1) Gloss Change—Gloss is determined bymeasuring the amount of specular light reflectedfrom a surface. Typically, the measurements aretaken at 20, 60 and/or 85 degree angles from thelight source. The 20 degree and 60 degree anglesshow the most change and the 85 degree angle theleast.

2) Color—Reference the Instrumentation andDetermination sections in the chapter on Color.NOTE: As the degree of gloss drops during theweathering process, the gloss influence on colormeasurement will increase.

3) Surface Profile—The Wave Scan canmeasure print-through and distortion. It measureslong-term as well as short-term waviness. Long-termwaviness typically can still be seen at distances ofup to 6 to 10 feet. Short-term waviness is mostobvious at a close distance of about 20 inches.

4) Haze—Diffusely scattered light (haze) canbe caused by long- and short-term waviness.Surfaces that exhibit haze will have a sharp reflectedsurface that is surrounded by a halo. Formeasurement with the Byk-Gardner haze-glossreflectometer, two additional apertures are used oneither side of the 20 degree aperture, which allowsfor the measurement of the diffusely scattered light.

6. ADDITIONAL READING—For a complete review ofgel coat weathering correlation, ask a CCPrepresentative for a copy of ‘Evaluating the Durability ofGel Coats Using Outdoor and Accelerated WeatheringTechniques: A Correlation Study,’ L. Scott Crump, CookComposites and Polymers Co., ReinforcedPlastics/Composites Institute SPI, 51st AnnualConference, 1996.



Page 13 of 15




Page 14 of 15







Page 15 of 15

OPEN MOLDING: Field Service—Cracking



In This Chapter1. Overview of Gel Coat Cracking

2. In-Plant Sources of Gel Coat Cracking

3. Post- Production Sources of Gel Coat

Cracking

1. OVERVIEW OF GEL COAT CRACKING—A gelcoat acts as a thin (less than 30/1000 of an inch)cosmetic shell to protect the composite and add color tofiberglass parts. However, gel coats are not designed tocontribute any structure to a fiberglass part. In designinglaminates, the mechanical strength of the gel coat isusually not included in the composites strengthcalculation.

NOTE: Gel coat cracks are always caused by movementdue to stresses upon the laminate. The sources andreasons for gel coat cracking are complex and caninvolve every element of a fiberglass part’s life cycle,from design to production to usage. An analysis of someof the typical sources for these stresses on fiberglassparts can be helpful in determining the root causes of gelcoat cracking.

During the life of a fiberglass part, cracking can occur intwo places:

• In-Plant: The fabrication or production of the partcan introduce cracks in a variety of ways thatinvolve the composite materials, and/or stressesthat involve the handling of the parts.

• Post-Production: The end-use or finaldestination of a fiberglass composite part canintroduce stresses that might exceed the designand production quality of the parts.

2. IN-PLANT SOURCES OF GEL COATCRACKING—Possible sources and contributing factorsfor gel coat cracking that can occur during typicalproduction of fiberglass parts are:

A. Gel Coat Thickness—Over-application of gelcoat is the number one reason for gel coat cracking.

Gel coats, like all coatings, are designed to be usedin a narrow range of thicknesses. If the gel coat isapplied too thin, the part could have cure andcoverage issues. If the gel coat is applied too thick,yellowing or cracking could occur.

B. Demolding—The process of demolding afiberglass part can generate, in most parts, greaterstresses than the part will encounter throughout therest of its life cycle.

C. Handling Before Assembly—A fiberglass partwithout its structural support elements (ribs,stiffeners, etc.) is extremely fragile. Even smallmishaps in handling these parts can stress thelaminate beyond its design parameters and therebyinitiate cracks that may not appear until later in thepart’s life.

D. Design of the Part—The design of a fiberglasspart is critical to the short-term and long-termdurability of any gel-coated part. Marginal designsthat do not consider the range of possible stressesare likely to produce cracks.

E. Complex Part Geometry—While fiberglassfabrication does offer the versatility to combine manycomplicated shapes into one larger part, there arepractical limits to these unitized designs. Complexpart shapes are more difficult for gel coat application(deep draws are hard to gel coat with a consistentthickness), for lamination layout and especially fordemold.

F. Cure/Green Strength—Undercure at the pointof demold of any of the polymeric materials in afiberglass composite can lead to cracking. Themechanical strength of a fiberglass composite buildswith time as the thermoset polymers in the resins,gel coats, cores, and putties cure. If the cure isslowed either by low temperatures or incorrectcatalyst levels, or if the part is demolded too quickly,cracking can occur because the ‘green strength’ ofthe part is not sufficient to protect the part fromstresses at demold.



Page 1 of 4

OPEN MOLDING: Field Service—CrackingCopyright 2008

G. Glass Content—The fiberglass adds thestiffness to a composite part. Cracks can occur if theglass content is too low, too high or inconsistent, orif the glass reinforcements are oriented incorrectly.

H. Joining/Fitting Parts/Pinning Boat Decks—Fitting fiberglass parts together is a great source ofstress on the laminate. While composite parts willflex to some degree to allow for fitting and joining,stresses will be built into the parts that may laterproduce cracks in relieving the stresses.

I. Metallic Pins of Screws—Use of metallic pinsor screws to join fiberglass parts can also be asource of cracking due to differences in thermalexpansion coefficient between the metallic materialand the composite. Drilling and countersinking pilotholes can significantly reduce cracking at fastenerlocations.

J. Jigging Stresses—Using jigs while bondingstructural elements such as ribs and stiffeners candeform fiberglass parts beyond their designed limits.Cracking can arise from placing the part in the jigs orfrom shrinkage during the cure of the adhesives orputties.

K. Voids in Laminate—Voids left in the laminatecan cause cracking by allowing parts of the laminateto move more than the designed limits or by causingseparations in the laminate cross-section.

L. Temperature—The temperatures that fiberglassparts are exposed to can lead to cracking duringprocessing. Temperature not only affects the cure ofthe laminate but low temperatures can alsocontribute to cracking in ‘fully’ cured parts. Thestiffness of fiberglass parts increases as thetemperature decreases. Uneven heating or cold-shock can also cause cracking in FRP structures.

3. POST-PRODUCTION SOURCES OF GEL COATCRACKING—Among factors that affect gel coatcracking after parts are assembled and have left theproduction plant are:

A. Handling During Shipping—Proper cradlingand use of supports are critical when transporting alltypes of fiberglass composite products. It is relativelyeasy to over-stress a composite part during shipping(i.e., boat hulls are designed to be supported bywater on all sides, not by two fork lift tongues, andstorage tanks are designed to carry a static load, notswing from a crane, etc.).

B. Misuse in Final Application—Unintendedusage, misuse, and abuse are often the sources forcracking once the fiberglass part is put in service.

C. Environmental—Temperature extremes andother weather-related issues are often determined tobe causes for gel coat cracking.

D. Design Flaws—Repeated cracking in the samearea on multiple copies of a composite part might bean indication of either a laminate constructiondeficiency or a design flaw that is concentratingstresses in that area. Parts can also be under-engineered for stresses in ‘normal’ usage, leading togel coat cracking.



Page 2 of 4

OPEN MOLDING: Field Service—CrackingCopyright 2008



Page 3 of 4







Page 4 of 4

OPENMOLDING:FieldService—SwimmingPoolRecommendations




2. Material Selection

3. Application

4. Owner Maintenance

1. INTRODUCTION—The look, feel, durability, andstrength of fiberglass makes this unique material anideal candidate for the construction of swimming pools.With proper selection of materials, good workmanship bythe manufacturer, and reasonable maintenance by theconsumer, a fiberglass unit will provide many years oftrouble-free service; however, if these criteria—materialselection, workmanship, and maintenance —are notmet, problems affecting the appearance of the fiberglassunit can be encountered. In fact, problems such asblistering, staining, and color fading can occur after aunit has been placed in service for only a short period oftime.

2. MATERIAL SELECTION—Swimming pools areexposed to continuous water contact of 50 to 100ºF.This factor, coupled with the use of a variety ofchemicals in the treatment of pool water, provides forsevere operating conditions. It is important to select theproper materials for these demanding applications.

To reduce and minimize potential problems, CCP hasformulated specific gel coats for making pools.

A. Specific Products—These products are listedbelow. All are MACT compliant for the swimming poolindustry.

960-LK-171SW Medium Blue960-WK-433 White960-LF-214SW Light ‘Baby’ Blue960-W-016SW White

B. Swimming Pools Only—These products arenot recommended for spas or saunas or anyapplication where the composites will be exposed tocontinuous moisture contact in excess of 100ºF.

These products also should not be used for anyother MACT-compliant application.

CAUTION: Do not use any other products for apool without consulting a CCP representative.

CCP does not recommend or sell any materials forrepair or refinishing of swimming pools to the post-coating markets.

Each of the materials used in constructing afiberglass unit has an influence on the performanceof the finished product. This includes the laminatingresin, reinforcement glass, gel coat, and catalyst.The manufacturer should carefully select allmaterials and then test the entire system by asuitable test method.

One such test method is the 100 hour boiling watertest per ANSI Z124.

A major concern in regard to proper materialselection should be the avoidance of gel coatblistering. Blistering is a severe cosmetic problemwhich is expensive to repair. It can also lead toanother problem unique to pools. That problem iscalled Black Plague.

Black Plague is a black or brown staining of the gelcoat surface and will form around a blistered area.Chemically, the source of Black Plague appears tobe a reaction of the cobalt accelerator found in allroom-temperature-cured polyester and the chlorinecompounds used in treating pool water.

To prevent Black Plague, eliminating blistering isessential (see Section 5 in this chapter on Blistersand Boil Tests). Blistering is best minimized by usingISO/NPG gel coats, vinyl ester barrier coats, andisophthalic or vinyl ester laminating resins. The gelcoat must be applied to at least 20 mils wet filmthickness, and good spray procedures should befollowed.

Glass selection must also be carefully considered.Because of the wide variety of reinforcement glassavailable (i.e., the glass type, sizings, and bindersused), a specific recommendation is not given here.



Page 1 of 4

OPEN MOLDING: Field Service—Swimming Pool RecommendationsCopyright 2008

MATERIAL SELECTION continued:Generally, a chopped glass laminate is superior to amat laminate. Some surfacing veils can be used toimprove a mat laminate’s resistance to blistering.However, not all surfacing veils and glass mats (oreven rovings) will give the same blisteringresistance. Therefore, the manufacturer isencouraged to test the complete resin, glass, gelcoat, and catalyst system before enteringproduction.

3. APPLICATION—Proper application is necessary forgood field performance of the finished unit. Even if thebest materials are used, poor application techniques canresult in an inferior unit. One important manufacturingconcern is proper catalyzation. Improper catalyzationcan lead to poor gloss, blistering, and color fading.

The picture on the next page shows color change ona panel that was made in the field and then exposedin CCP’s lab.

A: Control—no exposureB: Exposed in water at room temperatureC: Exposed in water at room temperature that

contained pool chemicalsD: Exposed in warm water that contained pool

chemicals

The white splotches are caused by excess catalystor catalyst drops from poorly atomized catalyst. Poorcatalyst/gel coat tip alignment also can cause this,which will be evidenced by a ‘spray’ pattern in thegel coat surface.

Gel coat color fading in particular can be extreme ifthe unit is exposed to unusual chemical treatment by

the owner. Some color fading of the gel coat surfaceis expected over a period of time. Also, certaincolors are more inclined to fading than others. Thecolor fade is usually slow and not to a degree whichis objectionable to the unit owner.

However, this fade can be accelerated to the point ofbeing objectionable when any two of three factorsexist. These factors are:

• Overcatalyzation of the gel coat duringapplication

• Excessive use of chlorine compounds inwater treatments

• Elevated temperatures

If all three factors are present, the fade willoccur most rapidly.

Excessive use of chlorine compounds in watertreatment can attack the gel coat even if it has beenproperly applied. But the discoloration will beincreased if good manufacturing techniques areignored.

Overcatalyzation is known to accelerate the gel coatcolor fading. The manufacturer can encounter unitswhich have faded in spots, patches, or even stripes.These are usually symptoms of overcatalyzation.

4. OWNER MAINTENANCE—Owner care of the unit isthe least controllable factor in assuring good fieldperformance, and yet mistreatment by the owner may bethe source of many field failures. A variety of chemicalsare used in pool water treatment and in marine cleaning.When used in excess (especially the chlorinecompounds or acid cleaners), color fade can result.

The unit manufacturer should select gel coat colorswhich are resistant to fading in a chlorine environment. Itis important to remember that chlorine is a bleachingagent and that no pigmentation system is completelyresistant to chemical attack.

The unit manufacturer should offer recommendations forwater treatment. Those guidelines listed on poolchemical containers quite often are standard forconcrete pool construction and may not be applicable tofiberglass units.

Many conditions can influence the performance of FRPpools. Evaluation of all components together is the keyto successfully servicing the finished article.



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OPEN MOLDING: Field Service—Swimming Pool RecommendationsCopyright 2008



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Page 4 of 4

OPEN MOLDING: Field Service—Blisters and Boil Tests


Part Four, Chapter VII.5

Copyright 2008


2. Causes of Blistering

3. Boil Tests

4. Troubleshooting Blisters

1. INTRODUCTION—In the manufacture of fiberglassparts, sooner or later blisters occur.

A blister is a raised surface area behind which there iseither a hollow area (generally referred to as an airbubble) or a liquid area (swelling). Blisters normallyappear on the surface of the part. They are very seldomcaused by the gel coat.

An analogy may be seen in the condition of an old car.Generally, rusted areas around which the paint hasblistered will be noted. Many of these blisters are notdue to the paint failing, but rather to rusting of the metal.

When looking for the source of blisters, it is important toconsider not only the gel coat, but all the ingredients thatmake up the total composite.

2. CAUSES OF BLISTERING

A. Air Pockets—Air trapped beneath gel coat cancause a blister to form when the surface is heatedenough to cause the entrapped air to expand. A partin sunlight can reach temperatures greater than150°F. The darker the color of the part, the higherthe temperature. If the surface above the air void isweaker than the force generated by expansion, ablister will form. These voids can also serve as acollecting point for liquids, such as water orresidues.

An air pocket is a common cause of blistering andcan be easily located by tapping the part with aplastic or wooden stick. Air voids generally areindicated by a difference in sound; usually thatsound will be dead or muffled. Air pockets such as

these are generally detected and repaired in theplant. They will vary in size and are more commonlyfound in radii (corners).

Most of these air pockets are caused by poor rollout,too much glass and/or filler, or poor wetout of theglass or glass springback. Some air pockets arecaused by debris that has fallen into a mold,trapping air or affecting bonding between layers dueto contamination. These voids, however they areformed, will also cause the gel coat to crack moreeasily.

B. Entrapped Liquids—Entrapped liquids areanother common cause of blisters. An entrappedliquid can expand with heat. Heat can cause somematerials to form gas or to become areactive/corrosive liquid. These blisters will normallyshow up a few hours after the part is pulled andplaced in the sun. Some will take longer to appear.Bubbles of entrapped liquids are generally randomand about the size of a quarter or smaller. Ifpunctured, they are sticky and contain fluid.

Any non-reacted liquid, such as catalyst, can be self-sealing or encapsulated. The outer edge of the dropwill react with the polyester to form a tight gelled skinthat entraps the rest of the unreacted catalyst. Thecatalyst can cause a blister by simple expansion, orby breaking down to form gasses and/or solvent-likematerial that slowly weakens the surrounding area.

An entrapped solvent can also expand, change intoa gas, and then weaken the area around it.

Uncatalyzed resin entrapped between cured layerscan cause blisters. Some of the more commonentrapped liquids and their characteristics are foundin the table on the chart below.

C. Attack by Chemical—This type of problemoccurs when a corrosive agent literally breaks up thepart from the outside or from within.

When polyesters are attacked by a chemical, thefirst signs are swelling and blisters.



Page 1 of 6

OPEN MOLDING: Field Service—Blisters and Boil TestsCopyright 2008

Attack by Chemical continued:

The general types of materials than can break uppolyesters are: alkaline (such as lye, caustic,trisodium phosphate); certain solvents (such asacetone, ethyl acetate, or methyl ethyl ketone, if incontact long enough before evaporation);chlorinated liquids (such as methylene chloride).Typically, these solvents will also causedelamination of the gel coat.

If chemical attack is suspected, it is important tocheck for signs of attack on metal fittings, trim, andwood attachments. This agent can be airborne fromwater sources.

D. Creation of an Osmotic Pressure Cell—Osmosis is a very common natural phenomenon.This mechanism involves a membrane and liquids orliquid mixtures that can or cannot pass through thatmembrane. In the case of laminates, the gel coatacts as a membrane. Water permeates through thegel coat to saturate it, but also to saturate thelaminate behind it. The hydrolysis of the laminatingresin (i.e., the depolymerization of the unsaturatedpolyester polymer) generates decomposingmolecules. Those molecules are dissolved in thewater, saturating the laminate and the osmoticpressure cell created. Indeed, on one side of the gelcoat (i.e., the membrane) is water, and on the otherside is a blend of water and decomposition productsthat are too large to pass through the gel coat. Whenthe pressure created becomes higher than thecritical stresses the materials can withstand (e.g.,when the water attack of the laminating resin hasbeen extensive and the concentration ofdecomposition products has become very high), thestructure weakens and blisters are formed.

The blister resistance is therefore affected by all theparameters that affect the overall hydrolyticstabilities (i.e., the chemical resistance to water) ofthe components (gel coat, laminating resin), and thestrength of each of the components in the laminate(geometry, degree of cure) as well as the presenceof impurities such as unreacted species (unreactedcatalyst, synergist, etc.).

The ability of a laminate to resist osmotic blisteringcan be greatly improved through the use of vinylester barrier coats or skin laminates. Of course, thedegree of improvement is dependent on the quality

of the materials and the application techniques used.A vinyl ester barrier coat or skin laminate isrecommended for fiberglass parts that will beexposed to continuous moisture, such as boat hulls,swimming pools, waterslides, etc.

3. BOIL TESTS (ANSI WATER RESISTANCETEST)—The boil test consists of exposing the gel-coated surface of a laminate to 100°C water for 100hours. Caution must be taken when interpreting theresults of this test.

This test is one section of the ANSI-Z124 standard forfiberglass plastic bathtub units. It was developed to setup a material standard for showers and tubs. The ratingapplies to five separate areas:

• Blister (size and number)• Change in surface profile (fiber prominence)• Cracks• Loss of visible gloss• Color change

The rating scale for each area is subjective. The scale is‘zero to five’ with ‘zero’ being no change and ‘five’ beingthe maximum change possible.

Values one, two, three, and four are increasinggradations of change. A panel is independently rated bythree experienced people. A panel is failed if any onearea has a rating of four or over, or the total of all areaaverages is over nine. The ANSI standard also lowersthe severity of the test for thermoplastic sheet materialby lowering the test temperature to 82°C. It is importantto note that blisters do not necessarily mean failure bythemselves; rather, it is the combination of all factors.

The question has been posed as to whether the boil testcan be related to actual use. Several factors haveinstigated such questioning:

• Different test temperatures are used for differentmaterials.

• The thickness of gel coat and type of substrateis not specified, but both are major influences onthe success or failure of the specimen.

• Test conditions are extremely severe and arenot found in normal field application.

• Some materials which fail this test have beenused successfully for years in certain fieldapplications.

• Test results are very dependent on types ofglass and resin and their application.



Page 2 of 6


BOIL TESTS (ANSI WATER RESISTANCE TESTcontinued:

However, it is important to remember that in theproduction of shower stalls, which must meet FHArequirements, these criteria must be met, as well as theother requirements listed in ANSI-Z124.

This test, if performed with proper controls, can behelpful in choosing or comparing materials.

Since the boil test is required by the shower stall industryand is referred to by other segments of the FRP industry,a good understanding of what affects this test is a must.

The purpose of the boil test is to create conditions thatwill accelerate the attack of the water and thereforeobtain results much quicker than at room temperature.

The following factors will affect the performance of gelcoats on boil tests:

A. Type of Resin Used in the Gel Coat—Themore resistance the gel coat has to the attack ofwater and to permitting the water to pass through it,the better the test results. In general, gel coatsystems rank as follows:

1) Orthophthalic systems (fair)2) ORTHO/NPG systems (fair to good)3) Straight isophthalic systems (good)4) ISO/NPG systems (best)

B. Water Resistance of Other Gel CoatComponents

C. Cure of the Gel Coat—If the gel coat isundercured, it will have poorer water resistance.Major factors affecting cure are:

1) Temperature—If parts are made below 60°F(16ºC), poor cure will result.

2) Percent catalyst—If the catalyst is too low ortoo high, undercure can occur. Too highappears to be a greater problem than toolow because excess catalyst remains thatcan act as an osmotic agent. It cansimultaneously chemically attack the gelcoat and weaken it further.

3) Type and grade of catalyst—Differentbrands and types of catalyst will havedifferent ratios of ingredients and producedifferent cures.

4) Thickness—If a gel coat is less than 12 mils,the possibility of undercure is increased due

to insufficient mass and to excessive styreneloss due to surface evaporation. NOTE: Athin film (or overspray) sprayed onto curedgel coat will cause water blisters. Areas thatreceive extended water immersion (boathulls, swimming pools) should not bebacksprayed with a thin film/overspray ontocured gel coat.

5) Contaminants—These consist of agentssuch as water, solvent, and intentionally orunintentionally introduced materials.

D. Thickness of Gel Coat—The thicker the gelcoat, the better the results will be. This is because athicker gel coat can withstand a higher pressure andslows water penetration.

E. Barrier Coat—Use of a properly applied vinylester barrier coat such as CCP’s ArmorGuard

®will

reduce blistering (see Part Four, Open Molding,Chapter IV.)

F. Quality of the Laminating Resin—In general,orthophthalic resin yields poorer results thanisophthalic resin or vinyl esters.

G. Fillers—Certain fillers can increase or decreaseblistering and color change.

H. Laminate Cure—The cure of the laminate isimportant because it is more susceptible to attack ifunder-cured (see ‘C’ for factors involved).

I. Type and Sizing of Glass (Layer Next to GelCoat)

1) A layer of surfacing veil yields good resultswhen used as a skin coat for either choppedglass or mat.

2) Cloth yields better results than mat orchopped glass. NOTE: Layers of cloth nextto each other show sporadic large blistersdue to poor bonding between layers.

3) Roving (chopped laminate), in general,yields better results than chopped mat.NOTE: There is a difference between typesand brands of roving. Some yield poorerresults than mat, others better. This may berelated to the type of glass binder andsizing.

4) Mat is generally a worse choice than anyother type of fiberglass due to binder deposits.



Page 3 of 6


J. Lay-up Time—The more time that passesbeyond lay-up readiness, the poorer the boil/blisterresistance will be due to weaker bonding betweengel coat and laminate.

Clearly, there are many factors that affect the boiltest. If this test is used to compare gel coats or othermaterials used in making a part, it is important tomake sure that nothing else overrides the materialbeing tested. For example, in comparing two gelcoats, the following should occur:

1) Proper fabricating temperature should bemaintained above 60°F (16ºC), preferably77°F (25ºC). Maintain proper cure.

2) Proper amount and type of catalyst shouldbe used. Refer to the data sheet on eachproduct.

3) Uniform thickness is desirable. Strive for anormal film thickness (18 mils ± 2) and ahigher film thickness (25 to 30 mils). Side-by-side draw-down comparison is mostaccurate.

Use the same gel coat, laminating resin, glass andamount of proper catalyst consistently throughout allsystems to be compared, allowing for only one variableat a time.

4. TROUBLESHOOTING BLISTERS—When blistersare encountered, do not assume a particular cause. Dothe following:

A. Examine the Blistered Part

1) Where does the blister occur on the part?2) What is the number of blisters, and what is

the size of each blister?3) Were water and/or heat involved?4) How soon did the blister develop after

demold?

B. Puncture and Observe the Blister—Makecross-section cut and note the following:

1) How deep is the blister, or where did it occur(gel coat, skin coat, bulk laminate, orbetween layers)?

2) Does it contain fluid, or is it dry?3) Does it have a different color?4) Does it have an odor? NOTE: Decomposed

catalyst will not smell like pure catalyst.5) Is there any discoloration around or near the

blister on wood or fittings? What color is thediscoloration?

C. Selection of Most Probable BlisterMechanism—Select the most probable mechanismand list materials, equipment and procedures thatare involved.

Now comes the hard part: Try to determine whatmaterial, process, or combination caused the blister.Sometimes the cause will be obvious. In otherinstances, testing will be required.

It is impossible to guarantee that even one of theparts will never develop blisters. Too manymaterials, types of equipment, and people areinvolved. However, CCP can provide guidance onthe best methods to reduce the occurrence ofblisters. These strategies are:

• Apply proper types of gel coat; refer to datasheets. NOTE: Some gel coats, such asorthophthalics and some ORTHO/NPG’s,develop blisters within themselves thatcause failure regardless of laminateconstruction.

• Apply the proper type of gel coat. CCP’sisophthalic or ISO/NPG gel coats arerecommended.

• Use proper equipment and procedures toapply; refer to the Equipment Selectionsection. If catalyst injection equipment isused, make sure it is properly calibrated.

• Make sure temperature is above 60°F.• Avoid contamination in any part of the

system.• Use a high-quality laminating resin.• Use the right catalyst and its proper amount

in all polymer portions of the composites.See data sheets.

• Assure that the laminate is applied andcured properly, especially the skin coat.

• Choose a suitable glass; refer to the datasheet on that glass.



Page 4 of 6



Page 5 of 6







Page 6 of 6

Composites

Applications Guide

OPEN MOLDING: Field Service—Patching

Part Four, Chapter VII.6

Copyright 2008

In This Chapter

1. Introduction

2. General Working Conditions

3. Minor Surface Repairs—Spot Patching

4. Area Patching—Spray Patching

5. Holes or Cracks in the Gel Coat that Require a

Putty Patch

6. Patching of Holes, Punctures, and Breaks

7. Finishing Techniques

8. Helpful Hints

9. Troubleshooting Guide

10.Associated Data

11.Wall Chart Patching Guide

1. INTRODUCTION—This section of the manual

is designed as a guide for the repair of a fiberglass

part.

No matter how much care is taken in making

fiberglass parts, some parts will require repair. The

need for repair may be prompted by: defects in the

mold, operator error, contamination, rough

demolding, impacts during handling, storage, or

use.

The first step to take when a defect is found is to

try to determine the cause. If possible, steps

should be taken to correct the cause, then work

should proceed to repair the part.

2. GENERAL WORKING CONDITIONS—

Fiberglass repairs should be made with the same

type of gel coat and/or laminating resin used to

make the original part. The same chemical

reactions that gel and cure the materials used to

make the original part take place during repair.

Considerations of safety, temperature, catalyst

levels, and calibration to make a good part are also

important to achieve a good repair. In fact, they

are more critical since additional heat from other

steps is not available, and the repair does not set

up for hours in the mold until sanded and buffed.

A. Safety—Many of the materials used in

fiberglass repairs can be hazardous. Therefore,

before any repairs are started, obtain and read

all MSDSes on ALL materials (gel coats, resin,

catalysts, solvents, etc.). Make sure all safety

requirements are met before proceeding.

B. Cure

1) Temperature—Repairs should not be

attempted when material, ambient, or substrate

temperature is below 60°F (16ºC) as poor cure

may result. Poor cure can cause the repair to

change color, be dull, and/or prematurely fail.

Note that at 60°F (16ºC), repairs will be slow and

will have long cure times.

It is best to have temperatures above 75°F

(25ºC) since small masses of materials (thin

films of gel coat) are being used. Air and part

temperatures are critical as cold air, or draft, and

cold parts will greatly influence small masses of

materials. If this happens, poor cure can result.

2) Catalyst—Since small amounts of gel coats

are used and additional heat from the laminate is

not available, the catalyst levels should be kept

on the high side, normally 2 percent but no more

than 3 percent. Refer to CCP product data sheets

for catalyst recommendations.

To achieve good cure, the ratio of catalyst to

material should be calibrated (measured) to be

within proper limits.

Many repairs are small and require small

amounts of patching materials.

Cure continued:



Page 1 of 13

OPEN MOLDING: Field Service—PatchingCopyright 2008

One method of catalyzing is to use the drop

method (Example: for a 2 percent catalyst level for

a teaspoon of gel coat, add 4 to 6 drops of

catalyst). This method can work, but the margin of

error is great because of the small amounts used.

A better method is to use larger amounts (50

grams at a minimum) and measure material and

catalyst using grams. Even if 95 percent of

catalyzed material is discarded, it is cheaper than

redoing a repair due to error in using small

amounts of materials. It is less costly in the long

run if the materials are accurately measured.

The next best method is to measure by volume (50

ml or cc of gel coat, 1 ml or cc of catalyst).

Low-cost measuring devices can be purchased from

scientific apparatus suppliers, or from

laboratory/hospital supply firms (see Yellow Pages)

or local pharmacies. (Also see J under Helpful

Hints.)

C. Visibility—Most repairs are done on areas that

are visible. It is necessary that the repair area be

well-lighted to ensure the defect is removed, to see

what is being done, and to make sure the repair is

acceptable.

D. Mixing—To assure uniformity, all materials

must be mixed before use.

NOTE: Material used in repair is taken from larger

production containers. The larger container must

be mixed before repair supplies are obtained.

3. MINOR SURFACE REPAIRS—SPOT PATCHING—

The following procedure is recommended for small

areas which have damage to the gel coat only, or

which have a blemish (hole, gouge, or scratch)

that is deep enough to penetrate through the gel

coat to the

fiberglass, but not deep enough to go completely

through the laminate (less than 1/32 inch or 30

mils deep).

A. Roughen up the surface of the damaged area

using a hand-held router, power drill with burr bit

attachment, or coarse sandpaper. Feather the

edge surrounding the blemish with finer grit

sandpaper. Do not undercut this edge.

B. Be sure that the area to be patched is clean

and dry, and free of wax, oil, or other

contaminants. Solvents (see Warning G under

Helpful Hints in this chapter) such as ethyl

acetate and methyl ethyl ketone are suitable for

this purpose.

C. Measure out 50 grams, ml or cc of gel coat in

a suitable container such as an 8 ounce cup. By

adding 5 percent (2.5 g, ml, or cc) 970-C-940

Wax Solution to the gel coat, good surface cure

can be obtained without other coverings.

NOTE: Always make the patch with material from

the same batch of gel coat that was used to

make the original part. Failure to comply with

this rule will almost certainly result in an off-color

patch. (See K under Section 8, Helpful Hints.)

Thoroughly mix the proper amount of MEK

Peroxide into the mix. The addition of 2 percent

(one g, ml, or cc) catalyst to mix should yield a

gel time of about that of the gel coat itself.

D. Work the catalyzed gel coat into the damaged

area with a knife or spatula. Slightly overfill the

blemish, including the area around and above, to

allow for shrinkage. Puncture and eliminate any

air bubbles that may be trapped within the gel

coat.

E. If wax solution is not added to the gel coat,

cover the repaired area with cellophane, waxed

paper, or parting film (PVA) while the patch

cures. NOTE: PVA can be difficult to spray, but in

order for it to provide an efficient barrier, it must

be sprayed as a film rather than a dust coat; but

do not flood it on or spray it too thickly.



Page 2 of 13


F. The patch should be allowed to cure thoroughly

before any further action is taken; cure time should

be approximately two to three hours. The patch

has not cured sufficiently if a thumbnail leaves an

impression in the gel coat.

G. Sand the patched area with 220 grit wet or dry

sandpaper. Change to 320 or 400 grit, then to 600

grit wet or dry paper. If the patch shrinks to a

point where the surface is not level with the

adjoining areas, repeat the preceding process.

Complete the finishing process by buffing with

rubbing compound to a smooth surface. Then wax

and buff the surface to a high gloss. (See Section 7

in this chapter on Finishing Techniques.)

If this spot patch does not match the part in color,

double-check to see if the same batch of gel coat

was used in the patch as was used for the original

part. It might be necessary to make a spray patch

(see following directions) over this spot patch or

over an entire section. As with bodywork on

automobiles, it is sometimes necessary to spray

patch an entire section at a time, using edges or

corners as boundaries for difficult-to-match

situations.

4. AREA PATCHING—SPRAY PATCHING

A. Sand the area to be patched using 220 grit

sand paper. Feather the edges, using finer grit

paper in hard-to-match situations.

B. Clean the surface with a suitable solvent as

described under Item B in Section 3 on Minor

Surface Repairs—Spot Patching.

C. Always make the patch with material from the

same batch that was used to make the original

part. Not using the same batch will almost certainly

result in an off-color patch. (See K under Section

8, Helpful Hints.)

For best color match and weathering

considerations, the best method is to use the

material as is with no diluents or additions except

catalyst. CCP, however, offers several products

as aids for reducing the viscosity for better spray

characteristics and leveling (less orange peel),

and/or for accelerating patch cure time for

quicker sanding. See individual data sheets on

each of the following for mixing and application

instructions:

1) 970-X-900, Fast PATCHAID® for reducing

viscosity and when repairs need to be sanded

quickly. Typically, the patch can be sanded in 45

minutes depending on catalyst, temperatures and

air movement.

2) 970-X-901, Slow PATCHAID® is used to lower

the viscosity and when repairs do not need to be

sanded quickly, such as mold resurfacing and

when initial gel times are already very short.

Also, 970-X-901 is formulated to yield better

dilution; therefore, it works better when using

aerosol cans or air brushes.

3) 970-XJ-037 is a fast PATCHAID® version of

970-X-901.

4) Ten percent of a 2 percent wax solution also

can be used as a diluent. Typically, the patch can

be sanded approximately two hours after

catalyzation.

CCP does not recommend solvents (acetone,

MEK, ethyl acetate, or any of the replacement

solvents or cleaners) for diluting gel coat. If they

are used, it is important to remember: do not use

a replacement solvent or cleaner.

Solvents are more flammable and reduce the

flash point of the gel coat. Always use high purity

solvents.

Use high atomization and do not spray too close

to the part, or too quickly; do not apply too

thickly.

Retained solvent in the patch will deteriorate

patch quality by retarding cure, creating porosity,

changing the



Page 3 of 13


AREA PATCHING—SPRAY PATCHING continued:

color, lowering gloss, reducing hardness, and

compromising weatherability.

D. Using a Binks 115 type spray gun, spray the

catalyzed gel coat over the entire sanded and

feathered area. Thickness should be approximately

8 to 12 mils for good cure. If spraying an area

where gel coat has been completely removed,

thickness must be at least 12 mils for good hide.

E. Let the patch cure thoroughly.

F. Sand the patched area with 400 grit wet or dry

sandpaper; then change to 600 grit wet or dry

paper. Buff with rubbing compound, then wax and

buff to a high gloss for the final finish. See Section

7 on Finishing Techniques, and the Spray Patching

Wall Chart in this chapter.

5. HOLES OR CRACKS IN THE GEL COAT THAT

REQUIRE A PUTTY PATCH—There are two aspects

to putty patching. If only a ‘thick’ gel coat is

required, use about 2 percent fumed silica. If a

reinforcing or strengthening putty is required, use

1.0 percent fumed silica and about 10 percent of a

glass filler such as milled fibers, micro glass, or

glass bubbles. Reinforcing putty should be used to

resist patch cracking if the laminate is weak or

flexible.

Preparation and procedure are the same as those

given for minor surface repairs. Normally, spray

patches have to follow a putty patch because air

bubbles are entrapped in the patch or there is a

slight color change due to the filler added.

Coarse sandpaper, such as 100 grit, can be used to

level the putty patch. Masking tape can be placed

alongside the patch to keep from sanding the

surrounding gel coat.

Finish with a spray patch.

6. PATCHING OF HOLES, PUNCTURES, AND

BREAKS—The following repair method is used for

damage which penetrates completely through or

deeply into the entire laminate.

A. Repairs from the inside

1) Prepare the affected area by cutting away the

fractured portion of the laminate to the sound

part of the laminate. A keyhole or saber saw

works well to cut away these ragged edges.

2) Roughen up the inside edges of the affected

area, using a power grinder. Feather out the

backside at least half the diameter of the hole to

be patched.

3) Clean the surface and remove all paint or

foreign substances as previously described in

spot patching.

4) Use a template to give ‘shape’ to the part.

Tape cellophane in place over a piece of

cardboard (or aluminum) large enough to

completely cover the affected areas with the

cellophane toward the inside of the part.

Aluminum is used when contour is present.

5) Cut glass fabric and mat to the shape and

size of the hole. Cut another set of reinforcement

material one-half diameter larger than the hole.

Materials and total thickness of each set should

approximate that of the part being repaired.

6) Thoroughly mix an ample amount of resin

(approximately 1 pint per square foot) and

catalyst (6.5 gm, ml, or cc). Using the hole-sized

set of reinforcement, daub catalyzed

Repairs from the inside continued:

resin onto the glass mat to

thoroughly wet it out. Wet out the fabric in a

similar manner. Apply the mat against the

surface inside the hole. Then apply the fabric.

7) Roll out or squeegee out all air bubbles. Allow

the area to cure well. Build this laminate up to

the same thickness or greater than the thickness

of the original laminate.

8) Apply catalyzed resin and the larger

reinforcement over the hole patch and the



Page 4 of 13


surrounding surface.

9) After the laminate has cured, remove the

cellophane and backing from the outside of the

hole. Rough up this surface from outside,

feathering the edge with a power grinder.

10)Now follow procedures 3.A. through 3.F.

B. Repairs from the outside

1) If it is not possible to access the backside (blind

hole) of the part, a template will not be used. Cut a

piece of cardboard slightly larger than the hole.

Then cut the fiberglass mat and cloth along the

same outline as the cardboard insert, only slightly

larger. Thread a wire or wires through the center of

the cardboard insert; follow with the fiberglass.

2) Roughen up the inside edges of the hole to at

least half the diameter of the hole. If a power

grinder cannot be used, thoroughly sand by hand

with coarse sandpaper.

3) Wet out the fiberglass with catalyzed resin.

Force the plug through the hole. (Don’t worry

about neatness; the first concern is a structurally

sound repair.) Use the wire to pull back and secure

the plug until the resin cures. When cured, check

adhesion of the plug and proceed.

4) Mask the area with tape and paper to protect

the surrounding surface. Then, if a large void is

present, repeat Steps A.6 and A.7. Smaller voids

could be patched with putty material.

5) Using 80 grit sandpaper, smooth and blend the

surface to be coated into the surrounding surface.

6) Follow Steps A through F in Section 4 on Area

Patching—Spray Patching to complete the patch

and to obtain a high gloss color matching patch.

7. FINISHING TECHNIQUES—The frequency of

complaints related to cosmetic finish problems has

increased dramatically in the last several years.

These defects are most often referred to as pits or

comet tails. It is highly likely that increased

customer demand for contact molded FRP parts

accounts for these problems. This problem is not

exclusive to Cook Composites and Polymers gel

coats; it is industrywide. CCP’s research staff has

observed such problems at one time or another

on all products in the field or in lab testing.

Production process techniques have changed to

help manufacturers keep up with increased

customer

FINISHING TECHNIQUES continued:

demands. To meet production demands, molds

are sometimes run in poor condition and turned

more

quickly. This, in turn, causes more sanding and

buffing to remove mold defects on production

parts caused by overuse.

Parts are not allowed to sit in the mold as long as

previously and are not well-cured when sanded

and buffed, which worsens problems. Dual-action

sanders are replacing hand sanding. These

sanders are fast, but the sanding area is a

minimum of 4 inches regardless of the size of the

defect. Polishing is accomplished with 10 inch

buffers, which further increases the size of the

finish area. Finishers often stop sanding with 320

grit DA paper and use high-speed electric buffers

along with

coarse buffing compound to take out the

scratches. High RPMs (more than 3000) and

excessive buffing pressure can cause excessive

heat build-up. Buffing should not heat the gel

coat to a level greater than ‘just warm.’

Intense finishing of the gel coat creates comet

tails, burns the gel coat, and causes the resin to

postcure, producing print-through. Higher RPM

buffers, in conjunction with heavy pressure, can

definitely induce finishing problems. Sanding to

the finest possible grit is highly recommended so

that the least amount of buffing is required.

A. Review safety procedures for using DAs and



Page 5 of 13


power buffers. Be aware that these tools can ‘kick

out’ and spin off particles.

B. Determine if sanding is necessary to smooth

out the defect or patch. If not needed, go to Step

F.

C. Start sanding with 400 grit sandpaper. When

finished, wipe off sanding dust and any loose grit.

NOTE: If a coarser type paper is necessary to

speed sanding the area, work step-by-step back up

to 400 grit. Follow each grit by wiping off to

remove any loose grit. Example: 220 paper was

necessary, wipe off; 320, wipe off; 400, wipe off.

TIP: If a paper coarser than 400 is constantly

required, review patching techniques to minimize

orange peel and/or surface roughness. For quick,

better, and more economical patches, do the least

amount of work to get a good repair.

D. Wet sand with 600 wet/dry paper.

E. Wash off (using water) all loose dust and grit.

F. Start buffing using a wool pad with a medium

grit rubbing compound. CCP has found that either

3M™ Super Duty #05954 or #06025 quickly

removes 600 scratches with the least amount of

buffing and residual haze. Use this type of

compound or its equivalent. Ideal buffing speeds

are from 1700 RPM to 3000 RPM.

1) Always precondition a new/clean pad by pre-

buffing with compound at low RPMs in order to

‘wet’ the fibers of the pad.

2) Do not use excessive buffing pressure. Let the

weight of the buffer do the work.

3) Use plenty of compound to lubricate and cool

the gel coat surface. As the compound begins to

dry out, lighten up on the buffer.

4) ‘Spur’ the buffing pad when it starts to glaze

over or change to a new preconditioned pad.

5) Always keep the pad tilted just slightly to the

surface being buffed. Do not tilt the buffer so only

the pad edge is being used.

6) Wipe or wash off all loose compound and grit.

7) Gel coats may leave some ‘coloring’ on the

buffing pad. This is a function of the pigment

used, and is not an indication of the degree of

cure.

G. Using a separate, pre-wet synthetic pad, buff

with a fine finishing glaze such as 3M™ Finesse-It

II (#05928) or equivalent.

H. Thoroughly wipe the area to remove all traces

of finishing glaze and residue.

I. Wax using a light-stable, exterior-protective

paste wax.

8. HELPFUL HINTS

A. To speed up the patching process and for

patching in cold working conditions, use heat

lamps, heat guns, or space heaters or prebuff

before sanding. CAUTION: Overheating may

cause blistering and poor color matching.

Patching materials are flammable; be careful.

B. Spray patches generally match better than

spot or putty patches.

Spray patches continued:

C. Different colors behave differently in

patching.

D. Additional additives to the gel coat may cause

a color change.

E. As a general rule, keep any patch as small as

possible.

F. If the patch is not cured thoroughly on the

surface, wiping with a suitable, fast-evaporating

solvent will clean the surface sufficiently to allow

sanding without clogging the paper.

G. WARNING: Acetone and many other fast-

evaporating solvents are highly flammable and

can be toxic. Consult suppliers, individual

MSDSes, and literature such as the book,

Dangerous Properties of Industrial Materials,



Page 6 of 13


published by Reinhold Publishing Corporation, New

York, for physical hazards of these materials.

H. Check technical literature for the correct

catalyst levels on all materials used.

I. Do not use excessive buffing pressure.

Excessive pressure creates heat; this heat may

cause print-through and distortion. This heat and

pressure can actually abrade the cured film of gel

coat away down to the laminate.

J. CCP’s experience has shown that one of the

biggest factors that contributes to patching

problems is lack of a method for measuring gel

coat, PATCHAID® and catalyst. The method CCP

has developed for mixing patching material in the

shop is quick, accurate, and inexpensive. The effort

required to accurately measure gel coat,

PATCHAID® and catalyst is often the difference

between a patch matching or having to start over

again.

1) Apply mold release in three or five ounce cups

to be used for molds. NOTE: Do not use paraffin-

lined cups. The paraffin can be scraped loose

during mixing and contaminate the batch.

2) Obtain samples of gel coat to make castings.

Use a 70:30 ratio. Catalyze enough gel coat to

make two castings. Catalyze gel coat at 0.5

percent so that castings are less likely to get too

hot and crack. Weigh catalyzed gel coat into waxed

cups, and set on a level surface to cure.

If using five ounce cups, a 100 gram standard

patch mix will allow plenty of room for mixing. Use

100 grams in one cup and 70 grams in the other.

Allow the castings to cure and cool, then remove

from the cups.

When preparing to make a patch, use the castings

to mark lines in the mix cup. Gel coat should be

filled to the bottom line, then PATCHAID®

to the top line. Stir PATCHAID® and gel coat

together thoroughly and then catalyze at two

percent for

best cure. A 10 cc graduated

cylinder should be used to measure catalyst. For

a 100 gram mix, use two cc’s of catalyst.

K. Tinting—At times, tinting in the field is

required, such as for a part which was made

several years ago and must be patched, or on a

one-time small job. Tinting is a talent that

requires experience to do it well and quickly. CCP

normally does not recommend tinting in the field,

but for those who must, here are a few rules to

follow:

1) If the part is weathered, buff out the area to

be patched to achieve the real color.

2) Use only pigment concentrates designed for

polyester.

3) Tint at least one-half gallon of gel coat at a

time. The smaller the batch, the harder it is to

tint.

4) Make small additions (adds), mixing well and

scraping down the sides of the container between

adds. Subsequent adds should get smaller as the

color is approached.

5) Sometimes it is helpful to test each

concentrate with 50 percent white gel coat before

hand, because it is easier to see shades.

6) Get the basic color shade first (yellow, blue)

then look for the minor differences, such as

reddish, greenish, etc.

7) If the color match is not close, put a wet spot

of the batch on the solid part or next to the wet

sample. As the true color approaches, it will be

necessary to go to catalyzed sprayouts be-cause

some colors change from wet to cured.

8) Once color match is reached, record what

pigments and amounts were used to get the color

in case it has to be matched again.

The first chart on the next page shows the



Page 7 of 13


approximate effects of adding the particular

pigment concentrates.

NOTE: Use only pigment concentrates designed

for polyesters.

Colorant Primary Color Secondary Color

White Lighter Chalky in dark colors

Black Darker Gray in pastels

Green Green Darker

Blue Blue Darker

Red Red Darker, pink in pastels

Gold Yellow Yellow Red

9. TROUBLESHOOTING GUIDE

PROBLEM ITEM TO CHECK

Color does not

match

Wrong batch used for patching; fillers added; too many accelerators added;

catalyst level off; patch undercured; trapped solvent; dirty spray gun; buffer

developed too much heat.

Patch is dull Undercured; catalyst level off; low temperature; sanding too quickly; trapped

solvent; PVA sprayed too wet.

Comet tails Too coarse a sandpaper used on last sanding; buffing too hard; dry pad.

Low gloss Excessive buffing pressure; coarse compound.

Sand marks Too coarse a sandpaper used in last step—work up through 600 wet.

Ring around patch

(halo)

Edge not feathered; not sanded properly; porosity in original gel coat, may

have to overspray; undercured patch; improper level of PATCHAID®.

Crack reappears Crack was not fully ground out; weak laminate.

Patch is glossy, Original gel coat undercured; buffer developed too much heat; too much



Page 8 of 13


part dull PATCHAID®.

Porosity or void in

patch

Not sprayed or leveled properly; filler not mixed in properly; trapped solvent;

air not worked out.

Patch is depressed/

shallow

Patch will shrink—allow for this by overfilling. Do not sand and finish until patch

is cured. ‘Hot’ buffing can cause patch to shrink. Condition patch by prebuffing

before sanding.

10. ASSOCIATED DATA—See Chapter III.2 Specialty Gel Coats—Metalflake, and CCP’s PATCHAID®

Data Sheet DS-70D.



Page 9 of 13


11.WALL CHART PATCHING GUIDE

SPRAY PATCHING GUIDE

Average gel coat

weight per gallon is

10 pounds.

There are 128 fluid ounces

in a gallon.

At 10 pounds per gallon each fluid

ounce would have a weight of

approximately 35 grams.

One cc/ml of catalyst is equal to 1.1

grams (for shop use, one gram per

cc/ml acceptable).

For best color match, always use

the same batch of gel coat the part

was made from.

Use recommended level of

PATCHAID® to reduce the gel coat

for spray patching.

These patching materials are

formulated to:

#1—Help the patch

spray smooth.

#2—Speed cure of the patch. #3—Surface cure the patches for

ease of sanding.

For each color, establish a level of

patching additive that gives the

best patching results.

Usually 30% PATCHAID®

works well.

Make a master mix of gel coat and

PATCHAID® for patchers to use.

The idea here is if the mix works

for one patch, it should work for

all,



Page 10 of 13


if catalyzed with

the proper amount of catalyst.

Important: The gel coat patching

mix must be mixed thoroughly

prior to each use.

Use 2% of approved 9.0% Active

Oxygen catalyst.

Three fl oz of gel

coat patching mix

= 35 g; use 0.5

g/cc/ml to

catalyze

Two fl oz of gel

coat patching mix

= 70 g;

use 1.5 g/cc/ml to

catalyze

Three fl oz of gel coat

patching mix = 105 g;

use two g/cc/ml to

catalyze

Four fl oz of gel coat patching

mix = 140 g;

use three g/cc/ml to catalyze

NOTE: g/cc/ml are rounded to nearest .5 g/cc/ml



Page 11 of 13




Page 12 of 13







Page 13 of 13

LOW VOLUME CLOSED MOLDING: Introduction


Part Five, Chapter ICopyright 2008

In Part FiveChapter I: Introduction

Chapter II: Materials

Chapter III: Preform Constructions

Chapter IV: Process Features and Variations

Chapter V: Converting from Open Molding

Closed molding is a broad category of fabricationprocesses in which the composite part is produced in amold cavity formed by the joining of two or more toolpieces.

Examples of closed molding processes include matchedmetal die molding of SMC and/or BMC, RTM, VARTM,and vacuum infusion. These processes are generallyregarded as higher technology than open-moldprocesses because they require more planning, andoften, more sophisticated and costly equipment. They dooffer a number of significant advantages over openmolding, including higher production rates, reducedlabor, two-sided finish, greater design latitude, andreduced emission of Hazardous Air Pollutants (HAP).Consequently, the interest and usage of closed moldingprocesses is beginning to increase from its current levelof about 10 percent of today’s UPR market.

Increased awareness of environmental impact on thepart of composite fabricators, combined withgovernmental regulatory pressures, has led to the studyand control of two aspects of composites fabrication.First, fabricators are concerned with the rate of HAPemissions. Second, there is concern with the absolutelevel of overall HAP emitted, which is determined byboth the rate of emissions and the production volume.Closed molding processes can be used to reduceemissions as well as increase production relative toopen molding.

There are many variations of the closed moldingprocess, each having a unique or distinctive aspect. Forthe purposes of this technical discussion, thesevariations are categorized into two types: Resin TransferMolding and Compression Molding.

• Resin Transfer Molding (RTM)—Resin TransferMolding (RTM) processes are those in whichliquid resin is transferred into a closed cavitymold. The reinforcing fiber, any embeddedcores, and inserts are placed into the cavitybefore the resin is introduced. Over time, anumber of RTM variations have beendeveloped. Common examples areConventional Resin Transfer Molding (CRTM),Vacuum Assisted Resin Transfer Molding(VARTM), and Vacuum Infusion (VI). Figure5/II.1 illustrates schematically some features of atypical RTM process.

• Compression Molding—Compression moldingprocesses use clamping force during moldclosure to flow a pre-manufactured compoundthroughout the mold cavity. The clamping forceis typically delivered to the system by some typeof press. Sheet molding compound (SMC), bulkmolding compound (BMC), and wet moldingcompound are examples of premanufacturedcompounds used in compression molding.



Page 1 of 3

LOW VOLUME CLOSED MOLDING: IntroductionCopyright 2008



Page 2 of 3







Page 3 of 3

LOW VOLUME CLOSED MOLDING: Materials


Part Five, Chapter IICopyright 2008


2. Resins

3. Reinforcement

4. Cores

5. Filler

1. INTRODUCTION—In general, the materials used inResin Transfer Molding processes are the same asthose used in ordinary open molding, with the mostsignificant differences in reinforcement technology. Theprocess production rate determines many of therequirements for materials. Higher production ratesrequire the use of premade reinforcement preforms andresins with short gel and cure times. Lower productionrates use materials that more closely resemble typicalopen mold material systems.

2. RESINS—All varieties of polyester and vinyl esterpolymers are used in the Resin Transfer Moldingprocess. Polymer choice depends on end use. Most areformulated as low viscosity, non-thixotropic resins. Idealviscosities range from 50 to 150 centipoise beforeadding any filler. Cure properties depend strongly oncycle times and can be adjusted either by the resinmanufacturer or by the molder. Adjustments to gel time,cure time, and peak exotherm can be made by addingpromoters, co-promoters, and inhibitors. Theseadjustments are not a trivial matter because they requirevery accurate measurements. In addition, somematerials are toxic. Many molders prefer to buy pre-promoted, ready-to-use resins.

Resin gel times must be long enough for the mold to fillbefore gelation, and short enough to meet productionrate goals. For high production rates of small parts, filltimes are less than a minute, gel times are 2 to 3minutes, and cycle times are less than 15 minutes.Exotherm control is very important for such rapidprocesses in order to maximize mold life. Molds can

have provisions for cooling to remove exotherm heat.For large parts, fill times can approach 45 minutes, withgelation at 90 minutes, and at least overnight cure.

Selection of peroxide initiators depends on theproduction rate. Various MEKP initiators are common. Insome cases, different peroxide initiators are preferred.When a quicker gel and cure is desired, acetyl acetoneperoxide (such as 2,4-pentanedione peroxide) is used.To extend the gel, blends of MEKP and cumenehydroperoxide or blends of acetyl acetone peroxide andcumene hydroperoxide are used.

3. REINFORCEMENT—Glass fiber is a typical type ofreinforcement; it is available by pattern cutting of rollgoods or preform fabrication. A preform is a constructionof glass fiber that has been shaped to fit into the moldcavity. A preform can lower cycle times two ways: first,the preform fabrication time is not a part of cycle time;second, the preform construction is easily placed into themold. Glass forms that are not shaped to fit the moldrequire more care when they are placed in the mold.Preform fabrication can utilize either roving andconventional glass forms or conformable constructions.For a more complete discussion of preform technology,see Chapter III in this part on Preform Constructions.

Figure 5/II.1 - In a typical RTM process, resin is transferred to a

mold cavity that contains dry fiber reinforcement.

In closed molding, continuous filament mat (CFM) isused instead of the chopped strand mat (CSM) that iscommonly used in open molding. CFM will conform to



Page 1 of 4

LOW VOLUME CLOSED MOLDING: MaterialsCopyright 2008

the mold shape more reliably than CSM, which also hasa tendency to tear and wash in the resin flow, leavingunreinforced areas. Special constructions have beendeveloped specifically to improve conformability by usingspecial knits. Other constructions provide a sandwichstyle laminate with a low density core fiber and glassskins on either side.

CFM is a nonwoven mat of continuous fiber thatgenerally contains some binder. CFM is very lofty (muchthicker for the same weight until compressed) comparedto CSM. Weights for this glass form use the units ofounces per square foot (osf). Typical weights are 1.5 osfand 2.0 osf.

REINFORCEMENT continued:Cored glass constructions are available under a varietyof trademark names. They share a common architecturehaving three distinct layers. Outermost skin layers areglass fiber, while the inner layer is a polymer fiber. Thecored construction adds considerably to bendingstiffness without adding the weight of additional glass.This is because the polymer fiber core material is muchless dense than the glass fiber and because bendingstiffness increases greatly with an increase in thickness.Stitched molding mat (SMM), a product of OwensCorning, and Rovicore, a product of Chomarat, areexamples of core mats with skin weights varying from1.5 to 2.0 ounces of glass and from 5 to 7 ounces ofcore.

CSM is generally not used by itself in pressure injectionprocesses. This material is held together with a binderthat is soluble in styrene. When used alone in a pressureinjection process, the material has a tendency to washand leave un-reinforced areas. During mold closure, thematerial also can tear easily. For these reasons, othermats are more frequently selected. CSM is relativelyinexpensive and is added locally to increase glass skinthickness, but generally in combination with CFM orstitched mat (SM).

The weights for this glass form use the units of ouncesper square foot (osf), with typical weights ranging from0.75 osf to 3 osf.

Stitched mat (SM) is a special chopped strand mat thatis produced without any chemical binders. The strandsare held together mechanically with a polymer stitchyarn. This mat is available in weights ranging from 1 to 4osf. This mat is considerably more conformable than

ordinary CSM.

Surfacing veil (SV) is a nonwoven mat of either glass orpolymer fibers. These materials range between 3 milsand 40 mils thick. They provide a resin-rich layeradjacent to the part surface. This improves bothcosmetic appearance and corrosion resistance.Reduced fiber blooming after sanding is another benefit.

4. CORES—There are a variety of reasons for moldingcores into the laminate. Some provide section thickness(therefore bending stiffness) without adding a lot ofweight. Others provide hard points for locating screw orbolt installations. Cores can range from plywood toPolyVinyl Chloride (PVC) foam or urethane foam-filledhoneycomb. There is a large variety of embeddedmaterials in common use. Even strips of metal havebeen sandwiched between fiber layers. Some cores arenot compatible with the liquid injection process becausethey will simply fill up with resin and add too muchweight. One example is open cell honeycomb.

5. FILLER—Some resins are designed for use in filledsystems in which fillers are used to replace some resin,resulting in both cost savings and improved cosmeticappearance. The peak exotherm temperature is alsolowered which, as an added benefit, contributes to longmold life. Calcium carbonate, calcium sulfate andaluminum trihydrate are commonly used. Filler useincreases both the resin viscosity and the finished partweight and commonly varies from 15 percent to 45percent by weight. In general, the filler size is in the 6 to10 micron range to keep the glass pack from filtering thefiller. A nominal 8 micron particle size is commonly used.Finer filler, as low as 3 micron, is also used.



Page 2 of 4

LOW VOLUME CLOSED MOLDING: MaterialsCopyright 2008



Page 3 of 4







Page 4 of 4

LOW VOLUME CLOSED MOLDING: Preform Constructions


Part Five, Chapter IIICopyright 2008


2. Preforming Process Description

3. Characteristics of the Various Binders

1. INTRODUCTION—The preforming process can varyfrom fairly simple to rather complex. Briefly, this processconsists of the manufacture of a reinforcing mat, whichhas the shape of the part to be molded. This processaccommodates molding those parts that have complexshapes, deep draws, and sharp radii, which are noteasily moldable with commercial flat reinforcing mats.Because of the uniform distribution of the fibers, partsmade using preforms generally have higher physicalproperties compared to parts made by other processes.Preforms are traditionally used in the compression wetmolding process but are also very useful in otherprocesses such as cold press molding, RTM (resintransfer molding), SRIM (structural reaction injectionmolding), and Vacuum Infusion (VI).

Preforms are usually made of chopped fiber glass rovingstrands or fiber glass mat reinforcement. However, thereinforcing fibers may be glass, carbon, graphite,aramid, or other polymers. Preforms are made in aseparate step and delivered to the mold as needed,allowing for more efficient use of resources.

Polymeric binders are used during the manufacture ofpreforms. A binder is a bonding resin applied to thereinforcing fibers to hold them in position so that shapesare maintained as needed for even fiber distribution in amold.

Binders are available in various forms, includingaqueous emulsions, aqueous solutions, 100 percentreactive liquids, solvent solutions, and reactive powders.Thermosetting binders usually cure or set up throughpolymerization caused by the action of heat on peroxideinitiators and/or melamine cross-linking agents. Somebinders are designed to cure by UV or visible light

energy. Preferred binders also have reactive sites thatcan form a chemical bond with both the fiberglassreinforcement and the matrix resin, thus producingcomposites with superior mechanical properties.

2. PREFORMING PROCESS DESCRIPTION—Threemain methods are used in making preforms. These are:

• Directed fiber• Thermoformable mat• Conformable reinforcement

Some of the characteristics of each of these three

processes follow:

A. Directed Fiber Preforming—When this methodis employed, chopped fiber roving (along withbinder) is sprayed onto a screen made in the shapeof the part to be molded. A vacuum is drawn fromthe back side of the screen. This holds thefiber/binder in place. The screen, still under vacuum,is then placed in a high-volume, forced-air ovenwhere the water or other carrier solvent(s) areremoved and the binder is cured. Cure/bake cycle isgenerally 350 to 400°F (177 to 209ºC) for one to fiveminutes. With some binders, lower temperatures canbe used; however, if they are aqueous based, lowertemperatures require increased time for waterremoval. Directed fiber preform binders are usuallyin liquid form, but solid powdered binders have alsobeen used.

A variation of this method is the use of a stringbinder. In this variation, some strands of the rovingare precoated with a binder resin that is either a highmelting point thermoplastic, or a thermosetting resinthat is solid at room temperature and cures atelevated temperature. Like the standard directedfiber method just described, the roving is choppedonto a screen, but without the need for a liquidbinder spray. It is then baked as described before. Ina variation of string binder, a thermoplastic strand ischopped along with standard fiber glass roving.When indexed into an oven, it partly melts andadheres to the glass strands it bridges.



Page 1 of 5

LOW VOLUME CLOSED MOLDING: Preform ConstructionsCopyright 2008

Directed Fiber Preforming continued:

Some comments on directed fiber preforming are:

• Best method to obtain uniform glassdistribution and excellent part definition overcomplicated, three-dimensional shapes.

• Molded parts are stronger than those madeby SMC/BMC at the same reinforcementcontent.

• Lowest cost method of preforming.• Poorest in housekeeping requirements.

B. Thermoformable Mat Preforming—With thismethod, a fiber mat is made with or treated with athermoplastic binder. The mat is heated, usually inan oven, and then placed in a cold mold made in theshape of the part. The mat is pressed to conform tothe mold. After cooling, the mat retains the shape ofthe part. Comments on this method are:

• Fewer housekeeping problems compared todirected fiber method.

• Lower energy requirements than directedfiber method.

• Not recommended for making complex,deep draw parts.

• More expensive than directed fiber methodbecause of the higher cost of using mat andbecause of cutting waste of mat.

C. Conformable Reinforcement Preforming—With this method, a mat made of chopped fibers isplaced on the mold. It can be easily made toconform to the shape of the part to be molded. Onecan cut the mat to the general shape of the mold,place it in the mold, and then press on it to conformit to the shape of the mold.

Comments on this method are:

• Relatively clean, easy-to-use method ofglass placement.

• Some mats are more filamentized thanconventional reinforcing mats, restrictingflow through them.

• May result in areas of low/no reinforcementin parts with deep draws.

• Much more expensive than other methods ofpreforming materials.

• Low or no capital investment to makepreforms.

• Good material to add to other preforms toincrease glass content in resin rich areas.

Figure 5/III.1 - Preform by Plenum Chamber Method.

3. CHARACTERISTICS OF THE VARIOUSBINDERS—Each type of binder has its advantages anddisadvantages, and is briefly described in the chart thatfollows.



Page 2 of 5


Binder Characteristics

Binder Type Advantages Disadvantages

Aqueous emulsion

binders

No VOCs

Excellent preform stability

Thermosetting/rapid cure

Good glass compaction with good flow-through

properties

Chemically bonds to matrix resins and to glass

Excellent part moldability

Energy needed to remove water.

Aqueous solution

binders

Low or no VOCs

Thermosetting/rapid cure

Good glass compaction with good flow-through

properties

May contain formaldehyde.

Energy needed to remove water.

May be pH dependent.

100% reactive

powder

Precatalyzed

No VOCs

Fast cycle time

No water/solvent removal

Lower energy required

Housekeeping problems (dusty).

String binder No solvent removal

Fast cure

Lower energy required

Requires very high suction or double screen for

compaction.

Emerging technology; expensive.



Page 3 of 5




Page 4 of 5







Page 5 of 5

LOW VOLUME CLOSED MOLDING: Process Features and Variations

Copyright 2008

Part Five, Chapter IVCopyright 2008

In This Chapter1. Process Features

2. Variations

1. PROCESS FEATURES—To facilitate understandingand communication when discussing the various RTMprocess variations, a process description and namingconvention is presented in this section. All resin transfermolding processes can be characterized by five basicprocess features:

• Resin pressure head• Resin transfer scheme• Upper mold type• Mold clamping method• Mold open-close method

For each of these process features, there are at leastfour variations that are commonly used. These variationsare presented in table form, followed by a basicdescription of each feature variation, examples ofcommonly known variations, and finally, a detaileddescription of each feature.

A. Resin Pressure Head—The first and mostsignificant feature, this is the state of pressureacross the resin from injection point to vent point; itis the driving force that causes the resin to flowthrough and saturate the fiber pack. The resinpressure head is described by first stating thecondition at the injection location and then statingthe condition at the vent location. The variations are:(1) Pressure to Pressure; (2) Pressure toAtmosphere; (3) Pressure to Vacuum; (4)Atmosphere to Vacuum; and (5) Vacuum to VacuumThese scenarios form the basis for the differencesbetween the common definitions for vacuum-assisted resin transfer molding (VARTM), resin

transfer molding (RTM), and vacuum infusionprocessing (VIP) among others.

B. Resin Transfer Scheme—This describes theplumbing pathway used to transfer the resin into thefiber pack. The first pathway arrangement is discreteport injection in which the resin is introduced atspecific points called ports or injectors. The second

pathway arrangement is edge manifold in which achannel along the part edge (or entire perimeter)provides the resin pathway into the fiber pack. Thethird pathway arrangement is an interlaminarmanifold, whereby a layer of high-permeabilitymaterial is placed midway through the laminatethickness. Fourth is a face manifold, in which theresin is introduced below or (usually) above the fiberpack using some form of resin distribution manifold.Often, this resin distribution manifold is nothing morethan ordinary bubble wrap packing material.

C. Upper Mold Type—This describes the materialsand construction used for the mating mold. Theterms ‘upper’ and ‘lower’ are used to describe themold halves, due to the fact that gravity actsvertically, and gravity is most often used to assist inseparating mold halves.

Variations for the upper mold type are: (1) rigidizedlaminate, which is the conventional RTM mold type;(2) shell laminate, which is a thin glass reinforcedlaminate; (3) multi-use, otherwise known as asilicone vacuum bag; and (4) bag film single use,which is a vacuum bag constructed from rolls ofvacuum bag film.

D. Mold Clamping Method—The means forholding mold pieces together. Variations are: (1)vacuum clamps, (2) mechanical clamps; (3)pneumatic clamps; and (4) hydraulic clamps. Thesevariations have a significant impact on cycle timeand each have different cost requirements.

E. Mold Open-Close Method—The method forseparating mold pieces to allow inserting the dryglass and removing the finished part. Variations are:(1) hand lift; (2) mechanical hoist; (3) pneumaticactuators; and (4) hydraulic actuators. Thesevariations also affect the cycle time for molding andhave varying costs.

Resin

Pressure

Head

Resin

Transfer

Scheme

Upper

Mold Type

Mold

Clamping

Method

Mold

Open‑Close

Method

Pressure to

Pressure

Discrete

Port

Rigidized

Laminate

Vacuum

Clamps

Hand Lift



Page 1 of 21

LOW VOLUME CLOSED MOLDING: Process Features and VariationsCopyright 2008

Pressure to

Atmosphere

Edge

Manifold

Shell

Laminate

Mechanical

Clamps

Mechanical

Hoist

Pressure to

Vacuum

Interlami-

nar

Manifold

Silicone

Multi‑Use

Pneumatic

Clamps

Pneumatic

Actuators

Atmosphere

to Vacuum

Face

Manifold

Bag Film,

Single Use

Hydraulic

Clamps

Hydraulic

Actuators

Vacuum to

Vacuum— — — —

2. VARIATIONS

A. Resin Pressure Head—The Resin PressureHead is the state of pressure across the resin fromthe point of injection to the vent location. Thispressure drop causes the resin to flow through thefiber pack. At some point in the mold cavity’sboundary, the resin enters the mold; this location iscalled the injection port. As the mold fills, the resindisplaces the air. This air escapes through a vent;this location is called the vent port. The resinpressure head is the difference in pressure betweenthese two points.

At the injection port, when resin pressure is higherthan normal atmospheric pressure, the injection isunder pressure. When pressure is normalatmospheric, injection is under atmosphericpressure. At the vent port, when pressure is normalatmospheric, venting is to atmospheric pressure.When pressure is lower than normal atmospheric,venting is to vacuum.

The resin pressure head is described by identifyingthe condition at the injection location and thendescribing the condition at the vent location. Asoutlined previously in 1.B., Resin Transfer Scheme,there are five combinations that are used in RTM.

• Pressure to Pressure• Pressure to Atmosphere• Pressure to Vacuum• Atmosphere to Vacuum• Vacuum to Vacuum

Conventional RTM uses Pressure to Atmosphere.VARTM uses Pressure to Vacuum. Vacuum Infusionuses Atmosphere to Vacuum. These are significant

differences that greatly impact the remainder of theprocess features and variables. The followingschematics illustrate the Pressure to Vacuum,Pressure to Atmosphere and Atmosphere toVacuum resin pressure heads.

Figure 5/IV.1 - For the Pressure to Vacuum Head, a pump

supplies the injection part with resin under pressure and a

vacuum is applied to the vent part.

In the Pressure to Vacuum or Atmosphere to

Vacuum or Vacuum to Vacuum processes, the vent

port must be attached to a resin trap of some sort.

Otherwise, the resin will enter the vacuum system

and plug it up.

Figure 5/IV.2 - For the Pressure to Atmosphere Head, a pump

supplies pressurized resin to the injection part and the vent part is

open to the atmosphere.

B. The Resin Transfer Scheme—It is veryimportant to consider the molding process at thevery beginning of part design. The part must bedesigned not only to be the part, but also to be



Page 2 of 21


Figure 5/IV.3 - For the Atmosphere to Vacuum Head, a vacuum

source applied to the vent part draws the resin from an

unpressurized container through the injection port and into the

part.

successfully molded. This is necessary to ensurethat the fiber pack creation and mold fillingprocesses are economically viable.

In all variations of resin transfer molding theobjective is to transfer the resin into the fiber pack.Pressure forces must be generated in some fashionto drive the resin throughout the part. Once there ispressure on the resin, it will flow. The resin willprefer to follow the path of least resistance. Theposition of the resin as it advances into an unfilledarea is called the resin flow front. This flow frontmoves throughout the mold until the mold iscompletely filled. The control and management ofthis resin flow front is at the center of the RTMprocess. The sections that follow discuss flow ingeneral terms and the various types of resin transferschemes.

The Resin Transfer Scheme continued:

1) General Considerations to ControllingFlow—The glass within the mold cavity iscompressed somewhat by the mold. Themore the glass is compressed, the moreresistance there is to resin flowing through it.The less the glass is compressed, the lessresistance there is to resin flowing through it.The ability of the resin to flow through a fiberpack is called its permeability. The easier itis for resin to flow, the more permeable thefiber pack is.

There are two main resin flow situations,diverging flow and converging flow.Diverging flow starts at a point or area andthe resin flow front goes outward until itmeets some boundary condition. One

example of diverging flow is when there isonly one port, Discrete Port Injection. Figure5/IV.4 depicts one type of diverging flowfield.

Converging flow starts at several points oraround the perimeter.

The multiple resin fronts meet (convergeupon) each other. Examples of convergingflow are the Edge Manifold method, whenthe manifold spans either opposite sides or

Figure 5/IV.4 - In diverging flow, resin enters the mold cavity at a

point and flows outward. Here, discrete port injection is used.

the entire perimeter, and Discrete PortInjection when there are two or moreinjection ports. The schematic below depictsone type of converging flow field.



Page 3 of 21


Figure 5/IV.5 - In converging flow, resin enters the

mold cavity at a point and flows to a single point. Here,

an edge manifold supplies resin to th entire perimeter.

If the fiber flow front gets out of control, itgets ahead of itself, and closes upon itself,sealing in a dry spot. To avoid dry spots,one must determine where the resin front isgetting ahead of itself, and then slow it downin these areas or speed it up in other areas.These strategic areas are located byproducing a series of parts with short shotsof resin, so that the parts are filled to varyingdegrees. Like a time-lapse camera, this setof specimens will clearly show where theresin is travelling too quickly and too slowly.

Sometimes a dry spot can be percolated outof the part. This is accomplished by allowing

resin to continue to flow out the vent port.Depending on where the dry spot is inrelation to the vent, a considerable amountof resin may need to be released. If the dryspot occurs in a consistent place, adding avent port at the center of the dry spot will letthe air out and allow the dry spot to fill.

Special cases can be constructed when

there are mixtures of the two types of flow.Generally, this should be avoided bycarefully considering the fill process beforethe upper mold is designed and built. Interms of broad generalizations, divergingflow vents to the perimeter and convergingflow vents in the center of the part. For theconverging flow, the flow fronts probablydon’t converge right at the vent location. So,the vent must be kept open until all the airworks its way out of the part. For thisreason, converging flow may waste moreresin. The amount wasted depends stronglyon the management of the resin flow front.

Special attention must be paid to thedistance that the resin flow front must move.If one path is farther, it will take more time toget there. If there is an open channelpathway, the resin will prefer to follow thatchannel. If the fiber pack is less permeable,the resin flow front will move more quickly. Ifthere is a vent to atmosphere or vacuumdraw to an area, the flow front will tend toflow toward the draw more quickly. Theseare the fundamental principles of resin flowfront management. Trial and error usuallyproduces an arrangement that fills properly.

2) Discrete Port Injection—The resin enters thepart cavity at a specific point called adiscrete port. The injection port is plumbeddirectly into the part cavity. Usually, only oneport is preferred. This method always uses adiverging flow front; any converging flowfronts will seal in a dry spot. It is best to ventat the farthest reaches of the perimeter. Thereinforcement is placed in the mold. Themold halves are closed. Resin is injecteduntil it fills the fiber pack and flows out of thevents. As the resin reaches each vent, that

The Resin Transfer Scheme/Discrete PortInjection continued:

vent tube is sealed off. Once the last vent issealed, the injection tube is sealed off.Aschematic of discrete port injection can befound in Figure 5/IV.4 for an example of adiverging flow field.



Page 4 of 21


3) Edge Manifold Injection—A resin injectionchannel along the part edge characterizesthe Edge Manifold Injection process. Thereinforcement is loaded and the mold halvesclosed. The resin is plumbed to the channelthrough the injection port. Since the channelis an open space, resin prefers to flow downthe channel rather than flowing into the fiberpack. Once the channel fills, if not earlier,flow into the fiber pack begins. When themanifold follows only a small portion of theperimeter, the flow is diverging, and ventingis performed on the far sides of the part.When the manifold runs completely aroundthe perimeter, the flow is converging, andthe vent is positioned at the flow center ofthe part. If the flow fronts do not convergesimultaneously at the vent location, resinflow is continued until any air bubbles worktheir way out. This adds to resin waste. Aschematic of edge manifold injection can befound in Figure 5/IV.5 for an example of aconverging flow field.

4) Face Manifold Injection—The Upper Moldcontains numerous resin channels. This canbe as simple as bubble wrap packingmaterial under a Single-Use vacuum bag oras complex as a Laminate Rigid Upper Moldwith resin channels molded in. The resin isplumbed to these channels through theinjection port. The resin prefers to flow downthe channels rather than flowing into thefiber pack because empty space is morepermeable than a compressed fiber pack.Once the channels are full, the resinsaturates the fiber pack. A peel ply may benecessary on the top of the laminate if theresin ridges that remain on the part due tothe manifold pathways must be removed.Usually, multiple perimeter vents are usedfor the resin. A good perimeter vent isnecessary to vent the air as the fiber pack iswet out.

5) Flow with Rigidized Laminate Upper Mold—For this variation, the mold cavity isdiscretely the same every time the moldsare closed. If one were to add an extra layer

of glass, it would be squeezed down to thesame height as the glass pack with one lesslayer. Since the amount that the glass iscompressed affects its permeability, thisaffects the resin flow front. For this reason, itis very important to have good dimensionalaccuracy in the mold cavity thickness. Largevariations in the cavity can cause the fiberflow front to behave erratically.

Glass compression and the resulting loss ofpermeability may also be used to control theflow front. An extra layer in strategiclocations will slow the front. Similarly, oneless layer will speed the front.

6) Other Features—A visual method ofdetermining when the mold is full involvesusing witness holes. A polyethylene tubethrough a fitting into the mold is often used.When the resin fills the tube, that vent isclosed. This is repeated until all vents areclosed, injection is halted, and the injectiontube is closed. Simple clamps can be usedto pinch the hoses. Bending the hose andsticking the bent end into a large washer isan economical method for sealing the port.When the polyethylene hose does not goentirely through the injector or vent fitting,one must drill out the cured resin before thenext part is made.

Permanently mounted thermocouples canbe used to monitor part exotherm. Thisinformation can be used by the operator todetermine the demold point. Generally, thepart is not removed before the peakexotherm temperature is reached. Thedemold point strongly depends on theproduction rate and the part requirements.Surface profile is compromised by rapiddemold because the part is still curing and

The Resin Transfer Scheme/ OtherFeatures continued:

shrinking. When the resin is curing andshrinking without being in contact with themold surface, the lack of support results inmore fiber print and profile.



Page 5 of 21


Dielectric sensors can be used to monitorresin flow and cure. The simplest dielectricsensors will measure at only one point, suchas a resin trap at a vent location. Thesesensors can provide the signals to close thevent valves automatically, alert the operatorto gelation and indicate the approximate partdemold time. This can greatly reduce thelikelihood for operator error.

When a series of dielectric sensors areused, a computer model displayed on ascreen can show, with color changes, themold fill process and cure event throughoutthe part. Since it can take a bit of time to filla mold, and the resin cure starts atcatalyzation, the computer controller caneven increase the catalyst level slightlytoward the end of the fill process so that theentire part cures more simultaneously. Thiscan decrease the cycle time for large parts.

C. Tooling—For the purposes of this discussion, aclosed mold set contains the following items:

• Lower Mold• Upper Mold

The terms Upper and Lower are used to describethe mold halves. Generally this is because gravityacts vertically, and gravity is most often used toassist in separating mold halves. Although manyprefer to consider molds male or female, manymolds have elements that are in some areas maleand other areas female. In addition, it is possible tohave either one as the upper or lower. Therefore,upper and lower mold halves are the more generaldescription. While there may be more than twophysical tooling pieces, these pieces incorporate allof the following features:

• Part Cavity• Mating Flange• Flange Seal• Injection Port• Vent Port• Alignment Device

The part cavity is the physical space between theupper and lower molds in which the part isproduced. The mating flanges are the portions of the

lower and upper molds which come into contact witheach other when the mold is assembled. The flangeseal (sometimes omitted) is a rubber extrusionplaced in a special recess between the matingflanges. Some compression of the seal rubber isproduced by the mating flanges when the moldpieces are assembled. The injection port is thatlocation in the resin plumbing where the resin entersthe assembled upper and lower mold set. The ventport is that location in the boundary for the partcavity where air escapes when the resin is beingtransferred to the glass pack. The alignment device(sometimes not present, sometimes accomplishedwith the part shape itself) is the mechanism foraligning the upper and lower molds.

Particular requirements for the molds depend largelyupon the pressures that are generated during themolding process. For laminate molds, all of theordinary requirements for open mold polyestertooling apply. There are, however, additionalrequirements for molds that are subject to eitherinjection pressures or large closing forces. Ingeneral, the processes that generate large resinpressures require a robust framing system and ahigh grade polyester or vinyl ester resin and gelcoat. For higher temperature processes, epoxyresins and vinyl ester gel coats are preferred. Uppermolds also have special requirements that are notdescribed in the section on polyester tooling. Thesespecial requirements will be described in thesections that follow.

When Shell Laminate type and Rigidized Laminatetype upper molds are used, special considerationmust be given to orient the pattern to provide a moldparting flange that is both flat and horizontal (or verynearly so). This allows the mold to release from thepart by separating due to a true vertical motion. Ifthe parting flange is not in a single plane, or not veryclose to a single horizontal plane, great difficulties insealing the mold will be encountered during moldclosure. This is because the mold seal rubber is

Tooling continued:

dragged along the nonhorizontal mating flanges asthe flanges come together in a vertical motion. Thiswill most likely result in two things: a leaky mold thatis a housekeeping challenge; and a mold that



Page 6 of 21


produces unfilled parts. Certain rubber sealedextrusions will be more tolerant of nonflat flangegeometries.

Sometimes, the part boundary is extended so thatthe mating flange is more nearly flat and horizontal.The extended portion is trimmed during post-moldfinishing operations.

1) Lower Mold—The Lower Mold constructionfalls into one of the following threecategories:

• Lower Mold Conventional• Lower Mold Conventional with a Wide

Flange• Lower Mold Robust

When the upper mold is the Bag Film,Single-Use mold, the lower mold is aconventional open mold with a conventionalflange. For both the upper mold ShellLaminate and Elastomer Multi-Useprocesses, the lower mold is a conventionalopen mold with a wide flange toaccommodate sealing the upper mold to thelower mold. Flange details will be covered inthe sections that describe the associatedupper molds. The third category, LowerMold Robust, is discussed in the nextsection.

2) Lower Mold Robust—There are a few casesin which the resin pressures areconsiderable. When this is the case, thelower mold must be robust to resist thesepressures without excessive deflection andsubsequent fracture. When the RTMprocess uses pressure to fill the mold andwhen the Upper Mold is a RigidizedLaminate, the lower mold must be robust.This is the conventional RTM mold design.Another case where significant resinpressures are generated is when resin isHand Applied and Hydraulic Clamps closethe mold, causing the resin to flowthroughout the fiber pack. This is theconventional wet mold. (See Part 6 onCompression Molding.)

The flange is typically four to five inches

wide. It must be wide enough toaccommodate both a primary and secondaryseal, as well as resin traps at the locationsof the vents, but narrow enough to resistexcess deflections. The resin traps allowsome amount of air to percolate out after theresin first reaches it and before the ventmust be closed. It is very important to clearlyestablish the filling, venting, alignment, andclamping issues prior to the start oflamination. See associated sections formore information.

The gel coat is either polyester or vinylester; the laminating resin is either a highgrade polyester or a vinyl ester. If apolyester gel coat is used with a vinyl esteror epoxy laminating resin, a specialadhesion coat should be applied. Asurfacing veil, generally 10 mils thick, isplaced in the tooling gel coat when itreaches the tack stage and brush laminatedto a low glass content (10 to 20 percent),while carefully avoiding entrapped air.Entrapped air must be removed and the veilreplaced in a second lamination stage. Theskin coat is typically one layer of 1.5 osfCSM at 35+ weight percent glass. Thelaminate is as much as 12 osf CSM at 35+weight percent glass, laminated two layersof 1.5 osf CSM in each lamination step.

The framing is very robust. The particularframe design depends on the means ofclamping. Individual hydraulic cylinderclamps and mechanical clamps, eitherscrews or toggle style, require the mostrobust frame. This is because clampingforces are localized only at the clamplocation. Mold frames for pneumatic clampsor a hydraulic platen press can besomewhat lighter since the clamping force ismore evenly distributed across the frame.However, these frames must have planar

Tooling/ Lower Mold Robust continued:

and parallel contact surfaces to be usedsuccessfully in a press. If they don’t, thepress forces will crush sections of the mold.



Page 7 of 21


For additional press mold requirements, seethe section on Pneumatic Clamps.

The frame is built about 1/4 to 3/4 inch offsetfrom the mold using two by four, two by two,one by two, and 1/2 by two square tubularsteel with typically 0.063 to 0.125 inch wallthickness. The mold panel size betweenframing members is generally no larger thanfour inch by six inch to six inch by eight inch.The frame is tacked together and thenremoved from the mold for final welding. In aproperly constructed frame, all the steelelements are carefully fitted and welded onall sides. End caps are placed over all openends.

The completed frame is fitted onto the mold,filling the gap between the frame and themold with a bedding mixture of resin andeither glass or ceramic microspheres.Before doing this, the mold is covered withrelease film. This allows the bedding mixtureto bond to the steel frame but not to themold laminate. The steel frame should bethoroughly cleaned on the contact surfaces,and a brush coat of resin should be appliedbefore installation. This will help the steelbond to the bedding mixture. After cure, theassembly of frame and bedding mixture isremoved. Grinding on the edges of thebedding mixture provides a neater, cleanerappearance. Finally, silicone sealant isapplied to the bedding material contactsurface, and the frame assembly is installedpermanently on the mold.

3) Tooling, Upper Mold Type—The upper moldcan take many forms, depending on theparticular process. Most closed mold setsuse a silicone rubber seal for processreasons related to mold filling, and forhousekeeping purposes. Resin leaks, drips,and puddles during the mold fill processshould be avoided through mold designfeatures. This is important because once theresin has cured, a chisel and hammer isoften used to clean off the resin debris.There is no greater threat to a mold’s longand productive life than a hammer and

chisel. Any place that is likely to collect resinshould be coated with a layer of silicone,about 1/4 inch thick. This will allow themolder to pry out the cured resin rather thanusing a grinder or chisel.

Many upper molds have two seals, innerand outer. In some cases, this is a primaryand a backup seal. With some separationbetween the seals, a vacuum chamber canbe made around the part perimeter. Thischamber can have two functions: providingthe mold clamping force in VacuumClamping processes; and porting vacuum tothe part perimeter in Pressure to Vacuum orVacuum to Vacuum processes. Thesevacuum ports can be point vents, made byplacing a vacuum venting material throughthe inner seal. Or, the entire perimeter canbe vented by careful design andconstruction of the pinch-off area.

4) Creating the Mold Cavity—The Upper Moldis usually constructed using the Lower Moldas a platform. There are various cavities thatwill exist between the upper and lowermolds. To produce these cavities, two majormethods can be used.

For the upper mold Rigidized Laminate,considerable cost is incurred duringconstruction of the upper mold. The otherreusable upper mold types are either lessexpensive to remake (Shell Laminate) orsomewhat forgiving (Elastomeric Multi-Use)with respect to cavity variations. However,for the upper mold Rigidized Laminate, it isvery important to know what partthicknesses and glass loadings are required.Once the upper mold is made, these cannotbe changed without going to considerableexpense. Simply adding glass will changethe flow characteristics, making the mold-filling process difficult or impossible. It ispreferable to demonstrate a sound part

Tooling/Creating the Mold Cavity continued:

design before building the upper mold.

Using the lower mold, a complete part



Page 8 of 21


should be carefully hand-laminated.Thorough attention to glass loading andglass/resin ratio should be exercised. Coresor inserts, if present in the design, should beinstalled during the lamination process. Thepart should be tested sufficiently to proveout the design before proceeding withdesigning and building the upper moldpattern.

5) Dimensional Waxing—Dimensional waxingis probably the most economical andaccurate means for producing the partcavities. Starting with the lower mold, thedimensional wax is applied to mimic the partthickness. Wax stock is currently available ina wide range of thicknesses and severaltemperature ranges. It is important to usethe high temperature variety due to theexotherm heat generated during mold cure.The adhesive backing helps keep the wax inposition. Dimensional waxing is very muchan art requiring skill and finesse for accuratethickness control.

Dimensional waxing is most successfullyaccomplished in a temperature-controlledenvironment. Sometimes, dimensional waxis applied in two layers. The first layer isthinner and placed as tiles with channelsbetween pieces. These channels form avacuum manifold. This vacuum manifoldserves to hold the second, thicker layer inplace. This configuration can reduce thelikelihood of prerelease during the gel andlamination stages of mold building. Ingeneral, it contributes to higher accuracy inthe mold cavity dimension. Clay can be usedto produce fillets in tight radii and to fill theseams between adjacent courses of wax.The preferred clays are very stiff at roomtemperature. A hard clay produces a bettergel coat surface on the cured mold. A heatlamp or other kind of hot box is usuallyrequired to condition the clay so it can beeasily molded. Once it cools, the claybecomes very stiff and provides a goodmolding surface. Some clays can inhibit thegel coat cure during mold fabrication, so the

clay should be checked to ensure this doesnot occur.

The surface quality of the uppermold half depends critically on thequality of the dimensional wax andclay installation. Careful attention to detailwill result in the least re-work to the uppermold.

Prior to constructing the upper mold half,paste wax is applied over the clay anddimensional wax. Then PVA is sprayed overthe paste wax to serve as a parting filmbetween the pattern and the mold. When theupper mold is Elastomeric Multi-Use, a soapsolution is instead sprayed on the pattern tofacilitate release of the silicone bag material.It is important to test new combinations ofmaterials on a small scale before expectingthem to work on a large scale.

6) Master Part—The mold cavity can also bepatterned by building a master part. Ingeneral, cavity thicknesses have greatervariation when using the master part versusthe dimensional waxing method. In the lowermold, a complete part should be carefullyhand laminated. Very careful attention toglass loading and glass to resin ratio shouldbe exercised. Any cores or inserts should beinstalled during the lamination process. Theentire top surface is then sanded smooth.Body putty is used to fill major imperfections.The top surface is covered with a highquality surfacing primer followed by toolinggel coat which is sanded and buffed to ahigh gloss. This preparation adds to thecavity size, so careful planning andexecution is necessary to end up with theproper cavity. Also, keep in mind that femaleedges and corners have greater thicknessvariations; this results in resin rich areas onthe production part. See the section onPolyester Tooling for more information onbuilding patterns and plugs.

7) The Pinch-Off—The pinch-off is a moldfeature that can serve several functions. Thepinch-off is that certain part of the mold



Page 9 of 21


Tooling continued:

cavity at the edge of the part where the twomold halves come together. The moldmating flange is just outside the pinch-off.There is still a gap between mold halves inthe pinch-off. Generally, the same or smallergap is carried onto the mating flanges. In thepinch-off, the separation distance is muchless than in the cavity area. In general,0.015 inch of pinch-off space is allowed forevery 1.5 osf of CFM. In comparison, 0.045inch of cavity space filled with one 1.5 osf ofCFM provides a laminate with 30 weightpercent glass (zero filler load)). The pinch-off compresses the CFM to roughly one-thirdits original height. This makes the glasspack less permeable and the liquid resincannot easily penetrate this area. Thisprevents the resin from wetting out thelaminate in or past the pinch-off area.

Immediately after molding, while the part isstill not fully cured, the flashing can be tornoff the part by hand or cut off with a hookknife. The flashing and the part separate atthe pinch-off area. This type of part edge isadequate for some applications. For manyapplications, the part edge will need to be ahigh-quality cut edge.

The pinch-off also provides a vent path forthe fiber pack. Air will vent through thepinch-off while the glass is still dry. Avacuum plenum must be provided outsidethe pinch-off area, in either the lower orupper molds. Once the resin arrives andwets the glass, air will no longer ventthrough the pinch-off. At the vent locations,the pinch-off is interrupted by making achannel from the part to the vent. Thisimproves the effectiveness of the vent.

8) The Rigidized Laminate Upper Mold—TheRigidized Laminate upper mold is usedwhenever there are substantial resinpressures and/or large mold closing forces.This mold type is typically used in RTM.

In general, this mold is a glass laminatefitted to a heavy steel frame. See the Lower

Mold Robust section for a typical molddescription. Generally, the mold flange hastwo rubber perimeter seals. In the Pressureto Vacuum process, the space between theseals serves as a perimeter vacuummanifold.

The upper mold ,Rigidized Laminate, moldset is the heaviest of all. For example, a partlarger than two square feet will have a moldtoo heavy to Hand Lift during demold. Thissystem has the potential for the fastestproduction rates in very sophisticatedprocesses. The upper mold RigidizedLaminate mold set is the most durable of thevarious molds and can be expected to havethe longest life.

Parts that require gel coat present a specialchallenge for the Rigidized Laminate moldprocess. The extra process time for sprayingand curing the gel coat extends cycle time.In addition, there are often cosmeticrequirements for gel-coated parts thatdemand excellent surface profile withoutdistortion or fiber print. Rapid cycle timesand quick demold events allow the part tocure without being in contact with the moldsurface; this compromises cosmetic quality.To address both of these issues, the lowermold can incorporate two features: a dishand a pan. The dish contains the actualmold surface but no support framewhatsoever. The pan is a lower supportmold that holds the dish. This lower supportmold is a glass laminate mold with a veryrobust steel frame. Vacuum between thepan and the dish ensures that they nestperfectly. As a result, the supporting panmold reacts the injection pressures duringthe mold fill process. Several of these dishescan be fabricated for each pan.

These dishes can be gel coated off line fromthe molding station. The gel-coated disheswould then be processed, in sequence,

Tooling/ The Rigidized Laminate UpperMold continued:

through the mold station. After the part is



Page 10 of 21


molded, it can remain in the dish for someperiod of time. This will improve surfacecosmetics in addition to throughput.

9) The Shell Laminate Upper Mold—The Shellupper mold will probably enjoy the mostwidespread use for small production runparts. This is largely because existing openmold assets can be readily converted toaccept this type of upper mold. In addition,this upper mold is both the least expensiveto fabricate and uses no new chemistry. Thisupper mold is a thin glass laminate with aspecial flange detail. The flange detailusually has two seals. A vacuum applied tothe cavity between the two seals usuallyprovides the clamping force (VacuumClamps). In addition, vacuum venting to thepart cavity can provide clamping forcesacross the entire part.

The Shell Laminate upper mold is similar tothe Rigidized Laminate upper mold in thatboth are made with glass laminate. But theShell Laminate is much thinner and has littleor no framing.

The Shell Laminate upper mold generally isone of two types based on the flange detail.Both provide for a clamping force but theydiffer in resin transfer functions. One appliesa vacuum to the part perimeter for adiverging flow fill from the part center to theedges. The other provides an Edge Manifoldthat serves as the resin pathway into thefiber pack for a converging flow fill to a ventat the part’s flow center. Schematicdiagrams for diverging and converging flowfields can be found in the section on GeneralConsiderations to Controlling Flow.

A typical flange detail is presented in Figure5/IV.6. There are two popular ways todevelop the flange detail. The preferredmethod is to pattern the flange detail aroundthe perimeter of the mold using dimensionalwaxing and other conventional patternbuilding techniques. In this method, theflange is laminated when the upper mold islaminated, except the flange is usually

thicker. The other method is to miter andbutt prefabricated stock lengths of a flangedetail around the part perimeter. When theupper mold is laminated, narrow strips ofwet glass are placed across the flange buttjoints, and the laminate in the part cavity islapped over the flange pieces, thus forminga one piece upper mold and flange.

The Shell Laminate upper mold can be builtby spraying clear gel coat over the preparedand properly released pattern, followed bylaminating the mold. Clear gel coat provides

Figure 5/IV.6 - A flange detail for the upper mold shell

laminate type incorporates two seals and a vacuum

clamp chamber to hold the upper mold to the lower

mold.

an upper mold that is translucent so that onecan watch the fill process when the uppermold is used. The laminate thickness isgenerally four to 12 osf CSM over the partcavity and four to 18 osf CSM over theflange. The thickness is strongly dependentupon the part geometry. Lamination stagesare limited to 1.5 osf for skin coat, and threeosf per lamination operation to avoid excessheat generation.

The flange detail commonly has someprovision for alignment. Sometimes thelower mold will have an upturn flange at itsoutermost perimeter that is matchedcorrespondingly by the upper mold flange.Sometimes, it is a downturn flange. Thedimensions needed for successful locating



Page 11 of 21


will depend on the overall part area anddepth. If no provision is made for locating,then the overall part shape will try to locatethe two mold halves. However, slightmisalignments will cause fractures in edgeand corner locations of the upper mold thatresult in reduced mold life.

The Shell Laminate upper mold is a durablemold that will endure many molding cycleswhen properly built and properly cared for.Mold failure is generally characterized byfracture of the laminate in edges andcorners. This is aggravated by a poor fit inthe corner and/or inadequate alignmentfeatures in the molds.

Tooling continued:

10) The Elastomer Multi-Use Upper Mold—TheElastomer Multi-Use systems generally usesilicone vacuum bags. Be advised thatsilicone is a chemical class just likepolyester, and there are many differentformulations from single component to twocomponent, and either addition cure orcondensation cure varieties. It is importantto demonstrate compatibility between thesilicone and the molding resin. The cure ofpolyester resin can be inhibited when incontact with certain materials.

There are two types of multi-use bags,typically designated as conformal or non-conformal. Non-conformal bags arefabricated from flat sheets of calenderedsilicone. These are limited to parts with a flatprofile and mild curvature. The typicaltechnique for joining adjacent pieces usuallyinvolves butt splices of calendered materialcovered with a lap of uncured rubber. Heatcuring is accomplished under a Single-Usevacuum bag.

Conformal bags are molded to the part’supper mold line. They can be molded fromcalendered sheet stock that is partially curedor from bulk silicone material. For thecalendered stock, pieces are applied tocover the pattern, a Bag Film Single-Usevacuum bag is applied, and it is cured in an

oven. For the bulk silicone, it is applied tothe pattern surface by brushing or othermeans. Often, a polypropylene mesh orsome other flexible reinforcement isembedded in the silicone to provide strengthand durability. Some varieties of silicone willcure at room temperature.

The flange detail can range from a tackyrubber seal tape to an aluminum orfiberglass flange detail with EPDM, silicone,or neoprene rubber seals. The flange detailmay provide a vacuum chamber around thepart perimeter. For small parts, this type ofbag is easily handled. For large parts,handling becomes difficult and it becomeseasy to tear or damage the bag. Improperstorage can result in damage and prematurebag failure.

A ‘V’ or ‘C’ groove in the lower mold flangecan also serve as a seal for the elastomermulti-use upper mold. When the upper moldis fabricated, this groove in the lower mold isfilled with elastomer. The elastomer extendsbeyond the groove as well. Simply placingthe upper mold in place around the lowermold flange provides the seal once vacuumis applied. In some cases, a vacuum plenum(groove) in the lower mold flange (which isnot replicated in the upper mold), locatedjust inboard of this seal groove must beused to ensure the upper mold seal integrity.

11) The Bag Film Single-Use Upper Mold—TheBag Film Single-Use systems use theclassic vacuum bag constructed from rollstock material. This method enjoyswidespread use both in the aerospaceindustry and with very large fiberglass parts.Each time the part is built, a new vacuumbag is constructed. This method is typicallyused for parts that have small productionruns and low production rates.

There are two fundamental approaches tovacuum bagging: surface bagging andenvelope bagging. In surface bagging, thevacuum bag is sealed to the tool face. Thetool should not contain any penetrations that



Page 12 of 21


would cause leaks. The tool laminate canalso leak vacuum if it has porosity. Thisporosity can be repaired by using a vacuumbag to draw a vacuum on one side of themold face while painting an elastomeric sealmaterial on the back side. Vacuum forceswill draw the seal material into the porosityand seal the mold face. Several applicationsmay be necessary. In envelope bagging, thevacuum bag completely encapsulates thetool. This is only practical on smaller,somewhat flat parts.

There are a few items which are commonlyused to construct vacuum bags, althoughnot all of them are always used. These itemsare: Peel Ply; Release Film; BreatherMaterial; Bleeder Material; and BaggingFilm. All of these items are consideredexpendable goods. In other words, one buysthem for each part and throws them awayonce the part is cured. This is practical forlow production run products, but is tooexpensive for higher volume applications.

Peel ply is a nylon, polyester or fiberglassfabric that is laminated into the part surface.The fibers in the peel ply are treated (or leftuntreated) so that no bond occurs with thelaminating resin. Some time after the part islaminated, the peel ply is removed bypeeling it off, hence the name. This leaves aclean, slightly textured surface that can bebonded to or painted on without furthersurface preparation, provided it is not leftopen to the air for an extended time.

Release film is a film that doesn’t bond toresin. It is used to ensure a part does notbond to another item, such as vacuumbreather or vacuum bag. It can beperforated to allow resin or vacuum to passthrough, or nonperforated which preventsresin or gasses from passing through.Release film is always in contact with thelaminate. It forms the border between thepart and the vacuum bag system.

Breather is a key element of the vacuumbag system. Without breather, the forces on

the vacuum bag are not consistent from onespot to another. In fact, some areas of thevacuum bag may have no force whatsoever.

Figure 5/IV.7 - A vacuum bag system may incorporate

the vacuum bag, vacuum breather, and a release film.

No resin transfer plumbing is shown in this view.

This is because the vacuum bag, in contactwith either a mold surface or a wet laminate,will tend to seal off and not pass thevacuum. A breather works to vent vacuumunder the bag everywhere the breathermaterial is. Breather is usually a spun matmade from a polymer fiber. A non-wovenpaper product such as handy wipes is anexample of a low cost breather.

Bleeder is used to extract (soak up) excessresin that exits a part. It generally is used inconjunction with perforated release film. Therelease film prevents the bleeder stock frombecoming part of the laminate. The bleedercan be any type of fibrous material. Polymerfiber such as spun polyester fiber iscommon. Glass stock can also be used at agreater expense.

Bagging film is the last layer. It is the layerthat the atmospheric pressure acts upon.

In general, this is a nylon film that iscarefully selected for its good elongationproperties. It forms the boundary betweenthe vacuum and the atmosphere. Thispressure difference results in a compactionforce. Many types of nylon film areplasticized by moisture. The ambienthumidity has a strong effect on the bagmaterial’s softness and elongation. If a roll ofbag film dries out, it becomes very crinkly



Page 13 of 21


and hard to work. The bag stock can berestored to usable form by putting it in a tentwith an ordinary vaporizer. Once the filmabsorbs some moisture, its desiredproperties will return.

The bag is sealed to the flange using asealing tape that is a rubber based materialwith high tack. A common size is 1/8 inch x1/2 inch in 25 foot rolls. Since the bag ismade from flat roll stock, numerous pleatsare used to fit the bag into and onto edgesand corners.

All the items mentioned above areconsidered disposable items and areconsumed during each molding cycle.

12) Mold Seals—Most molds for Resin TransferMolding have rubber extrusions for seals.Many times, a double seal arrangement isused. Various synthetic elastomers areused, such as polysiloxane (silicone),polychloroprene (neoprene), and ethylene-propylene-diene monomer (EPDM) rubber.Numerous cross-sections are available. Theseal and its geometry has a strong effect onthe design of all upper mold flanges that are

Tooling/ Mold Seals continued:

re-usable. Silicone seals are almost alwaysused at the part boundary. Resin doesn’tstick to the silicone, making moldmaintenance easier. The backup seal isgenerally EPDM rubber, which is much lessexpensive than silicone. Some processesuse neoprene rubber seals.

D. Clamping Method—The Clamping Method hasa cost in terms of capital requirements with acorresponding benefit in cycle time. Part sizestrongly influences the choices of clamping method,but the biggest driver is the way the resin pressurehead is developed. The general clamping types areVacuum Clamps, Mechanical Clamps, PneumaticClamps and Hydraulic Clamps.

1) Vacuum Clamps—Vacuum Clamps are avery useful and practical way to clampmolds together. In general, vacuum clampsconsist of two rigid shells that come into

contact with a rubber seal between them.These shells form the boundary of a cavity.When vacuum is applied to the cavity,atmospheric pressure forces the shellstogether. The size of the cavity and the levelof vacuum will determine the magnitude ofthe clamping force.

A schematic for a perimeter vacuum clampcan be found in Figure 5/IV.6. See theexample of a typical flange detail for ShellLaminate upper molds.

Sometimes, a vacuum clamp arrangementconsists of a single seal that surrounds thepart cavity. Vacuum is applied in awholesale fashion to the part cavity toprovide the clamping function as shown inFigure 5/IV.8.

2) Mechanical Clamps—Mechanical clampsare generally very robust and located atapproximately 18 inch intervals around theperimeter. Clamp locations are generallyreinforced with 3/8 inch or 1/2 inch thicksteel plate. Generally, the clamps provide forthe alignment of the upper and lower molds.Screw clamps are typically two machinedpieces that provide alignment. Generally, a 1inch diameter bolt through the top piece anda replaceable nut in the bottom pieceprovide the clamping force. Toggle Clampsinclude a pair of hooks with a leverarrangement like a break-over clamp toprovide the clamping force. One of the hookelements has a provision for lengthadjustment. Welding of the final clampelements usually doesn’t occur until theupper mold frame is constructed. At thattime, the clamp/alignment elements are heldin the tightly closed position while they arewelded in place to ensure their alignment.

3) Pneumatic Clamps—Pneumatic Clampsgenerally consist of two horizontal andessentially parallel platens and an air bag. Ina pneumatic press, the platens don’t need tobe perfectly parallel, but they do need to bevery flat. The platens are held a fixeddistance apart by a number of large



Page 14 of 21


threaded rods with heavy duty nutspositioned above the upper platen and someholding nuts below the upper platen. Thisallows for some variation in the height of theclosed mold set. It is not a trivial matter toadjust this height, so limited production runsshould be made with molds that are nearlythe same height. The closed mold set isshuttled into position between the platens.There is only a small empty space betweenthe mold set and the top platen. An air bagbuilt into the lower platen inflates and liftsthe mold set upward against the upperplaten. Since the air bag inflates quite a bit,and since it inflates until it closes the gap, itcompensates for the fact that the platensmay not be exactly parallel, as long as theyare truly flat. This is not the case for ahydraulic press; the quality of a hydraulicplaten press is directly determined by howparallel, in addition to how flat, its platensare.

Figure 5/IV.8 -In the RTM configuration, vacuum applied to the

mold cavity results in a clamping force across the entire part.

Here the resin is applied before the upper mold is installed.

Figure 5/IV.9 -The pneumatic press uses compressed air to

inflate an airbag. This forces the assembled mold set upward

against the upper platen, clamping the upper and lower molds

together.

4) There are two types of hydraulic clampingsystems. The first is a platen press. Thesecond type uses a number of hydrauliccylinders placed around the mold perimeter.

One design uses offset geometry to movethe clamp’s claw out of the way during theopening motion. The closing motion movesthe clamp into position for applying theclamping force. In this way, the upper moldcan be lifted clear of the lower mold. Asecond design uses pneumatic cylinders toswing the hydraulic clamp elements out ofthe way so the mold can be opened, andback in place so the clamping force can beapplied. Unless a mold set is run non stop,the cost of hydraulic systems limits theflexibility of this system. This can beaddressed by the use of a clamping framedevice. This clamping frame can be usedwith similarly sized closed molds. Aparticular closed mold set is installed in theclamping frame and a brief production run isthen executed.



Page 15 of 21


E. Mold Set Open-Close Method—The Open-Close Method has a cost in terms of capitalrequirements with a corresponding benefit in cycletime. The size and weight of the mold is the biggestdriver for selecting the Open-Close method. Thecycle time is the next biggest driver.

For small molds and moderate production rates, theHand Lift method is frequently used. In general, if ittakes more than two people to lift and handle amold, another method becomes preferred.

There are several variations of Mechanical Hoist. Awinch is the least expensive and most cumbersometo use. A manual chain hoist is generally used onlyfor limited production rate, mold building, or researchand development processes. Most often, the electricchain hoist is used. Often, two or three hoists areused simultaneously on one mold. This method hasthe greatest flexibility at the lowest cost, but onlyprovides moderate production rates.

When the desired production rate is faster and whenthe mold is large and heavy, a custom manipulator isused to open and close the mold. The controls for amanipulator can vary in sophistication. For a simplecontrol system, there is a greater likelihood foroperator error. A very complex control system canuse a Programmable Logic Controller (PLC) to applylogic in process operation. In general, a manipulatoris a large steel structure with actuators to move themold halves. Some actuators may separate the moldhalves while others may shuttle a mold half to theloading or gel coating station. The cylinders can bePneumatic Actuators or Hydraulic Actuators. Ingeneral, pneumatic actuators cost less and hydraulicactuators can apply greater forces.

F. Equipment—The equipment for Resin TransferMolding can range from a few C-clamps, paper tubs,wooden stir sticks, and a catalyst bottle to upwardsof hundreds of thousands of dollars in facilities andequipment. We will discuss some of the generalitems below.

1) Pressure Systems—There are two methodsof providing resin under pressure. Apressure pot is the least capital intensivemethod. A standard injection machine is themore capital intensive. For the pressure pot,the pickup tube is one end of the

polyethylene tubing that directs the resin tothe mold. Catalyzed resin is placed in adisposable tub inside the pressure pot sothat valuable solvent is not expended oncleaning functions. Compressed air providesthe pressure head that forces the resinthrough the system.

The injection machine is generally a dualpositive displacement pump arrangementdriven by an air motor. Different pumpconfigurations and lever arrangementsprovide settings for varying catalyst ratio.Conceptually, it is the same system that isused for modern choppers and gel coat unitsalthough variations in pumps and provisionsfor ratios may vary.

2) Vacuum Systems—There are two basicmeans of providing a vacuum source: aventuri or a mechanical vacuum pump. Aventuri uses compressed air to produce avacuum. This is the lowest capitalinvestment option, but the vacuum flow rates

Figure 5/IV.10 -A standard pressure pot can be modified to

deliver resin under pressure or vacuum.



Page 16 of 21


Equipment continued:

are small and the compressed airrequirements are large. It is not the mosteconomical source of vacuum for largedemands, but it is an excellent source of

vacuum for R&D functions, for mold making,and for limited production. A venturi vacuumsystem can be pieced together for less than$50 in parts costs. An assembled systemwill cost from $300 to $500.

A moderate-size, industrial-style vacuumpump system can be purchased for lessthan $5,000. Such a system has a vacuumcutoff switch to provide a preset range ofvacuum and a tank similar to an aircompressor system. The compressor andtank size should be chosen based oncurrent and near-term projected vacuumneeds. The plumbing throughout a plantdoes contribute to the tank size. Ordinary 4inch diameter, Schedule 40 PVC pipe iscommonly used to plumb vacuumthroughout a facility. This can addconsiderably to the volume of the vacuumstorage tank and improves drawdowncapacity.

Vacuum regulators are approximately 10times the cost of conventional compressedair regulators. In some instances, separatelow and high vacuum systems areeconomical. The very low vacuum systemcan use a shop vac. This is useful forevacuating large amounts of air to a slightvacuum. This is especially valuable in theBag Film Single-Use processes. Once thelow vacuum evacuation is complete, onecan switch to the higher vacuum system forthe resin injection process.

3) Resin & Vacuum Plumbing—Once theresin is catalyzed, it is plumbed to the mold.The resin enters the mold through aninjection port, the mold fills, and the resinmay exit the mold through a vent port. If theresin is allowed to cure in the plumbing,some provision for removing it will beneeded. In simple systems, the injection

Figure 5/IV.11 -Resin trap separates the vacuum system from the

part cavity in Pressure to Vacuum and Atmosphere to Vacuum

resin transfer schemes.

and vent ports can be drilled out betweenparts. Another method uses disposablepolyethylene tubing that lines the metalinjection or vent port. It is discarded betweenparts. A third method uses a valve body thatdirects catalyzed resin into the mold. Whenflow is complete, the valve body seals themold. Solvent is used to flush the lines andvalve body. The solvent and resin waste isthen plumbed into a covered wastecontainer. Such a valve body can also befitted to the vent ports.

When vacuum is applied to the vent port, aresin trap is placed in the plumbing betweenthe mold and the vacuum system. This trapis a reservoir that catches resin andprevents it from entering the vacuumsystem. A resin trap is shown schematicallyin Figure 5/IV.11.



Page 17 of 21


An air ejector is a device that is molded intothe closed mold. It is used to blow (not push)the part out of the mold. It consists of acylindrical housing with a cylindrical pistondevice at its center. It works by using twocompressed air lines. While the part is beingmolded, one of the compressed air linesapplies air pressure to hold the piston tokeep the ejector port closed. To demold, theother compressed air line is used to movethe piston away from the part surface. Thiscauses a gap between the piston and thepart surface. Compressed air flows into thisgap and releases the part. A schematic isshown in Figure 5/IV.12.

4) Hydraulic Pressure Systems—Hydraulicsystems can be used to clamp molds in highrate production processes. A small system,with a pump, cooler, accumulator, valves,hoses, and 8 hydraulic cylinders would costabout $10,000. They tend to be durablesystems. Pumps can be rebuilt, as can mostcylinders. This type of equipment can beused on a clamping frame that willaccommodate a variety of similarly sizedmolds. Such a configuration is like a minihydraulic platen press. Hydraulic platenpresses are very expensive and quickly run

into the hundreds of thousands of dollars.Hydraulic clamping systems are only usedon the highest production rate processes.

Figure 5/IV.12 -When compressed air is applied to Line 1, the

ejector piston is held in contact with the part surface. When

compressed air is applied to Line 2, the ejector piston moves

away from the part surface, allowing compressed air to release

the part from the mold.



Page 18 of 21


G. Troubleshooting

PROBLEM POTENTIAL CAUSES POTENTIAL SOLUTION

Laminate shell mold

cracks in edges and

corners .................... Mold too thick ..................................................

Mold not aligning well during closing.........

Mold cavity too thick in edges and corners

...................................................................

Reduce thickness and use aligned fiber

reinforcement.

Alignment devices must engage before part features

force alignment.

During patterning, dimensional wax should not

bridge corners and/or the master part must not be

too thick.

Mold does not fill ..... Injection location(s) not in best spot ..........

Vent location(s) not in best spot ................

Part cavity too thin for the glass loading ...

Try new locations.

Try new locations.

Redesign part cavity and/or glass loading.

Dry spots in part ...... Resin flow front splits in two at start of dry

spot and rejoins at end of dry spot ............ Put vent at dry spot to allow air to escape.

Modify injection location.

Mold leaks resin ...... Mold seal not compressed ........................

Mold pieces don’t fit well ...........................

Add spacer to mold seal groove under mold seal

rubber to shim it outward.

Redesign geometries.

Warpage or

distortion of molded

part .......................... Cure and shrinkage after demolding ........

Incomplete cure ........................................

Unsymmetric laminate...............................

Cool parts in jigs to maintain shape.

Delay demold point to allow more cure.

Increase molding temperature.

Increase catalyst level.

Switch to hotter catalyst.

Change resin promoter package.

Correct unsymmetry.



Page 19 of 21



Page 20 of 21







Page 21 of 21

LOW VOLUME CLOSED MOLDING: Converting from Open Molding


Part Five, Chapter VCopyright 2008


2. Design and Prototyping

3. Designing the Reinforcement Package

4. Closed Mold Design Details

5. Patterning the Upper Mold

6. Closed Mold Fabrication

7. Upstream Processes

8. Executing the Closed Mold Process

9. Discussion of Vacuum

1. INTRODUCTION—The term ‘Best Practices’describes the actions and considerations that produce asort of optimum set of results. Many times, these actionsare arguable, depending upon which ‘optimum’ isdesired. Some things depend upon the specific partdesign and production plan. For the purposes of thissection of the manual, the ‘Best Practices’ are thoseactions and considerations that contribute to successfulproduction of gel-coated cosmetic parts with high as-molded quality for production runs of hundreds tothousands of parts.

Closed molding presents some unique challenges to theestablished open molder. It is most important to focus onthe product development process from part designthrough production scale-up. Figure 5/V.1 presents thisprocess in the context of ‘Best Practices’ for minimumcost.

Large quantities of small, non-gel coated parts are bestproduced using conventional, High-Pressure RTM.Rapid cycle times are necessary to offset the hightooling costs. Rapid cycles are achieved with acombination of High-Pressure injection, heated molds todrive the cure, and hydraulic actuation to rapidly openand close the mold set. The upstream process of gelcoat application/cure can easily double the cycle time,challenging the economics and applicability of high-

pressure RTM. It is the most expensive process for largeparts.

Shell Laminate (Light RTM) is the process of choice formost parts without any negative draft. The process useslow-pressure injection to vacuum venting with vacuumclamping. The upper molds should be consideredsemidisposable for optimum economics. There is verylittle benefit from flow media because the upper mold isrigid enough to prevent the glass pack from becomingcompletely compressed, and a positive displacementresin pump provides a suitable pressure drop.

Silicone Bag RTM, with low-pressure injection to vacuumventing, is the process of choice for die-lockedgeometries or parts with exceptionally deep draws.Some shops appreciate the ability to fold the uppermolds and store them in a pigeon-hole shelf unit. Flowmedia provide little benefit because the resin transferoperation inflates the cavity, and resin flows quicklyacross the glass pack top surface in the manner of atemporary face manifold. The high cost of siliconerelative to fiberglass will always make this processslightly more costly than Shell Laminate RTM.

Vacuum Infusion is the process of choice for limitedproduction runs or for parts that require high glasscontents. Some means of bulking the laminate isnecessary to achieve thicknesses common to open molddesigns. Extremely large parts are also good candidatesfor vacuum infusion, although these are usually limited-number production parts anyway. Flow media arerequired in vacuum infusion. Under vacuum and withouta resin pump, the flexible bagging film compresses theglass pack considerably, reducing permeability and flowvelocity below practical limits. Surface flow media areoften removed and discarded after molding. Interlaminarflow media are becoming more popular, although theydo provide lower interlaminar shear strength than aglass-reinforced ply. Since the bagging film is notreusable the cost recurs with each part manufactured.

2. DESIGN AND PROTOTYPING—A prototype is anecessary step in a product’s development. Theprototype serves to validate the design’s fit, form, and



Page 1 of 16

LOW VOLUME CLOSED MOLDING: Converting from Open MoldingCopyright 2008

DESIGN AND PROTOTYPING continued:function. Many times, the process is abbreviated by notaddressing function. Fit and form are evaluated for theprototype, but function is not evaluated until further downthe product development cycle when it is sometimesdiscovered via a product failure. In open molding, thesolution manifests itself in changes to the laminateschedule. A part is designed, a pattern is prepared, amold is constructed, and a part is produced. The part is

evaluated for fit and form, and the design is certified asacceptable. If function is later found to be lacking,additional reinforcement materials can be added to anopen-molded part without much concern for the molddesign.

When the upper mold comprises vacuum bag film orsilicone rubber, adding additional plies of material toincrease part strength and stiffness is equallynonconsequential. But when the upper mold is rigid,adding additional plies of material becomes problematic.The part cavity remains the same. Thus, the plies mustbe compressed to a greater extent, with a corresponding

decrease in their permeability. At some point, the pliesbecome so compressed that they don’t wet out properlyand don’t exhibit their normal strength. White fiberbundles visible at the part surface are evidence ofinadequate wet out. Further ply compression can evenprevent resin from flowing through the region, resultingin dry spots.

Many variables work toward or against proper andconsistent mold filling. The biggest factor is theconsistency of the glass fiber pack. Best results areachieved by controlling the type and amount ofreinforcement, as well as the location and extent of plyoverlaps. This is achieved by designing the ply kit beforethe mold cavity is designed. This requires materialselection prior to ply kit design, and includes not only thetype of glass reinforcement, but the specific form(usually width) for that glass type. The benefits of thisapproach are two-fold: Minimizing material waste; and,ensuring consistent mold-fill performance.

3. DESIGNING THE REINFORCEMENT PACKAGE—There are various methods of preparing the reinforcingpack, including:

A. Preforming—This method produces thereinforcing pack in a upstream operation known aspreforming. The preform is placed dry in the emptymold, the mold set closed, and the resin injected.The most rapid cycle times are achieved using thepreform approach. The reinforcement pack can alsobe assembled in the empty RTM mold. The lowermold is engaged during this process, which addsdirectly to cycle time.

B. Continuous Filament Mat (CFM)—The mostcommon reinforcement, Continuous Filament Mat(CFM), is also the least expensive. Its architectureresults in resin-rich and fiber-rich areas that result inmore fiber print than other materials. It is not veryconformable and requires cutting and darting forcomplex geometries. CFM is the most commonlyused reinforcement for conventional RTMprocesses.

C. Stitched Chopped Strand Mat (StitchedCSM)—Offers much greater conformability thatCFM, the polymer fiber cross-stitches in StitchedCSM prevent the fiber wash that would be seenduring the fill process with ordinary Chopped StrandMat.



Page 2 of 16


D. Other Options—Other stitched materials areused as structural materials. These are available ina wide variety of configurations, often with three ormore distinct layers. A common example is 1808material. This is a three-layer material. The first layeris aligned glass fiber in the warp direction, while thesecond layer is aligned glass fiber in the weftdirection, and the third layer is chopped mat.

E. Special Constructions—One interestingproduct comprises two layers of glass reinforcementseparated by a layer of polymer fiber core. Thepolymer fiber core adds thickness, and thus bendingstiffness, without the full weight of a glass ply.Available from several sources, these materials tendto be very conformable and provide good cosmetics.They do suffer from reduced inter-laminar shearstrength due to the low strength of a polyethylene orpolypropylene fiber ply.

A spun-bound polymer fiber ply works effectively asa print blocker when placed against the gel coatlayer. With this approach, there is a trade-offbetween the cosmetic quality and the tendency ofthe gel coat layer to crack.

In vacuum infusion, the flexible bag film upper moldtends to compress the glass reinforcement so muchthat the permeability becomes very low, andtherefore, the resin flows very slowly. Certainmaterials have been designed that resistcompression and provide a ready flow path for theresin. These can be placed within the laminatethickness, or above the laminate for subsequentremoval.

The ply kit must be designed and proven beforedesigning the mold cavity. Material types and formsare selected by fiber architecture, areal weight andwidth, respectively. The ply kit is designed bydetermining the minimum number of lineal feetrequired of that width material to build the partthickness. This usually requires ply splices to belocated somewhere on the part. Figure 5/V.2illustrates how intentional ply splices can be used tominimize roll goods usage. Any overlap areas aredesigned in the part cavity in the form of additionalthickness. This approach ensures consistent fillingduring the resin transfer operation by eliminatinghighly compressed areas in the reinforcement pack

that serve as flow restrictions.

Nesting plies in a ply kit is another method ofminimizing material usage. Nesting refers to theoperation of orienting different ply details so that thegreatest fraction of material is utilized. Plies fromdifferent parts should never be comingled in a singlenest for the same reason that different parts shouldnot be ganged together in a single mold; it leads tohigher material usage.

Figure 5/V.2



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Special Construction (cont'd)

Replacing any one scrap part requires production ofall the parts nested or ganged together. Nesting iscommon for aerospace designs in which individualply details are precisely designed. Nesting is not thelow cost approach to minimizing material usageunless the design is a minimum weight design. For aminimum weight design, ply splices must beprecisely controlled in order to ensure designintegrity. Ply splices are weak spots that must beaccounted for in strength analysis. Seldom are glassfiber polyester resin composites designed tominimum weight. More likely, they are designed tominimum cost. Usually, ply splices can be locatedwith concern for assembly fit tolerance and withoutregard for part strength provided that basic splicerules are followed. Above all, splices should neverbe superimposed through the thickness.

There are two types of splices: butt splices andoverlap splices. These are described as:

1) The butt splice comprises two ply detailsoriented so that the edge of one ply is adjacentto the other. A butt splice should be avoidedwhen the ply constitutes a significant fraction ofthe part thickness. Since the reinforcement isdiscontinuous across the splice, the joint issignificantly weaker than the area away from thesplice.

2) The overlap splice comprises two ply detailsoriented so that some portion of the end of oneply lies on top of the other. Overlap splicesprovide greater strength than butt splices.Overlap splices almost always require additionalpart thickness to accommodate the extrareinforcement material. Overlaps should neverbe less than 10 times the ply thickness. Forgood load transfer, the overlap ratio should be20 times the ply thickness or better.

Butt splices are preferred when assembly fittolerance requirements preclude additional partthickness.

Once the ply kit is designed, the materials should beused to hand laminate or vacuum infuse a part forprototype testing. This testing should evaluate partfunctionality and verify that the part thicknesses andreinforcements are adequate for the design. Careful

attention to glass content and part thickness isimperative to a successful structural evaluation.Once the laminate schedule is proven, the prototypepart should be cut into pieces to verify designthicknesses. Then, and only then, should the partcavity be designed and patterned.

4. CLOSED MOLD DESIGN DETAILS—Certaindesign details can greatly impact the performance of amold set on the factory floor. While they are not criticalfor success, they can contribute to the robustness of theprocess.

A. Closed Mold Features that AddRobustness—The mold set should be designed sothat the upper mold cannot be accidentally installedat the wrong clocking relative to the lower mold. Ifthe lower mold is oriented at 12 o’clock, it should notbe possible to close the mold at any orientationother than 12 o’clock.

Closed Mold Features that Add Robustnesscontinued:The mold halves should separate with a true verticalmotion. Many times, open mold parts are designedwith some negative draft that requires the part to bepulled somewhat horizontally prior to being movedvertically out of the mold. This should be avoided inclosed molding unless a device is fashioned to alignand move the mold pieces into the matedconfiguration. This will also require special sealextrusions for proper functioning.

For both the Shell Laminate and Silicone Bag RTMprocesses, the mold assembly procedure shouldrequire only moderate hand pressure and thevacuum clamps, without resorting to mechanicalclamps.

B. Closed Mold Framing and Thickness—For thethree process variations, laminate thickness,structural reinforcement, and construction materialsvary considerably. A conventional RTM processminimizes fill times with high injection pressures. Itsmold frame must not only support the weight of themold laminate, but also the injection pressures. Theframe itself must be structurally tied to the moldlaminate. Both the lower and upper mold must beheld to shape and clamped together. The highestpressures are at the injection point, which is usuallyat the part center. This area needs to be adequately



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reinforced to prevent mold cavity deformation.

In contrast, an open mold frame only serves tosupport the weight of the mold laminate. The openmold frame acts as a cradle to support the moldlaminate, with flexible glass laminate ties that don’tcouple the mold and frame structurally. This cradledesign is much more tolerant of thermal shock thanis a structural RTM framing system because thermalexpansion differences between the steelreinforcement and glass laminate are absorbed bydeflections of the light ties.

The shell laminate upper mold must be thin to resistcracking. This thinness allows the mold to bend andflex without generating a great deal of interlaminarshear stress. The laminate schedule should includeone 20 mil layer of tooling gel coat, a 10 milconformable glass veil directly against the gel coat,a chopped glass skin coat, and one layer of astructural material such as 1708 or 1808. These arenon-crimp fabrics with chopped mat stitched into athree-layer assembly. Additional thickness should beused over the vacuum clamps, edge manifold, andalignment devices. Vinyl ester should be theminimum grade resin material.

C. Closed Mold Alignment Devices—Problemswith aligning the mold halves can show up in variousways. The simplest feature is a thickness variation inthe part’s vertical walls. One side is thinner while theopposing side is correspondingly thicker. In othercases, certain geometric features work to align themolds after the outermost vacuum seal isestablished. When this happens, the mold is not freeto float into position. The interference that occurs atthese geometric features can cause stresses thatfracture a shell laminate upper mold. The resultingvacuum leaks will introduce air into the mold cavity,displacing resin and resulting in voids and/or dryspots in the part.

Extending the lower mold flange beyond the outerseal can provide a simple alignment feature. Anyalignment device must engage itself prior to thosefeatures on the part. Figure 5/V.3 shows analignment device that does not engage before partinterference occurs. A better design is shown inFigure 5/V.4. In this sketch, the height of thediagonal surface is slightly greater than the height of

the part features that otherwise would align themolds.

Three or four of these details are required to providemold alignment. These details also serve as wedgepoints when the upper mold needs additional forceto effect release, without causing damage to therubber seal extrusions.

D. Closed Mold Demold Devices—A commonproblem when converting from open mold laminationto closed molding occurs when a lower mold isdesigned according to the criteria ‘simply an openmold with a wide flange.’ For the open mold, the part

Figure 5/V.3 - In the upper and lower mold line sketchabove, the alignment device is ineffective. For clarity, notall mold features are depicted.

Figure 5/V.4 - In the upper and lower mold line sketchabove, the alignment device engages prior to flap sealcontact or part feature interference. For clarity, not allmold features are depicted.

edge is often located on a vertical but draftedsurface. The open-molded part is commonlylaminated with the glass reinforcement lapping overthe flange inside edge, extending sometimes beyondthe outside edge. This ‘flange laminate’ issubsequently trimmed from the part. However, this



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material provides a convenient demolding tab.Wedge tools are inserted between the mold flangeand this offage, producing a lifting force that servesto begin the demolding event.

When the newly designed closed mold systemfeatures reinforcement that ends at the flange insideedge, there is no longer a ‘flange laminate’ that canbe used as a demolding tab. When mold releaserequires mechanical assistance, wedges placedbetween the mold flange and the resin that filled theedge manifold easily break off the unreinforced resinwithout generating adequate lifting force to effect thepart removal. Then, when wedges are placedbetween the mold sidewall and part, the forces aremostly in the horizontal direction, not in the verticallifting direction. Although demold can be achieved inthis manner, the more common result is gel coatscarring near the boundary of the edge manifold.This becomes progressively worse throughout themold service life.

A fiber-reinforced demolding tab can be incorporatedin the molded part by extending the part surfaceupwards and outwards as shown in Figure 5/V.5. Asimple bevel at 45 degrees from verticalaccomplishes this with little added cost to toolingand part manufacture. The upper transition, from thediagonal to the horizontal, also provides an accurateguide for cutting the dry glass. This provides forconsistency in the perimeter edge manifold width,with resultant increases in fill consistency.

E. Closed Mold Sealing Issues—A rubberextrusion seals against a physical surface by beingcompressed against the surface. One way toachieve this is to use a solid rubber profile that iscompressed by moving the mold pieces together.This contact is best accomplished by moving thesurfaces together in purely a perpendicular fashion.The initial contact occurs before the mold pieces arecompletely together. As the mold pieces are broughtinto contact, the seal is compressed.

When two mold pieces come together, there are twocomponents to the motion. One is perpendicular tothe surface while the other is parallel to the surface.Problems arise when bringing the surface and theextrusion into contact by motion that includes a

Figure 5/V.5 - Extended te part so that there isa one

inch long bevel at 45 degrees. This replaces the open

mold flange laminate with a reinforced tab that assists in

demolding when wedges are used.

parallel component. From the time when contact isfirst established until the seal is compressed, theparallel motion serves to drag the seal extrusion.Best results are obtained when the contact surfacesmove together in purely a perpendicular fashion.Another method uses a hollow rubber profile that fitsin a seal groove and is expanded by pressure oncethe mold pieces are assembled. Tucked inside theseal groove, the parallel motion cannot drag the sealextrusion.

F. Resin Transfer Ports, Manifolds and Ventsfor Shell Laminate RTM—Proper, symmetric moldfilling is almost always best achieved with twoinjectors and one vent. These injectors will be calledthe ‘primary’ injectors. The resin is supplied to theentire part perimeter via the edge manifold. Theresin flow will converge on the vented flow center.The flow center depends on the planform (theoutline of an object when viewed from above) andthe thickness. For a single cavity thickness, the flowcenter is in the planform center. If half the part istwice as thick, the flow center is skewed towards thethick area, because it takes more resin to fill up thegreater thickness. The vent should always belocated at the flow center.

The injectors are positioned by finding the ‘longeststraight line distance across the part.’ For certainodd part shapes, this ‘straight’ line may be ‘bent’ atone or more locations. Measure a path across thepart with a cloth tape measure (available in the



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sewing aisle at grocery or discount stores) until youidentify the longest straight line path. The vent isalmost always along this path. If the thickness is notconstant, or if there is more part to one side of thisline, the line will move in a parallel sense toward the‘thicker’ or ‘bigger’ area. ‘Thicker’ is relative to‘longer’ when it comes to the path because it takesmore resin to fill up the thicker cavity. The two

Resin Transfer Ports, Manifolds and Vents forShell Laminate RTM continued:primary injectors are positioned at the part perimeterat these points.

For large parts, or extremely odd shapes, twosecondary injectors may be used. These injectorsare located midway between the primary pair ofinjectors. With a consistently thick part, thesecondary injectors would be placed exactlybetween the two primary injectors. For parts withvarying thickness, the secondary injector would beskewed towards the thicker portion of the part.

If parts are much longer than they are wide,secondary injectors are not used until later in the fillprocess. The delay time depends on the length-to-width ratio. The longer it is to wide, the longer thesecondary injectors are delayed.

Certain part designs require a second resinmanifold, a portion of the way from the edgemanifold to the flow center. The edge manifold isused to fill the part until the resin reaches the innermanifold. Then, resin flow is directed through theinner manifold until the part is completely full. This isnecessary for large parts, parts with high glasscontents, or parts with heavy filler loadings and thus,higher viscosity matrix material.

G. Examples of Injector and Vent Locations—

1) Example: Part #1 is a perfect square ofuniform thickness. The longest straight-linepath across the part is on the diagonal. Twoinjectors are located on opposite corners.The vent is located midway between theinjectors, at the center of the square. Mostoften, the injectors are mistakenly placed atthe middle of a side.

2) Example: Part #2 is a long rectangle ofuniform thickness. The longest straight-line

path across the part is on the diagonal. Twoinjectors are located on opposite corners.The vent is located midway between theinjectors, at the center of the rectangle.

3) Example: Part #3 is a perfect circle ofuniform thickness. The longest straight-linepath is any one of the diameters. Theinjectors are located at both ends of thediameter and the vent is in the center.

5. PATTERNING THE UPPER MOLD—There arethree methods of patterning the Upper Mold geometry.Each can produce the necessary upper mold, althoughwith varying results.

A. Machining from Tooling Block—The highestdegree of accuracy is achieved with a computer-controlled cutting machine. Solid modelingtechniques are used to produce a computer aideddesign (CAD) /computer aided manufacturing (CAM)data file that is used to control a numericallycontrolled (NC) cutting machine. A plug blank is firstconstructed from tooling block or other patternmaterials.

B. Calibrated Sheet Pattern Materials—Thelower mold can also provide the basis for the uppermold geometry. Pattern materials are placed into thelower mold to simulate the part thickness. Calibratedthickness sheet wax provides a high degree ofaccuracy. Other pattern materials can be used,particularly in thick areas. Mold features such as theedge manifold and vacuum clamps are alsopatterned upon the lower mold. This master plugthen provides the surface definition for the uppermold.

C. The Master Part—A master part can beconstructed using either hand lamination or vacuuminfusion. The lower mold is used for this method.Careful attention to glass content is required toensure accurate mold cavity thickness. Inside edgestend to be thicker than intended for hand laminatedparts. Some amount of grinding may be necessaryto achieve back side radius requirements. The entirepart surface must be coated with a filler type primermaterial and finished smooth for molding the uppermold. This method does not provide the sameaccuracy as the other methods presented.



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6. CLOSED MOLD FABRICATION—Most patterns arenot durable and are suitable for only one pull. Thedemold process usually imparts sufficient forces todestroy the pattern. As a result, two options presentthemselves for consideration. Either one accurate uppermold can be built from the pattern, or a robust masterwith accurate upper mold geometry can be built thatcan yield any number of high accuracy upper molds.

CLOSED MOLD FABRICATION continued:In almost all cases, a Zero mold should be made fromthe pattern. This Zero mold is so named because it isused as a step in the production of tooling. It has thegeometry of the upper mold, but is not the sameconstruction. The Zero mold should be constructed in amanner similar to a conventional open mold. Steelframing is preferred but wood is acceptable whenencapsulated in glass laminate. A fiberglass MasterMold is made from the Zero mold. The production moldsare made from the fiberglass Master Mold. In thismethod, accurate upper mold geometry has beenmaintained through the successive moldings.

A common mistake is to forgo the master building stepand build the upper mold directly from the pattern. Theshell laminate upper mold can be easily warped orcracked during use as an RTM mold. When thishappens, geometric accuracy is lost. Any masterproduced from a warped/cracked shell laminate uppermold will not have the correct geometry, consistent moldfill performance, or accurate part thicknesses andweights. The only recourse is to repattern the uppermold using the lower mold as a basis. This requires thatthe lower mold be taken out of production for one to twoweeks for the mastering process. With a high qualityfiberglass master, a new shell laminate upper mold canbe produced in two days time while the current mold setis still in production.

7. UPSTREAM PROCESSES—Processes that occurupstream of the liquid injection procedure reduce lowermold productivity when the mold is engaged in thatactivity. These processes can include taping/masking,applying and curing gel coat and loading thereinforcement materials. Multiple lower mold pieces canbe used to address the need for Work In Process (WIP)at each operation.

For conventional RTM, the lower mold tooling costbecomes prohibitive when gel coat is an upstream

operation. The benefits of rapid cycling disappear, andthe need for high pressure injection wanes.

8. EXECUTING THE CLOSED MOLD PROCESS—During the course of building parts, certain actions canhave undesirable effects. These effects can gounnoticed, or their causes can be unknown. Regardless,bad habits during process execution usually addsproduction cost.

A. Resin Transfer—The proper amount of resinmust be transferred to the closed mold cavity. This isbest accomplished with a resin pump thatautomatically shuts off after pumping the desiredquantity of resin. For both the Shell Laminate RTMand Silicone Bag RTM processes, the mold cavitiesare full before they appear to be full. Resin pressurelifts the upper mold slightly as the mold fills. Whenthe proper amount of resin is transferred, the ventvacuum causes the upper mold to return to itsdesign height as the resin reaches the vent location.Properly executed, very little resin exits the moldcavity at the vent location.

Transferring the proper amount of resin isparticularly important for Shell Laminate RTMprocess. The resin flows from the perimeter edgemanifold and converges on the vacuum vent at theflow center. As the fill process begins, there is nohydrostatic pressure on the resin flow front in theunobstructed flow channel. As the resin begins tomove into the glass pack, the pressure increasesaccording to the distance traveled through the glasspack and the rate of resin delivery. The pressure ishighest at the edge of the part and lowest at the flowfront. The pressure forces the upper mold to moveupwards, producing a thicker mold cavity thatrequires more resin to fill. If resin pumping continuesuntil the resin enters the vent trap, the pressures risevery quickly due to the small vent diameter relativeto the large injector diameter. Usually, the higherexotherm temperatures experienced in the greatermass will cause the upper mold to take a permanentset. When this occurs, part thickness is permanentlyimpacted for this mold set.

B. Vacuum Leakage—Whenever vacuum isapplied to the mold vent, the mold set must bevacuum tight. Minor vacuum leaks are the rootcause of most problems encountered when



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developing a closed mold system that featuresvacuum venting. These problems produce parts withdry spots and air voids. Vacuum integrity is one ofthe more difficult concepts for open mold techniciansto appreciate, particularly when the vacuum leakageis through the mold laminate. On the other hand,technicians working with high pressure (i.e.,autoclave) lamination processes quickly learn torespect leakage through the mold laminate.

Vacuum Leakage continued:1) Measuring Vacuum Leakage for the Closed

Mold Set—A vacuum gauge is required todetermine minor vacuum leakage rates.First, vacuum is applied to the mold set. Thelevel of vacuum is noted. The vacuumsource is interrupted and the time interval ismeasured. After a prescribed time, the levelof vacuum is again noted. The differencebetween the initial vacuum and the vacuumafter five minutes corresponds to the overall

vacuum leakage rate.

For a very tight mold, vacuum will holdsteady during the entire five-minute test. Aleak-down of 0.5 to 1 inch of mercury isconsistent with a well sealed mold. Even thislevel can make part manufacture difficult forhigh vacuum processes. For leak-downrates from 1 to 2 inches of mercury, mostparts can be successfully fabricated. For aleak-down exceeding five inches of mercuryin 5 minutes, successful part manufacture isdifficult, if not impossible, even if vacuum isvented before resin gellation.

It is vitally important to have a leak-freemold. To ensure the vacuum integrity, aleak-down test must be performed on everynew mold set. Since there are two separatecavities in the Light RTM mold, the leak-down test should be performed twice: onceon the clamp chamber, and once on the partcavity.

First, ensure that both molds have aserviceable coating of release agent. Loadthe glass and cores into the lower mold.Prepare the upper mold by installing a newinjection tube. Position the upper mold upon

the lower mold. Install the resin trap at thevent location. Clamp off the injection tube.Apply a full vacuum to the clamp chambervia the clamp fitting. Apply half vacuum tothe part cavity via the resin trap. If the moldset does not close and seal, apply a manualforce to the upper mold until the flap sealcontacts the lower mold flange. Once theflap seal is established, the upper mold willdraw towards the lower mold until the innerseal comes into contact with the lower moldflange.

Vent the vacuum connection to the partcavity by disconnecting the line to the resintrap while maintaining the vacuumconnection to the clamp chamber. The innerseal should allow the clamp to maintain aclosing force between the mold halves.

Interrupt the vacuum supply to the clampcavity without venting the clamp toatmosphere. Monitor the level of vacuumpresent in the clamp cavity as time passes.The clamp should maintain enough vacuumto remain clamped for 30 minutes or longer.If the clamp does not maintain vacuum verylong, there is a leak. It may be necessary tofind and repair this leak.

Once vacuum integrity has been establishedfor the clamp chamber, apply vacuum to thepart cavity. At this point, both the clamp andthe part cavity are under vacuum. After afew minutes, interrupt the vacuum supply toboth the clamp and part cavity. Monitor thelevel of vacuum present in the part cavity astime passes. The part cavity should maintainvacuum for 30 minutes or longer. If the partcavity does not maintain vacuum very long,there is a leak. It is probably necessary tofind and repair this leak.

Some leaks are not harmful. If the clampleaks, and if that leak is NOT across theinner seal, and if the vacuum system cankeep ahead of the leak, successful moldingis possible. If the part cavity leaks, and ifthat leak is right at the resin trap ventlocation, successful molding is possible.



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If, however, the part cavity leaks, and if theleak’s location is away from the ventlocation, the vent vacuum will draw air intothe part, and the displaced resin willaccumulate in the resin trap. A large leak willallow most of the resin to exit the part via thevent fitting. If the resin trap overflows, resinwill enter the vacuum system and requireimmediate removal.

Vacuum Leakage continued:2) Vacuum Leakage through Laminate Porosity

in the Closed Mold Skin—All laminatescontain some amount of porosity or micro-porosity. When this porosity is great enough,atmospheric air will leak into the mold cavityby traveling through the porous laminate.

Of all the possible leakage paths, this one isthe most difficult for process engineers tocomprehend. A simple experiment can beperformed to show this phenomenon. Theexperimenter should build two vacuum bags.One vacuum bag should be on the moldside of a porous laminate. The other vacuumbag should be on a glass plate. Eachvacuum bag should be equipped with both avacuum gauge on the resin feed line, and onthe vent line, a vacuum source that can beinterrupted without venting the bag toatmosphere.

Perform a vacuum leak-down test on bothvacuum bags. The vacuum bag on the glassplate serves to demonstrate that the studentcan successfully build a good vacuum bagwhich maintains vacuum for a long time.

If the mold skin porosity is resulting invacuum leakage, successful partmanufacture may not be practical.

3) Resin Outgassing—During resinmanufacture, air is introduced into the resinduring blending operations. This airdissolves into the resin in the same way thatcarbon dioxide dissolves into water to formthe fizz in carbonated beverages. Reducingthe pressure above the solution andincreasing its temperature provides a drivingforce which forces the dissolved gases out

of solution in the form of bubbles.

During the resin transfer operation, appliedvacuum first acts to degas the resin, pullingdissolved air out of the resin solution. It isnormal for bubbles to form at the resin flowfront. Many times this is mistakenlyattributed to ‘styrene boil.’ Instead, thesebubbles are largely due to degassing.

Vacuum does not draw air bubbles ‘through’the resin. On a sealed system, vacuum willcause the air bubbles to become larger inaccordance with Boyle’s Law. Applyingvacuum to the vent merely increases thepressure head that forces the resin to flowthrough the mold cavity. Air bubbles movethrough the mold cavity by virtue of beingcarried by this resin flow. Any air in thesystem must exit during the resin transferoperation. Problems arise when air entersthe system late in the fill process. Theremust be enough resin flow to carry thebubbles to the vent. This requires that moreresin enters the mold cavity.

C. Downstream Impacts—Operations that occurdownstream from the closed mold process can beaffected by changes in the part that directly resultfrom the change to closed molding.

1) Open Mold Tabbing—Open mold tabbing isthe process of affixing a secondarystructural element to a previously laminatedpart using open mold laminating techniques.This is a secondary lamination process.Secondary lamination requires that theunderlying surface is not fully cured and notextremely smooth. Timing is the keyparameter. The underlying part is allowed togel and cure to some extent. To achieve agood secondary bond, the secondarylaminate must be applied before the partcures too much.

If too much time elapses, then the partsurface must be mechanically abraded priorto applying the secondary laminate. Thisprocedure removes contaminates as well asprovides a mechanical ‘keyway’ for thesecondary laminate adhesion. An alternative



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to mechanical abrasion is the use of a peelply. The peel ply produces a texturedfracture surface when it is removed from thecured part.

There are two components to secondarylaminate adhesion. One is a chemical bondwith resin unsaturation in the underlyingpart. The second is a mechanical bond due

Downstream Impacts continued:to the surface roughness on the underlyingpart.

To understand the importance of mechanicalbonding, consider the following scenario.Select a well-cured substrate comprising amolded surface with exterior gel coat. Onone half of the substrate, do not perform anysanding; this will be called the smoothsubstrate. On the other half of the substrate,lightly sand the gel-coated surface with anaggressive sandpaper, such as 60 grit, untilthe gloss is removed and the surface iscovered with sanding scratches; this will becalled the sanded substrate. Solvent-wipethe surface to remove all traces of dirt andcontaminants from both halves of thesubstrate. Apply a nominal thickness (1/4 to1/2 inch thickness) of catalyzed polyesterbonding putty to each half of the substrate.Allow the bonding putty to cure. Evaluate thebond quality by using a putty knife to pry thebonding putty from each half of thesubstrate. The putty on the smooth gel coatsubstrate will release with much less effortthan the putty on the sanded gel coatsubstrate. The difference is due entirely tothe mechanical keyway provided by thesanding scratches. In this case, both pieceswere equally well cured and not subject tooxygen inhibition as is the case with a backside open mold laminate.

2) Adhesive Bonding—The substrate surfacefeatures will determine the appropriate typeof adhesive to use for successful bonding.Some adhesive types contain an etchingagent that enhances the adhesion onsmooth, gel-coated surfaces. Alternatively,

some adhesive systems use a primer wipeto soften the substrate prior to bonding.Methacrylate adhesives are becomingincreasingly popular as a replacement foropen mold tabbing.

D. Conclusions—Variations of the RTM processare suitable to replace open mold lamination.Attention to detail is a key ingredient to the successof transitioning. Building an accurate mold cavity thatis free from vacuum leaks is the pertinent challengefor Shell Laminate RTM and Silicone Bag RTMprocesses.

For rigid upper mold types, the fabrication of theupper mold must follow successful prototyping toinclude the ply kit and lamination schedule (not justin regard to fit and form, but also function).Designing the ply kit prior to the upper mold providesfor the most economical part material usage. Theupstream process of gel coating has a distinctimpact on the economics of conventional RTM dueto the time involved with applying and curing the gelcoat. The downstream processes of secondarylamination and adhesive bonding must also beexamined for suitability with a given closed moldprocess due to the different nature of smooth,molded surfaces.

E. Appendices—The following sections provideadditional information that many consider useful.

1) Flow Theory—Flow through porous mediacan be described mathematically. A Frenchcivil engineer in the mid 1850s formulated arelationship known as Darcy’s Law. Thisrelationship is:

Q = -KA dh/L Rate of Fluid FlowQ is the rate of fluid flowK is the hydraulic conductivityA is the cross sectional area of theporous mediumdh is the change in pressure over thelength L

L is the path lengthThis equation shows that which is intuitivelyobvious. The flow is quicker when thehydraulic conductivity is greater, when theflow area is greater, when the pressure dropis greater and when the fill path is shorter.



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Rapid fluid flow requires greater hydraulicconductivity, larger flow area, largerpressure drops and shorter fill lengths. Theflow is slower when the hydraulicconductivity is lower, the flow area issmaller, the pressure drop is lower and thepath length is longer.The hydraulic conductivity is also known asthe permeability. This permeability is greater

Appendices continued:when the fiber is less compacted.Conversely, when the fiber is highlycompacted, the permeability is low, and flowis reduced. The orientation and arrangementof fibers in the reinforcing pack will alsoaffect the permeability. These features arereferred to as the fiber pack architecture.

To expand on Darcy’s Law further anddefine the hydraulic conductivity K:

K = (Intrinsic permeability)*(fluiddensity)*(Acceleration due togravity)/(fluid viscosity)

The intrinsic permeability of the porousmedia is the property determined by thereinforcement form and its degree ofcompression. A lower fluid viscosity causesan increase in the hydraulic conductivity witha corresponding increase in the rate of fluidflow.

The two resin properties of interest, densityand viscosity, are both functions oftemperature and degree of cure. As a moldfills, the viscosity increases until gellationoccurs.

2) Shell Laminate Mold Design Checklist

Lower Mold:

—Does my lower mold have features thatallow me to wedge out a stuck part withoutcausing damage to the mold surface?

—Is the boundary of the edge manifoldeasily identified to enable accurate materialtrimming?

—Is my flange design appropriate for myseal rubber extrusions?

—Will the upper mold fit in only one clockposition?

—Does my mold set come together andseparate with a pure vertical motion?

Upper Mold:

—Have I designed and proven my part?

—Have I designed my ply kit so that I knowwhere my overlaps will be?

—Have I chosen cavity thicknesses thatcorrespond to the materials and glasscontents specified by the proven design?

—Have I identified the flow center andinjector locations?

—Does my mold set have alignment devicesthat align the mold set before the partfeatures force the molds to align?

—Does my mold set have features thatallow me to wedge the upper mold off thepart/lower mold without destroying myrubber seal extrusions?

3) Shell Laminate RTM

Step-by-Step Process Description:

—Mask the lower mold flange at the flapseal for gel-coating. Apply gel coat.

—Load the cavity with specified glass andcore.

—Trim reinforcement at the edge manifold.

—Place Upper Mold approximately inposition.

—Install and clamp the injector tube(s).

—Install the vent line or resin trap.

—Apply vacuum to the part cavity at thevent first. Apply hand pressure to bring theouter flap seal into contact with the lowermold.

—Apply vacuum to the clamp cavity onceouter seal integrity is established.

—Vent the part cavity to check the innerseal.

—Reapply the vacuum supply to the part



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cavity. Perform Leak-down Test.

—Transfer the proper amount of resin intothe part cavity. Clamp off the injector tube.

—Maintain vacuum on both the part cavityand clamp cavity until the resin gels.

—Once the resin gels, remove the resin trapand clean immediately.

Appendices continued:—Maintain vacuum on the clamp chamberuntil the part cures sufficiently to meet thepart and process design requirements.

—Remove the upper mold. Perform moldmaintenance immediately.

—Allow the part to continue curingsufficiently to meet the part and processdesign requirements. Remove the part.

4) What makes a good Shell Laminate RTMmold design?

A properly designed and built Light RTMmold has certain features:

—The mold set is vacuum tight.

—The upper mold cannot accidentally beinstalled at the wrong clocking relative to thelower mold. If the lower mold is oriented at12 o’clock, it is not possible to close themold at any orientation other than 12o’clock.

—Alignment devices align the mold setbefore the part’s geometry does.

—The mold can be assembled and sealedusing only moderate hand pressure and thevacuum clamps, without resorting tomechanical clamps.

—The fill is consistent from part to part.

—The glass is not so compressed as toprevent fiber wet out.

—A known amount of resin is transferred tothe part cavity and very little (tablespoons)makes its way into the vacuum trap.

—The molds separate with a true verticalmotion.

—It’s easy to wedge the upper mold off thelower without damaging the rubber sealextrusions.

—It’s easy to wedge the part off the lowermold without damaging the lower mold gelcoat surface.

9. A DISCUSSION OF VACUUM—Vacuum bags workby using the Earth’s atmosphere to provide a force. Theweight of the Earth’s atmosphere amounts toapproximately 14.7 pounds per square inch. Whenever avacuum is applied to a closed cavity, the Earth’satmosphere can apply up to 14.7 pounds per squareinch against the outside walls of the closed cavity. This14.7 pounds per square inch is for a full vacuum atstandard temperature and pressure (STP). STP isdefined by scientists to be 77°F (25ºC) at sea level and

will produce approximately 14.696 psi of normalatmospheric pressure.

Vacuum is not an entity or a thing. It is just a pressurethat is lower than normal atmospheric pressure.Pressure is a scale much the same as temperature; bothindicate how much of something is present. Pressureindicates how many gas molecules are contained in acertain volume at a certain temperature. If there are zerogas molecules in a volume, there is zero pressure. Thereis no such thing as negative pressure. Pressure can onlybe positive or zero. The amount of vacuum can vary, butthere is a maximum value of 14.7 psi vacuum. This is anaverage number; the exact maximum depends on one’saltitude and weather conditions (current barometricpressure).

Consider an ‘empty’ open container at 77°F (25ºC), atsea level on a standard Earth day. Close it and seal it. Itwould contain some number of gas molecules at oneatmosphere of pressure, which is the same as 14.7pounds per square inch absolute (psia) pressure. SinceEarth’s atmosphere is one of pressure, 14.7 psi absolute(psia) pressure is considered to be the same as zero psigauge (psig) pressure. Zero psi gauge pressure meansthe gas is not compressed any more than it already is inthe surrounding air. To convert, take absolute pressureand subtract 14.7 psi to get gauge pressure; conversely,one would take gauge pressure and add 14.7 psi to getabsolute pressure. Most times, the word ‘gauge’ is leftoff, much the same as the words ‘per square inch’ areleft off when it is said that ‘The tire takes 35 pounds of



Page 13 of 16


air pressure’; neither is technically correct but both areused widely as an abbreviation.

Taking that same container of air, consider removingsome portion of the air molecules. This would cause thepressure in the container to drop lower than the 14.7 psiabsolute. For instance, the new pressure in the containermight be 9.7 psi absolute. The amount of vacuum is thedifference between the normal atmospheric pressure

A DISCUSSION OF VACUUM continued:and the actual absolute pressure. In this case theamount of vacuum is 14.7 minus nine = 5 psi vacuum. Inthis example, the Earth’s atmosphere is now exerting 5psi of force on the outside of the container’s walls. If onewere to pump out all the air, one would have a fullvacuum. A full vacuum is zero psi absolute, which is thesame as 14.7 psi vacuum, which is the same as minus14.7 psi gauge pressure. Notice that the gauge pressureis a negative number in this example. It is not a negativepressure. It is a negative number because we took theactual pressure, which was zero psi absolute andsubtracted one atmosphere’s worth of psi.

The amount of vacuum is generally not expressed interms of pounds per square inch. Usually, vacuum isreferred to as ‘inches of mercury.’ Even though vacuumis widely used, most people don’t care how muchvacuum they have as long as they have enough.Originally, most of the people who cared how muchvacuum they had were scientists. In the laboratory,scientists can make a very accurate vacuum gauge withordinary lab items. These simple gauges read vacuum in‘inches of mercury.’ Since commercially manufacturedgauges were originally sold mainly to the scientists, theyused the same ‘inches of mercury’ scale of vacuum. Onthe other hand, the earliest compressed air gauges wereused by engineers who made tools and other things thatwork with air pressure. These gauges have the units ofpound per square inch because square inches are easyto measure, and calculating the force is simplymultiplying the pounds per square inch (psi) times thesquare inches that the pressure is acting upon.

To understand inches of mercury, consider a U-shapedtube that is filled with mercury, with both ends pointingupward and open to the atmosphere. The mercury in theleft side of the U is at the same height as the mercury inthe right side of the U. Now, keep the left side of the Uopen to the atmosphere. Connect the right side of the U

to a full vacuum. There is a certain amount of ‘pull’ to avacuum. The atmospheric air pressure pushesdownward on the mercury in the left side of the U. At thesame time, there is a full vacuum pull on the right side.Since there is only a certain amount of vacuum pull, themercury goes downward in the left tube, upward in theright tube until it balances out. Now the mercury in theright and left tubes are at different heights. If onemeasured the distance between the two, it would be30.00 inches of mercury from a full vacuum. A partialvacuum is any amount of vacuum that is less than fullvacuum.



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Page 15 of 16







Page 16 of 16

COMPRESSION MOLDING: Introduction


Part Six, Chapter ICopyright 2008

In Part SixChapter I: Introduction

Chapter II: Materials and Typical Compound

Formulations

Chapter III: Compounding Processes and

Equipment

Chapter IV: Molding Processes and Equipment

Chapter V: Troubleshooting

Compression molding involves molding apremanufactured compound in a closed mold underpressure and often using heat.

Typical compression molding applications include:

• Appliance housings• Automotive body panels and structural parts• Basketball backboards• Cafeteria trays• Door skins• Furniture• Electrical circuit boards and boxes• Personal water craft• Satellite dishes• Shower/tubs and sinks• Utility boxes

A premanufactured compound is a combination of someor all of the following: thermoset resin, catalyst, moldrelease, pigment, filler, various additives, and fiberreinforcement.

Compounds can be produced in several forms, includingsheet molding compound (SMC), bulk moldingcompound (BMC), and wet molding compound.

Two additional compound forms are Low PressureMolding Compound (LPMC) and Low Pressure, LowTemperature Molding Compound (LPLTMC). Thesecompounds can be either in sheet or bulk form but arespecially formulated to allow molding at lower pressuresand/or lower temperatures than conventional SMC andBMC. Lower molding pressures mean lower presstonnage requirements, which reduces the capitalexpense for a new press or increases efficiency of anexisting press. Lower molding pressures can also meanlower tooling costs since materials other that tool steelcan be used. Lower molding temperatures can result inlower tooling costs and lower energy costs.

The table below compares the various types ofcompounds:



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COMPRESSION MOLDING: IntroductionCopyright 2008

Property Sheet Molding Compound (SMC) Bulk Molding Compound (BMC) Wet Molding

Compound

Part cross-

section

Complex Complex Uniform

Parts per eight-

hour shift

100-500 100-1000 (could be higher if

multiple cavity molds used, i.e.,

dishes or electrical outlet boxes)

50-100

Compounding

equipment

SMC machine and required mixingand dispensing equipment

BMC mixer Mixer

Time required

for maturation

after

compounding

2-5 days 0-2 days None

Glass type Normally chopped, but may includeunidirectional or rolled/mat products

Chopped Preform or rolled/matproducts

Mold charging Charge weight and geometry arepredetermined. Charge cutting andloading is done manually or bycomputer- controlled slitting andloading.

Various (manual, injection or

transfer)

Place preform in moldby hand and pourresin over

Molding

temperature

Conventional: 270-320°F (132-

160°C)

Low temperature: 180-220°F

(82-104°C)

Conventional: 270-320°F (132-

160°C)

Low temperature: 180-220°F

(82-104°C)

Room temperature to

300°F (149°C

Molding

pressure

Conventional: 500-3000 psi

Low pressure: 50-200 psi

Conventional: 500-3000 psi

Low pressure: 50-200 psi

<50 psi

Mechanical

properties

Good to high (with roll good or

unidirectional fibers)

Low High



Page 2 of 4



Page 3 of 4







Page 4 of 4

COMPRESSION MOLDING:

Materials and Typical Compound Formulations


Part Six, Chapter II

Copyright 2008

In This Chapter1. Resins

2. Shrinkage Control Additives

3. Catalysts

4. Inhibitors

5. Pigments

6. Mold Release

7. Filler

8. Thickeners

9. Fiber Reinforcement

10. Specialty Additives

11. Typical Compound Formulations

1. RESINS—Unsaturated polyester resins (UPR) arethe basis for most compression molding compounds.The type of UPR used varies, depending on theperformance requirements for the finished part and cost.Resins used for compression molding can be broken intofour broad categories:

• Structural Resins—isophthalics, terephthalics,and urethane hybrids

• Low Profile Resins• General Purpose Resins—orthophthalic or

dicyclopentadiene• Specialty Resins

Structural resins are used in applications requiringexcellent mechanical properties and/or temperature andchemical resistance. Low profile resins are used inapplications requiring excellent part appearance,dimensional stability, or class A surface profile, such asautomotive body panels. Low profile resins arecharacterized by high reactivity rather than polymer type.General purpose resins are used in applications that arecost-sensitive and have more lenient part performancerequirements than structural or low profile applications.

Specialty resins are designed for very specificapplication requirements, such as weather resistance orflame retardancy.

2. SHRINKAGE CONTROL ADDITIVES—Unsaturatedpolyester resins shrink 3 to 7 percent by volume duringcure. This shrinkage can create a variety of defects inmolded parts, such as surface distortion, waviness, fiberprint, and warpage. Shrinkage of unsaturated polyesterresins can be controlled by the use of shrinkage controladditives. However, use of shrinkage control additivescan reduce mechanical properties. Shrinkage controladditives can be divided into two categories: low shrinkadditives and low profile additives.

A. Low shrink additives minimize shrinkage butdo not eliminate it. Low shrink additives are used inapplications with lenient surface appearance anddimensional stability requirements. Low shrinkadditives are especially useful in applicationsrequiring pigmentation. Common low shrinkadditives are polystyrene, polymethyl methacrylate,and rubber elastomers.

B. Low profile additives, when used atappropriate levels, eliminate shrinkage and can evenresult in slight expansion. Low profile additives areused in applications requiring excellent surfaceappearance and dimensional stability, such asautomotive body panels. Molding compoundformulations using low profile additives have limitedpigmentability, generally white or light pastel colors.Common low profile additives are saturatedpolyesters and polyvinyl acetate.

Blends of low shrink and low profile additives arefrequently used to impart the benefits of both typesof additives to the molded part.

3. CATALYSTS—Catalysts or peroxide initiatorsinitiate the chemical reaction of the UPR and monomer.For elevated temperature processing the heat from themold causes the catalyst to decompose, initiating the



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COMPRESSION MOLDING: Materials and Typical Compound FormulationsCopyright 2008

CATALYSTS continued:reaction. For ambient or low temperature processing, apromoter or a combination of promoters is needed toaccelerate decomposition of the catalyst. Typicalpromoters are cobalt and amines. Catalyst selectiondepends on the molding temperature. Some commoncatalysts and their molding temperature ranges aregiven in the following chart. Two or more catalysts areoften used to ensure complete cure.

Catalyst Type Processing Temperature

Range °F (ºC)

Benzoyl peroxide

(BPO) and amine

promoter

90-120 (32-49ºC)

Benzoyl peroxide

(BPO)

180-250 (82-121ºC)

Tert-butyl peroxy-2-

ethyl hexanoate (PDO)

220-280 (104-138ºC)

Tertiary butyl

perbenzoate (TBPB)

250-320 (121-160ºC)

4. INHIBITORS—Inhibitors are used to controlcompound shelf life and cure rate. Two commonly usedinhibitors are butylated hydroxy toluene (BHT) and para-benzoquinone (PBQ). BHT has little effect on elevatedtemperature cures but does significantly lengthen roomtemperature shelf life. PBQ lengthens both roomtemperature shelf life and cure time.

5. PIGMENTS—Many, but not all, molding compoundsare pigmented, and a broad range of molded-in colorscan be achieved. However, some limitations on color doexist. Fillers used in compression molding compoundscan add color to the compound and limit the possiblecolors of the molded part. Also, the type of shrinkage-control additive used can limit color possibilities.Generally, darker and richer colors are more difficult toachieve. Darker colors can shift hue duringmaturation/aging.

Pigments are added during compound manufacture ineither powder or predispersed paste form. Powder

pigments can be difficult to disperse in the compounddue to agglomeration. Predispersed pigment pastes areeasier to disperse and can be used at lowerconcentrations than dry powders. Common whitepigments are titanium dioxide and zinc sulfide. Carbonblack is often used for black pigmentation. Pigmentpaste dispersions generally consist of the pigmentdispersed in an unsaturated polyester grinding vehicle.Pigments can affect the shelf stability and reactivity ofmolding compounds.

6. MOLD RELEASE—Compression moldingcompounds generally contain internal mold release.Some of the most commonly used internal mold releasesare zinc stearate and calcium stearate. Liquid mold-release additives are also available. Use of theseadditives results in much lower SMC paste viscosity thanthat obtained with stearates.

7. FILLERS—Compression molding compounds, withthe exception of those used to mold parts for structuralapplications, are highly filled. Fillers lower material costswhile enhancing molded part appearance, reducingshrinkage, promoting the flow of glass reinforcementduring molding, and contributing to a harder, stiffer part.However, fillers increase the viscosity of moldingcompound paste, limiting the amount of glass that canbe used. Glass content is directly related to themechanical properties of the molded part with higherglass contents yielding superior mechanical properties.Fillers also provide opacity and increased part density.The most common fillers are calcium carbonate, clay,and alumina trihydrate. Clay fillers are used inapplications requiring resistance to acid. Clay fillers areoften used in combination with calcium carbonate fillersto control the compound paste viscosity, promote flow,and improve crack resistance in molded parts. Aluminatrihydrate is generally used in applications requiringflame retardancy and/or good electrical properties.

8. THICKENERS—Thickeners are used in sheetmolding compound (SMC) to transform the material intoa manageable, reproducible molding material.Thickeners chemically react with the resin portion of thecompound, resulting in an increased viscosity.Thickeners are the last component added to thecompound paste and begin to react immediately afteraddition.



Page 2 of 7


THICKENERS continued:Typical thickeners are alkaline earth oxides orhydroxides such as MgO, Mg(OH)2, CaO, and Ca(OH)2.MgO provides the quickest thickening of those listed andis the most commonly used thickener. Thickeners aresometimes used in combination to achieve a particularthickening profile. Thickeners can be added as a powderor predispersed paste. As with pigments, predispersedpastes are easier to disperse in the compound andgenerally result in more consistent thickening.

A typical thickening profile is described in terms of paste(all ingredients except reinforcement) viscosity. Duringcompounding, the paste viscosity must be low enough toallow for pumping and reinforcement wet out.Compounding is generally accomplished in less than 30minutes from the time of thickener addition. Initially(immediately after thickener addition), paste viscositiesare 10,000 to 60,000 cps (similar to thick pancakebatter). The paste viscosity typically increases to300,000 to 1 million cps (similar to pudding) in the first60 minutes. After compounding, the material is moved toa maturation room, typically maintained at 90°F (32º),until it reaches its release viscosity. At the releaseviscosity, the compound has the required characteristicsto allow it to be molded. These characteristics includethe following:

• The compound must be manageable toallow for charge preparation.

• The viscosity must be high enough to carrythe fiber reinforcement as the material flowsin the mold.

• The viscosity must be low enough to permitsufficient flow for mold filling at reasonablemolding pressures.

The release viscosity is typically between 10 to 30 MMcps (similar to bread dough) and is achieved in one tofour days. The viscosity of the material continues toincrease even after it has reached its release viscosity.The rate of this increase determines the molding windowof the material. SMC may be moldable up to 100 millioncps, depending on part complexity and moldingpressure. Factors affecting thickening of a SMCformulation include thickener type and level, the acidvalue of the UPR, molecular weight of the UPR, andwater content of the compound.

9. FIBER REINFORCEMENT— Many types of fiberreinforcements, including glass, carbon/graphite, andaramid, can be used in compression molding. The mostcommon fiber reinforcement in compression molding isglass. Various forms of glass fiber are used, dependingon the type of compression molding compound beingproduced and molded. Chopped fibers ranging in lengthfrom 1/8 inch to 1/2 inch are used in bulk moldingcompounds. Continuous rovings are used in SMCproduction. The roving is chopped to 1/2 inch to 2-inchlengths during the SMC compounding process. Themost common length of glass fiber for SMC is 1 inch.

Glass fiber preforms, made to the general size andshape of the part, are used for wet molding and coldmolding. For these processes, the glass and compoundpaste are combined during molding rather than duringcompound manufacturing as for BMC and SMC. Pleaserefer to Part Five, Chapter III for more information onglass fiber preforms.

Surfacing veil is often used in wet or cold molding toprovide a resin-rich layer. Surfacing veil is a nonwovenmat of either glass or polymer adjacent to the partsurface. This improves molded part appearance andcorrosion resistance. Reduced fiber blooming aftersanding is another benefit.

Another factor in glass fiber reinforcement selection isthe type and amount of sizing. Sizing is applied duringglass fiber manufacture and holds the individual glassfilaments together to form glass fiber strands. Glass fiberused in compression molding generally has 1 to 3percent sizing by weight. Sizings can influence fibercharacteristics such as choppability, abrasion resistanceand resin wetout. Sizings are categorized by theirsolubility. Sizings that have low solubility are categorizedas hard. Fibers with hard sizings have good strandintegrity, are easy to chop, and have good strengths.However, fibers with hard sizings can be difficult to wetout during compounding, and can result in fiber print andnon-uniform pigmentation in molded parts. Sizings thatare highly soluble are categorized as soft. Fibers withsoft sizings can be difficult to handle and chop; however,they are easy to wet out during compounding andcontribute to good surface profile and uniformpigmentation in molded parts. Fibers with mediumsizings have characteristics in between fibers with hardand soft sizings.



Page 3 of 7


10. SPECIALTY ADDITIVES—Other additives used incompression molding compounds include:

SMC

Formulatio

n

Component

Typical Materials Quantity

Resin Unsaturated polyester 55-100 parts

Shrinkage

control additive

Low shrink additive:

Polystyrene

Polymethyl

methacrylate

Rubber elastomer

Low profile additive:

Polyvinyl acetate

Saturated polyester

0-45 parts

Catalyst t-Butyl perbenzoate 1-2 parts

Inhibitor para-Benzoquinone

(PBQ)

0.005-0.05 parts

Pigment Various As required

Mold release Zinc stearate 3-6 parts

Filler Alumina trihydrate

Calcium carbonate

150-250 parts

Thickener Group II

Alkaline earth oxides

Hydroxides--MgO,

CA(OH)2

0.5-1.5 parts

Glass fiber Continuous roving

chopped during

compound production,

½ to 2-inch lengths,

commonly I-inch

lengths. Continuous

glass fiber can be used

for structural

applications.

15-65%

• Surfactants to reduce the viscosity of filledsystems allowing more filler to be used.

• Additives to improve flame retardancy suchas antimony trioxides, tris phosphates,chlorinated paraffins and zinc borates.

• Additives to improve weathering such asultraviolet (UV) absorbers.

• Additives to improve compatibility betweenresins and shrinkage control additives

11. TYPICAL COMPOUND FORMULATIONS—Typicalformulations for SMC, BMC, wet molding and coldmolding compound are shown in the tables on this page:

BMC

Formulation

Component

Typical

Materials

Quantity


Shrinkage control

additive


Polystyrene

Polymethyl

methacrylate

Rubber elastomer

Finely powdered

polyethylene


Polyvinyl acetate

Saturated polyester

0-45 parts

Catalyst t-Butyl peroctoate

(injection or transfer)

t-Butyl perbenzoate

(manual)

1-2 parts

1-2 parts

Inhibitor Para-Benzoquinone

(PBQ)

0.005-0.05 parts


Mold release Calcium stearate 7-12 parts


Calcium carbonate

200-400 parts

Glass fiber Chopped roving 1/8 to

1-inch lengths

10-30%



Page 4 of 7


Wet Molding

Formulation

Component

Typical

Materials

Quantity


Shrinkage control

additive


Polystyrene

Polymethyl

methacrylate

Rubber elastomer


Polyvinyl acetate

Saturated polyester

0-45 parts

Catalyst Various Various

Inhibitor Various Various


Mold release Fatty acid or stearate Various


Calcium carbonate

< 100 parts



Page 5 of 7




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Page 7 of 7

COMPRESSION MOLDING: Compounding Processes and Equipment


Part Six, Chapter IIICopyright 2008

In This Chapter1. Sheet Molding Compound

2. Bulk Molding Compound

3. Wet Molding Compound

1. SHEET MOLDING COMPOUND—The sheetmolding compound process involves three basic steps.First, a compound paste is mixed that includes all theformulation ingredients except for the reinforcement.Second, the compound paste and reinforcement arecombined and formed into a sheet. Third, the compoundis allowed to thicken or mature.

A. Mixing of Compound Paste—Mixing of thecompound paste can be done by batch, continuouslyor as a combination of batch and continuous mixingcalled batch/continuous mixing. For all paste mixingprocesses, the paste must be well mixed to ensureall components are completely dispersed. Highlyfilled compound pastes will heat during the mixingprocess and the temperature must be monitored. Tocontrol the thickening reaction, the temperature ofthe paste when delivered to the compoundingequipment should be 85 to 90°F (29 to 32ºC) forbatch processes. Higher temperatures can be usedfor continuous processes.

1) Batch Mixing—Batch mixing involves mixingthe compound paste in a mixing vessel suchas a pail, drum, or mixing kettle using a highshear Cowles mixer. All formulationcomponents are added to the mixing vesselmanually. Batch mixing is an economicalmethod adequate for preparing smallamounts of compound paste for shortproduction runs. Batch mixing has somedisadvantages for long production runs,including low material efficiencies, batch-to-batch variations, and labor requirements fordelivering the batch mix to the compoundingequipment.

2) Continuous Mixing—Continuous mixing isbest for long runs. This method involvespumping liquid ingredients and metering dryingredients to a continuous mixer.Continuous mixing results in very consistentcompound due to accurate pumping andmetering of the ingredients. Continuousmixing also results in very little waste.However, the length of setup time makesshort runs of multiple formulationsimpractical.

3) Continuous/Batch Mixing—Continuous/batch mixing is a combination ofthe batch and continuous mixing processesthat uses ‘A’ and ‘B’ component batch tanks.The ‘A’ side generally includes all compoundpaste ingredients ex-cept thickener. The ‘B’side consists of thickener or thickenerpredispersed in a non-thickenable resin mix.The ‘A’ and ‘B’ sides are pumped at apredetermined ratio through a static ordynamic mixer to the compoundingequipment.



Page 1 of 4

COMPRESSION MOLDING: Compounding Processes and EquipmentCopyright 2008

B. Compounding—The compound paste andreinforcement are combined and thecompound formed into a sheet using anSMC machine. SMC machines are sized bythe width of compound that they produce.SMC machine widths vary from two feet tofive feet. The most common width is fourfeet. A schematic of an SMC machine isshown below:

The compound paste is delivered to two reservoirscalled doctor boxes; it is deposited on a carrier filmthat is being pulled through the machine. A meteringblade called a doctor box blade that is set to apredetermined height above the film controls theamount and thickness of the compound pastedeposited on the film. Continuous strand roving ispulled through a glass chopper and the choppedglass fiber is dropped on the compound paste on thelower film. The upper and lower films meet so that a

SHEET MOLDING COMPOUND continued:sandwich is created between the carrier filmsconsisting of two resin layers with chopped glass inthe center. The carrier films are pulled through acompaction section in which pressure is applied toaccomplish glass wet out. After compaction, thematerial is either wound on a take-up roll orfestooned (folded similar to computer paper) into abox and moved to a thickening or maturation room.

The glass content of the SMC is determined by theheight of the doctor box metering blades, the speedof the glass chopper, and the speed at which thecarrier films are being pulled through thecompounding machine. Glass content of the SMC isgenerally verified during production by comparingthe areal weight of the compound being producedwith the areal weight of the glass being dropped onthe compound. A gamma-backscatter gauge can beadded on a traversing mechanism that monitorssheet weight and adjusts the chopper speed ordoctor blade height. The carrier film is typically anylon/polyethylene co-extrusion. The nylon preventsmonomer loss through the film and the polyethylenecan be used to heat-seal the compound edges toprevent monomer loss. Film edges can also befolded or taped to prevent monomer loss. Thepressure in the compaction section is an important

process parameter. The compaction pressure needsto be high enough to wet out the glass, yet lowenough to prevent compound from being squeezedout of the film edges.

C. Thickening—The thickening or maturation roomis typically controlled at 90°F (32ºC) to provideconsistent thickening of the SMC compound. Toverify thickening and determine compoundreadiness for molding, a retain of the compoundpaste is taken after thickener addition, but prior toglass addition. This retain is stored with the SMCand monitored for viscosity. A Brookfield HBviscometer with T-bar spindles is typically used forthese viscosity measurements.

2. BULK MOLDING COMPOUND—During themanufacture of bulk molding compound all formulationcomponents are combined in the mixer. One of the mostcommon mixer types is a sigma blade mixer. Liquidcomponents of the formulation are pumped or manuallyadded to the mixer and agitated until dispersed. Drycomponents, except for glass fiber, are added next andmixed until thoroughly wet. The glass fiber is the lastformulation component added and is mixed in untilthoroughly wet. Continued mixing of the compound afterglass wet out can result in unnecessary degradation ofthe reinforcement, which can cause reduced mechanicalproperties of the molded part. BMC is ready to moldwhen it is discharged from the mixer, unless maturationtime is required for chemical thickening.

3. WET MOLDING COMPOUND—Wet moldingcompound is the oldest and simplest compression-molding compound form. Reinforcement is incorporatedduring the molding process rather during compounding.Manufacture of wet molding compound involves mixingof the formulation components using a simple Cowlesmixer.



Page 2 of 4

COMPRESSION MOLDING: Compounding Processes and EquipmentCopyright 2008



Page 3 of 4







Page 4 of 4

COMPRESSION MOLDING: Molding Processes and Equipment


Part Six, Chapter IVCopyright 2008


2. Charging

3. Part Formation

4. Finishing

1. INTRODUCTION—As stated earlier, compressionmolding involves pressing and curing a premanufacturedcompound in a closed mold cavity under pressure andoften heat.

The compression molding process involves four steps.First, the compound is inserted or charged into the mold.Second, the mold closes and the part is formed. Third,the part is allowed to cure. Fourth, the formed-and-curedpart is removed from the mold and finished. One to twooperators per press are generally sufficient even forrapid cycle times. Additional operators may be requiredfor very large parts. Operators can work on chargepreparation for the next part or part finishing of the lastpart during molding.

2. CHARGING—Charging (or placing) of the materialto the mold varies based on compound form.

A. SMC—The charge must be prepared byremoving the carrier film from the sheet and cuttingthe sheet to the desired shape. Cutting can be donemanually or by computer-controlled slitting. Twomajor factors influence the configuration of thecharge:

1) First, the charge must contain enoughmaterial to fill the volume of the closed mold.Since, in most cases, it is impractical tomeasure volume, the amount of chargeadded to the mold is controlled by weight.The standard charge weight for a specificcompound and mold are often determinedexperimentally. Depending on part size andthe areal weight of the SMC, several layersof SMC may be needed to achieve therequired weight.

2) Second, the surface area of the charge mustbe sufficient so that the material has time toflow and fill the mold prior to gelation. As thesurface area of the charge increases, thechance of trapping porosity in the moldedparts also increases. Flow of the material inthe mold helps to remove air fromcompound. Complex parts may require thatseveral separate charges be placedthroughout the mold to ensure complete fill.One drawback to multiple charges is thatknit lines are created when the materialflows and the charges meet. Knit lines areoften low in strength and are susceptible tocracking. The shape and surface area of thecharge are again generally determinedexperimentally for a specific compound andmold combination. The surface area of thecharge is generally referred to as apercentage of the mold surface area or moldcoverage.

After the charge is prepared, it may be loaded into themold manually or with automatic loading equipment.

B. BMC—Three basic methods are used forcharging BMC to the mold:

1) Hand charge placement is similar tocharging of SMC in that the charges arecontrolled by weight. After weighing, thecharge is placed in predetermined areas ofthe mold.

2) Transfer involves the use of a plunger toforce material into the mold.

3) Injection involves use of a screw extruder topush material into the mold. For transfer andinjection molding, pressure applied to themold serves to hold the mold together duringthe compound charging rather than tocompress the material into the mold.

Transfer and injection compound charging processeshave shorter cycle times and require less labor thanhand charging, but also require more capital expense.



Page 1 of 5

COMPRESSION MOLDING: Molding Processes and EquipmentCopyright 2008

BMC continued:For wet molding, a fiber preform is placed in the moldand the compound paste is poured into the mold overthe preform. The pressure applied to the mold duringclosing forces the paste to flow into the preform, wettingthe glass fiber.

3. PART FORMATION—Compression molding is doneusing a matched-die tool. A schematic of a simplecompression molding tool is shown below:

Figure 6/IV.1 - Compression molding tool schematic.

A. The tool consists of a cavity and a plug orplunger. Guide pins maintain the proper relationbetween the tool members. The tool cavity forms theouter surface of the part. The tool plunger forms theinner surface of the part being molded and serves tocompress the compound when the tool is closed.The molding compound is thus confined to the openspace between the plunger and cavity while it cures.Numerous features can be incorporated into themolds to facilitate production.

B. Elevated temperature molding requiresprovision for heating in the mold design. Some

presses are equipped with heating platens thattransfer heat to the molds. In some mold designs,the cavity and plunger are drilled to permit a heatingmedium to circulate for heating. Common heatingmediums are oil or steam. A boiler or hot oil heater isrequired to heat the steam or oil and circulate itbetween the mold and heating unit. Knockout orejector pins are often used to push the molded partaway from the mold.

C. Conventional compression molds are madefrom P20 tool steel and are usually chrome-plated.Alternate tool materials such as aluminum, nickelshell and composite can be used for low-pressurecompression molding. Tools made from thesealternate materials are less expensive than toolsmade from tool steel; however, the production runlife of tools made from these alternate materials aregenerally shorter than for tool steel.

D. Compression molding is done in hydraulic,air, or mechanically operated presses with hydraulicbeing the most common. A photograph of ahydraulic press is shown on this page. The twogeneral types of hydraulic presses are downstrokeand upstroke presses:

1) The downstroke press makes use of anoverhead cylinder to move the top platendownward and apply pressure to the mold.This type of press is advantageous formolding large parts since the lower platenremains at a constant level and allows theoperator to walk around the mold and on theplaten as is sometimes required for chargingor demolding large parts.

2) An upstroke press has the cylinderpositioned below, and the ram moves thelower platen upward. This type of pressprovides greater safety for the operator. Amalfunction in the hydraulic circuit causesthe lower platen to drift downward, openingthe press. A hydraulic malfunction in adownstroke press could cause an operatorto be trapped. The hydraulic press shown inthe photograph in Figure 6/IV.2 is adownstroke press.

E. Molds are generally bolted to press platenswith clamp bolts at the front and back. Sheets of



Page 2 of 5


phenolic or glass-bonded mica are often used toinsulate the mold from the press platen. Use ofinsulation reduces the heat transferred from themold to the press and gives better thermal uniformitywithin the mold.

F. Mold daylight is the measurement between theupper and lower platens of the press in the openposition. This dimension minus the stroke (themaximum platen movement) is the minimum dieheight to ensure that pressure will be applied to thepart. The opening between mold halves must besufficient to allow charging and part removal.

G. Press controls generally include pressurecontrols, closing and opening speed controls and aclamp timer. When the clamp time expires, the pressautomatically opens. Safety features, such as lasersystems that prevent the press from closing if anoperator is too close to the press, can also beincorporated.

H. Molding conditions vary between the differentcompound forms. Typical molding conditions areshown in the table below:

Compound

Forms

Pressure Temperature Time

SMC

Conventional

Low

Pressure/Low

Temperature

500-3000

psi

50-500 psi

270-320°F (132-

160ºC)

180-220°F (82-

104ºC)

30

seconds

to 5

minutes

BMC

Conventional

Low

Pressure/Low

Temperature

500-3000

psi

50-500 psi

270-320°F (132-

160ºC)

180-220°F (82-

104ºC)

30

seconds

to 5

minutes

Wet Molding

Compound

<50 psi Room

temperature to

350°F (177ºC)

2 to 10

minutes

I. Molding pressure is influenced by compoundflow characteristics, press tonnage and partcomplexity. On a particular tonnage press, the larger

the part the lower the pressure that can be exerted.More complex parts require high molding pressuresto ensure complete fill. Molding temperature andtime are influenced by compound flow and curecharacteristics and by part size and thickness.

4. FINISHING—Finishing of the part involves flashremoval, drilling of any holes required for assembly, andpackaging. Flash removal can be accomplished withsandpaper, a file or a box knife.



Page 3 of 5




Page 4 of 5







Page 5 of 5

COMPRESSION MOLDING: Troubleshooting Guide


Part Six, Chapter VCopyright 2008

In This Chapter1. SMC Compounding

2. BMC Compounding

3. Molding

1. SMC COMPOUNDING

Problem Potential Causes Suggested Remedies

Glass content too low ................................... Doctor box blade too high .....................

Film speed too fast ................................

Glass chopper speed too slow ..............

Not enough glass rovings ......................

Reduce doctor box blade gap.

Reduce film speed.

Increase glass chopper speed.

Ensure proper amounts are feeding the chopper.

Glass content too high .................................. Doctor box blade too low .......................

Film speed too slow ..............................

Glass chopper speed too fast ................

Increase doctor box blade gap.

Increase film speed.

Decrease glass chopper speed.

Dry fibers in SMC ......................................... Low compaction pressure .....................

Paste viscosity too high .........................

Increase compaction pressure.

Reduce paste viscosity or slow thickening rate.

Compound squeezing out edges of film ........ Compaction pressures too high .............

Paste viscosity too low ..........................

Reduce compaction pressure.

Increase paste viscosity or increase thickening rate.

Compound contains air after compaction ...... Compaction pressures too low ..............

Paste viscosity too low ..........................

Glass content too high ..........................

Increase compaction pressure.

Increase paste viscosity or increase thickening rate.

Reduce glass content.

Shelf life stability ........................................... Premature gelation ................................ Minimize pigment amounts with carbon black, iron

(brown), and cobalt (blue).

Use shelf life inhibitor.

Do not expose the material to excessive heat (store in a

cool room at 60 to 70°F)



Page 1 of 7

COMPRESSION MOLDING: Troubleshooting GuideCopyright 2008

2. BMC COMPOUNDING


Dry filler or glass (can result in mold abrasion,

blisters, etc.) ................................................ Compound viscosity too high .................

Mixing times too short ...........................

Modify compound formulation to lower the viscosity.

Increase mixing times.

Compound too wet (can make compound

difficult to charge and can result in blisters,

porosity, etc.) ...............................................

Compound viscosity too low ..................

Mixing times too long ............................

Modify compound formulation to increase the viscosity.

Decrease mixing times.

3. MOLDING


Non-fills (mold not filled

com-pletely during

pressing) ...........................

Charge weight too low Compound gels before mold is filled

SMC charge area too small .....................

Tool shift deflection .................................

Material discharged from mold ................

Trapped air .............................................

Molding on stops and cocked die/platen .

Increase charge weight.

Decrease molding temperature; decrease mold closing time; increase

molding pressure; decrease compound reactivity.

Increase SMC charge area.

Move charge toward non-fill area.

Decrease pressure; reduce clearance of mold-shear edges.

Remove trapped air from charge prior to compression; decrease area of

SMC charge to increase flow.

Increase charge weight after confirming gap is 0.003 inch to 0.010 inch

around all sides of the mold.

Blisters .............................. Trapped air .............................................

Trapped or unreacted monomer ..............

Dry glass in compound ...........................

Weakness at knit line ..............................

Incomplete curing ...................................

Contaminants such as moisture, press

oils, lubricants, and external mold release

...............................................................

Remove trapped air from charge prior to compression; decrease area of

SMC charge to increase flow. Slowing press closing speeds will reduce

initial flow and the tendency to trap air in the laminate. Tool misalignment

during closing can cause uneven flow.

Reduce mold temperature; decrease compound reactivity; reduce

styrene content of compound.

Increase SMC roller compaction; increase mixing time for BMC.

Modify charge to prevent formation of knit line.

Increase cure time; increase mold temperature; increase compound

reactivity.

Check mold, SMC, and raw materials for contaminants.



Page 2 of 7

MOLDING (continued)


Cracks .............................. Excessive shrinkage ...............................

Weakness at knit line ..............................

Sticking to mold surface ..........................

Sticking to flash area ..............................

Insufficient shrinkage ..............................

Sever undercuts or ejector pins holding part

down, causing fracture ............................

Unbalanced ejector pins/plate .................

Ejector speed is too fast ..........................

Modify compound formulation to provide better shrinkage

control.

Modify charge to prevent formation of knit line.

Modify mold release in compound; apply external mold release

to mold.

Clean and wax flash area.

Modify compound to increase shrinkage.

Remove problem undercut.

Verify ejector pin motion.

Reduce ejection speed.

Surface porosity ................ Area of charge is too large; air cannot escape

because of short flow path .......................

Pre-gel ....................................................

Unwet glass or air in compound ..............

Low viscosity compound .........................

Contaminants such as moisture, press oils,

lubricants, and external mold release ......

Air entrapment due to dirty shear edges and

vacuum ports ..........................................

Mold halves too close in temperature,

entrapping air ..........................................

Decrease charge area.

Decrease mold temperature; increase closing speed; decrease

compound activity.

Increase SMC compaction pressure; increase BMC mixing

times.

Increase SMC maturation viscosity; increase filler or glass

content.

Check mold, SMC, and raw materials for contaminants.

Clean shears or vent ejector pins.

Maintain temperature differential to keep shears edge open to

allow air to escape.

Warpage or distortion of molded

part ........................................... Shrinkage after demolding .............................

Incomplete cure .............................................

One mold surface much hotter than the other

Unbalanced construction ................................

Fiber orientation .............................................

Cool parts in jigs having desired shape; modify compound to

improve shrinkage control.

Increase cure time; increase mold temperature; increase

compound reactivity.

Reduce differential between mold surfaces.

Change laminate design.

Shorten flow path by modifying charge; increase compound

viscosity to improve fiber carry.

Wavy surface on flanges or ribs . Interruption of uniform flow ............................. Increase pressure; change mold design; modify charge.

Wavy surface on main part

surface

Insufficient shrinkage control .......................... Reformulate compound to improve shrinkage control.



Page 3 of 7


MOLDING (continued)


Sink marks at rib or flange

locations ...................................

Non-uniform shrinkage during molding ...........

Charge laid directly over ribs or bosses

causes shrinkage ...........................................

Low temperature differential causes

simultaneous curing on core and cavity,

increasing shrinkage .......................................

High molding pressure throughout hold time ..

Reformulate compound to improve shrinkage control; increase

mold temperature on one half of mold; shorten chopped fiber

lengths; change mold design; modify charge.

Optimize charge pattern.

Increase temperature differential by 20°F (11ºC) with

appearance surface at a higher temperature.

Thirty seconds after compression reduce pressure by at least

25 percent.

Scumming (dull or streaked

areas on the part that transfer to

the tool surface) ........................ Failure of the internal mold release at molding

temperature ...................................................

Incompatiblity of resin additives ......................

Molding temperature below that of release agent; increase tool

temperature. Increasing flow distance has a cleaning effect on

the tool.

Incompatibility or amount of shrinkage control additive;

reformulate material. Pre-gel of material cause separation of

shrink control additives; increase the gel time of material.

Laking (areas of low gloss on

cooled part) ............................... Pre-gel ...........................................................

Insufficient molding pressure ..........................

Mold contamination ........................................

Too much shrinkage ......................................

Mold temperature is low, or there are hot and

cold spots on tool ...........................................

Decrease mold temperature; increase closing speed; decrease


Increase molding pressure.

Clean and condition mold.

Modify formulation to reduce shrinkage.

Adjust tool temperature and heating issues; increase

temperature on tool surface.

Dull part surface ........................ Pressure too low ............................................

Incomplete cure .............................................

Dull mold surface ...........................................

Increase pressure.

Increase mold temperature; increase cure time; increase


Rework mold surface to a higher polish.

Flow lines (local waviness on

part surface) .............................. Long flow path creating fiber orientation .........

Low viscosity creating fiber orientation ...........

Modify charge pattern.

Increase viscosity of compound to improve fiber carry.

Dieseling or Burning (dark brown

surface stain, generally in

nonfilled area) ...........................

Trapped air and styrene vapors raise

temperature to ignition point ........................... Modify charge so material pushes air out of mold as it flows;

reduce closing speed. Check for hot or cold spots on the mold

surface.



Page 4 of 7

MOLDING (continued)


Cobwebbing (white threadlike

strands that appear on the SMC

during carrier film removal) ........ Polyester/Thermoplastic resin incompatibility . Insufficient 1st hour thickening; increase level to obtain 500,000

cps in the paste. Excessive amount of thermoplastic additive;

reduce level. Investigate one of the many additives that

increase thermoplastic compatibility.



Page 5 of 7




Page 6 of 7







Page 7 of 7

CASTING: Introduction


Part Seven, Chapter ICopyright 2008

In Part Seven:

Chapter I: Introduction

Chapter II: Cast Polymer

Chapter III: Solid Surface

Chapter IV: Flexible Casting Resins

Chapter V: Thermal Shock Testing Request

Casting is the simplest manufacturing process for

unsaturated polyester resin. Casting processes are

varied, but all involve pouring catalyzed resin, either

filled or unfilled, into a mold and allowing it to harden or

cure. Once cured, the part retains the shape of the mold.

It is then removed or demolded and ‘finished,’ meaning

the surface can be sanded, polished, and/or painted.

Casting applications include but are not limited to

decorative figurines, polymer concrete, flex trim

moldings, furniture, embedment castings (e.g.,

paperweights), and countertops and bathware. Although

the general casting process is the same for all

applications, raw materials used vary depending on the

performance requirements for each type of finished

product.

Three main categories of the casting industry will be

covered in this text. These are cast polymer, solid

surface, and flexible casting resins.



Page 1 of 2







Page 2 of 2

CASTING: Cast Polymer

Composites

Applications Guide

Part Seven, Chapter IICopyright 2008

In This Chapter:1. Introduction

2. Materials

3. Molds

4. Manufacturing Process

5. Trouble Shooting Guide

6. Supplies for Marble Production

1. INTRODUCTION—This section will focus on thecountertop and bathware industry, most commonlyreferred to as Cast Polymers. Cast polymer products areused in commercial, residential, industrial, and medicalareas. The cast polymer product line has extendedbeyond the original kitchen and bath markets. Examplesof cast polymer products are vanity tops, sinks, bathtubs,shower pans, wall panels, countertops, windowsills,flooring, bar sinks, interior and exterior facades,banisters, and furniture, with the list continuing to grow.There are three distinct product lines within castpolymers:

• Cultured Marble—gel-coated surface, filled withcalcium carbonate, usually pigmented and/orveined, opaque in appearance.

• Cultured Onyx—gel-coated surface, filled withaluminum trihydrate, usually veined with anonpigmented background, and translucent inappearance, showing depth like natural onyx.

• Cultured Granite—gel-coated surface, filled withspecially designed granite filler to produce amulti-colored speckled appearance.

An unlimited variety of colors, cosmetic designs, andshapes that can be manufactured or fabricated providecast polymer products with distinct advantages over theirnatural counterparts. In addition, natural products areporous (which can become a source of bacterial growth)and can easily be stained, while cast polymer productsare not porous and are stain resistant.

2. MATERIALSA. Gel Coat—For cast polymer products ofcultured marble, onyx, and granite, the use of gelcoat is required. Gel coat is not used with solidsurface products. It is a polyester coating that isapplied to the mold surface and becomes an integralpart of the finished product. The function of gel coatis to protect the part from its environment, providingchemical resistance, water resistance, andweathering resistance (UV stability). The gel coat isalso accountable for the part’s cosmetic surface anddurability. It is the gel-coated surface that is visibleand therefore a critical aspect of the part.

Both pigmented and clear gel coats can be used toproduce cast polymer products although clear gelcoats are generally more popular.

Pigmented gel coats are mainly used to producecultured marble. Parts produced with pigmented gelcoats are solid colored. The pigmented gel coatforms an opaque coating and hides the color of thematrix poured behind it. Pigmented gel coats used incultured marble are formulated similarly to thoseused in open molding.

Clear gel coats add depth and dimension to the partand allows artistic colors and designs in the matrix tobe viewable. In cultured marble, clear gel coatprovides the ability to view vein patterns in thematrix. Clear gel coat is required with onyx toaccentuate the translucency and depth of theveining to more closely resemble natural onyx. Cleargel coat is also required to show off the multi-coloredeffect of granite filler.

Cultured granite can be manufactured using one oftwo methods:

1) Granite-effect filler is mixed into the resinand poured behind a clear gel coat.

2) Specially designed spray granite chips aremixed with a specially designed clear gelcoat and then sprayed onto the mold.Standard marble matrix is poured behind it.



Page 1 of 24

CASTING: Cast PolymerCopyright 2008

MATERIALS/ Gel Coat continued:

Clear gel coats used in the cast polymer industry arespecifically formulated for cast polymer applications.Key differences from clear gel coats formulated forother industries are lower color and slower curerates. Clear gel coats to be used with spray granitechips also have different viscosity and spraycharacteristics.

To meet performance requirements of bathwareproducts both pigmented and clear gel coats mustbe based on ISO/NPG polyester resins. Please referto Part Four, Open Molding for additional informationon gel coats.

B. Resin—Casting resin is mixed with fillers tomake the matrix. The matrix gives the cast part itsstructural integrity. Resin suppliers formulate castingresins from several components, including thepolymer, reactive monomer, promoters, inhibitors,and specialty additives. The specific componentsand amounts used are dictated by the end-useapplication, manufacturing process, required curebehavior, end-use physical properties requirements,and manufacturing plant conditions. Plant conditionscan dictate that resin gel time and/or viscosity bevaried to account for seasonal temperature changes.

Unsaturated polyester polymers are the basis ofcasting resins. Cultured marble, onyx, and graniteresins are based on orthophthalic polyesters.Cultured marble resins can also be based on hybridpolyesters. Because of color constraints, hybridpolyesters are generally not acceptable for culturedonyx or granite. (For additional information on resinchemistry see Part Three, Chapter II.)

There are several advantages to using hybridmarble resins versus orthophthalic marble resins :

1) Hybrid resins are inherently lower inviscosity and higher in solids content.This is an advantage when reportingemissions (HAP and VOC content) forpermit requirements.

2) Hybrid resins have superior filler wettingcapabilities which allow higher filler loading.This helps to reduce material cost byreducing resin percentage in the matrix.

3) Hybrid resins tend to develop green strengthand cure faster.

4) Hybrid resins have lower peak exotherm andshrinkage rate.The low shrinkage rate reduces the build-upof internal stress during the cure of the part,which improves the part’s thermal shockresistance. Also, because of the lowexotherm and shrinkage, hybrid resins areideal for making large parts such as tubsand shower pans.

5) Hybrid resins are very compatible withlightweight fillers.

The monomer fulfills two roles in the polyester resin.First, it reacts and cross-links with the unsaturationsites in the polymer to form the cross-linkedthermoset material. Second, it reduces the viscosityof the polymer to workable levels. The most commonmonomer used in casting resins is styrene.

Promoters, also called accelerators, split theperoxide catalysts used to cure casting resins intofree radicals. These free radicals attack theunsaturation sites in the polymer, preparing them forreaction with the monomer. Promoters used incasting resins determine the cure behavior and alsohave a significant impact on the color of the finishedpart. In general, the higher the promotion level thedarker the cured resin color. As a result, the typesand amounts of promoters used in casting resinsvary depending on the production speed and colorrequirements for each application.

• For cultured marble, the matrix is usuallypigmented or poured behind pigmented gelcoat, making the cured resin color lessimportant than for some other applications.As a result, marble resins are typically highlypromoted for faster cure.

• For cultured onyx and granite, clarity andlow-cured casting color are critical factors.Cultured onyx cannot be pigmented asheavily as cultured marble because it willreduce its translucency. As a result, onyxand granite resins have very low promoterlevels and correspondingly slower curerates.

• Swing or dual-purpose resins are acompromise between marble and



Page 2 of 24


MATERIALS/Resin continued:

onyx/granite resins. Swing resins contain ahigher level of promoters than onyx/granitebut less than marble. The result is lowercured casting color than cultured marble butfaster cure rates than onyx/granite. For mostmanufacturers, the small sacrifice in curedcolor is worth the increased speed ofproduction with onyx and granite products.In many cases, the color difference is notnoticed. The slower cure of swing resins incultured marble applications can beaddressed with catalyst. Manufacturers thatdo not want to buy separate resins formarble and onyx/granite applications alsouse swing resins.

Inhibitors provide shelf life stability to casting resinsas well as help control the working time or gel time.Free radicals generated in the polyester resin duringstorage or after addition of peroxide catalyst reactpreferentially with the inhibitors. Only after all theinhibitors are consumed does the cross-linking orcuring process begin.

In addition to the above materials, a number of otheradditives can be used in casting resin formulationsto affect properties. These include processing aidssuch as air release agents and wetting agents.Additives can also be used to affect the product’sperformance, such as UV absorbers and lightstabilizers for weathering performance.

C. Fillers—The filler is the largest part of the castpolymer composition. The type of filler to be useddepends on the cast polymer product.

1) Cultured Marble

a) Calcium Carbonate (CaCO3)—Typicalmarble filler is calcium carbonate(ground limestone). CaCO3 is minedand ground into small particles. Its sizeis measured in units called mesh. Fillerparticles are sorted through screenswith different size openings. Mesh sizeis designated by the number of holesper linear inch, with lower numbersindicating a coarse or large particle sizeand higher numbers indicating a fine orsmall particle size. CaCO3 fillers are

supplied as ‘all coarse’ or ‘all fine’particles or as preblended bags ofcoarse and fine particles.

A mixture of particle sizes of filler isused to provide maximum loading, withcoarse at 40 to 200 mesh and fine at325 mesh. Fine particles fill in betweencoarse particles so that resin-rich areasare reduced and higher filler loadingscan be achieved. For temperaturesbelow 85°F, a mix ratio of 2 parts coarseto 1 part fine provides excellent loadingproperties while avoiding warpage andcracking problems. For temperaturesabove 85°F, a mix ratio of 3 partscoarse to 2 parts fine will maintain thesame matrix viscosity.

b) Dolomite—Just like CaCO3, dolomite isa mined mineral, a mixture of calciumcarbonate and magnesium carbonate. Itis supplied just like CaCO3. Dolomite ismore abrasive than CaCO3 andtherefore may require more equipmentmaintenance.

c) Lightweight Fillers—The use oflightweight fillers in cast polymerproducts has been steadily increasing.Lightweight fillers are hollow spheresmade of glass (silica) or plastic. Theyoccupy space or volume but do not addweight, which effectively reduces theweight of a given part without changingits dimensions. Lightweight fillers areused with CaCO3. They can be boughtseparately or preblended with CaCO3 toa known weight displacement. Typically,these fillers demand a higher resinpercentage for wet out and to maintain aflowable viscosity. Also, because of itsinsulating effect, lightweight fillers causethe exotherm of the curing part toincrease.



Page 3 of 24


2) Cultured Onyx

a) Aluminum Trihydrate (ATH)—The fillerof choice for cultured onyx, ATH is a by-product resulting from the processing ofbauxite minerals in the manufacturing ofaluminum. Onyx grade ATH is muchbrighter white than CaCO3, thuseliminating the necessity of usingbackground pigment. It is a semi-translucent granular filler which providesa visual effect like natural onyx and hasthe added feature of acting as a flameretardant. At temperatures of 410°F(210ºC), ATH releases its waterparticles, slowing combustion andreducing smoke generation.

b) Lightweight Fillers—The use oflightweight fillers is not recommended incultured onyx since this would reducetranslucency.

3) Cultured Granite—Granite effect fillers aregaining in popularity. Filler suppliers havespecially formulated colors and particle sizedistributions to achieve a multi-coloredspeckled granite appearance and to give theproduct a cosmetic textured look. Thecolored granules may be coarse groundminerals or synthetically made frompigmented resins. The resin demand willvary greatly depending on the granulesize(s) and distribution. There is a differencein granite-effect filler mixed into the matrixversus spray granite filler mixed into the gelcoat and sprayed; therefore, method ofapplication needs to be noted whenpurchasing these fillers.

While inexpensive initially, if not chosen andchecked properly, fillers can become extremelycostly. For example, if too much coarse filler is usedand subsequently settles, a resin-rich area will resulton the back side which could cause warpage. If toomuch fine filler is used, the viscosity will be veryhigh, resulting in air entrapment. If the fillers containtoo much moisture or become damp, they will affectthe gel and cure.

Lot-to-lot variations and contamination of fillers can

also affect the cured casting color. There can besignificant particle size variations from lot-to-lot asshown in the analysis in the first chart on thefollowing page.

Each lot should be checked as soon as it isdelivered to determine if these factors will affect gel,cure, color, and matrix viscosity. To make thisdetermination, make a part with the new filler andcompare it to parts made with the lot already in use.Do not wait until time to switch to a new lot. Fillersshould be checked in conjunction with the resin fortheir effect on matrix color, gel time, viscosity, andcure properties.

D. Catalyst/Initiator—Catalyst is the componentneeded to ‘harden’ the polyester resin mix into asolid mass. Technically, catalyst causes the reactionbut does not participate in the reaction. In thecomposites industry, the correct term is initiator,which starts the reaction and is consumed by thereaction. There are three common types of roomtemperature initiators used in cast polymers:

1) Methyl Ethyl Ketone Peroxide (MEKP)—Themost widely used initiator, MEKP is a clearliquid that easily mixes into the resin. It is themost cost-effective choice and is available indifferent strengths to give a variety of curingcharacteristics. Recommended range is 0.5percent to 3 percent catalyst level based onresin amount.

2) 2,4-Pentadione Peroxide (2,4-PDO)—Alsoknown as acetylacetone peroxide (AAP),this initiator offers fast cure time and highpeak exotherm. Although it does lengthengel time, Barcol hardness builds quickly.Typically, 2,4-PDO is used during the coldertemperatures. It is available separately orpreblended with MEKP; however, preblendsare the most popular. When blended, theMEKP controls the rate of the gel time andthe 2,4-PDO provides the faster cure rateand higher peak exotherm. Recommendedrange is 1 percent to 2 percent catalyst levelbased on resin amount. Above 2 percent,2,4-PDO peroxide may inhibit cure. The onlydisadvantage with this initiator is that withsome resins, cured casting color may have ayellowish tint.



Page 4 of 24


Catalyst/Initiator continued:

Sieve Size Lot A% Lot B% Lot C

%

40 1.5 1.75 1.5

60 7 6.5 6.5

80 6.5 6.7 7.5

100 7 10 10.5

120 7 7.25 4

150 6 12 6

200 19.5 19.75 30.5

Through

200

45.5 36.75 33.5

3) Cumene Hydroperoxide (CHP)—CHPlowers peak exotherm and lengthens geland cure times. Lower peak exothermreduces cracking, crazing, and shrinkagebut also slows down Barcol development.CHP is most popularly used during hottertemperatures and/or on thick parts likeshower pans and tubs. It is availableseparately or pre-blended with MEKP;however, preblends are the most popular.

Some control over gel and cure rates can be achievedby changing initiator levels and blending the abovementioned initiators. Initiator level should be maintainedbetween 0.5 percent and 3 percent with 1.25 percentbeing the norm. Initiator levels below 0.5 percent maycause curing problems. Levels of 0.5 percent shouldonly be used during hot ambient temperatures where theheat will serve as a secondary catalyst or in large massproducts (e.g., tubs) where higher exotherms will begenerated because of the part’s thickness. Initiator levelsabove 3 percent are at the point of diminishing return,

with very little improvement seen in relation to the use ofthe higher amount. If the initiator level is excessive, theinitiator will cancel itself out to the extent that thereaction will stall. As the initiator level moves outside therange of 0.5 percent to 3 percent, change should bemade to a cooler or hotter initiator strength. Once thischoice has been exhausted, a different gel time versionof the resin should be ordered from the resin supplier.

3. MOLDS—The mold determines the shape, texture,and gloss of the finished part. It is a mirror image of thepart, so any defect in the mold will be reflected in all thecastings made from that mold. Simple molds have onesize and shape. Custom parts require specialdimensions so dividers and moveable bowls provide theflexibility to cast these one-time needs. Holding them inplace can be done with double-face tape, suction cups,clamps, hot glue, or other ingenious methods. Providingcosmetic transitions, such as a small radius where thefloating bowl or divider bars meet the deck, can beaccomplished using wax fillets or clay.

NOTE: Different clays vary in formulation, and withsome, there may be technical problems that can showup as fisheyes, pre-release, or that simply cause cureproblems with the gel coat. One way to reduce theseproblems is to dust the applied clay with baking soda orfumed silica. Then make sure to blow off the excesspowder before applying the gel coat.

A. Mold Materials—A number of materials can beused to make a mold. The most common are shownin the table below.

B. Mold Configuration— Vanity top molds aremodular or custom. Modular molds are fixed-size,one-piece, seamless construction with bowls, backsplash, and any special features built in. Custommolds may have built-in back splash but bowls anddividers are separate parts and positioned asdesired.

Vanity top molds include the following accessories:

1) Drain Plug—Usually made of polyethylene,the drain plug measures 1.75 inches indiameter. It can be permanent or removable.It serves to form the drain hole andattachment point for an overflow assembly(if used). The plug is attached to the bowlduring set up before gel coat application.



Page 5 of 24


2) Overflow Assembly—Although not requiredby the national plumbing codes, overflowsmay be needed for some specificapplications. A permanent plastic draincollar and tube may be encapsulated andremain in the bowl or a reusable flexibletube may be retrieved from the cured part.The tube attaches to the bowl and drain plugand should be installed after gel coat isapplied. The end connected to the drain plugshould remain unattached until after gelcoating for easier gel coat application to thebowl. This will allow the critical area of waterimpingement to be easily gel coated to theproper thickness. The overflow tube shouldbe spaced at least 1/2 inch from the bowlsurface to help prevent cracking.

Mold Type Advantage Comments

Fiberglass Easy to make

Long lasting

Can be textured

Radii can be built

in

Easy to repair

Easy to handle

Easily customized

Type most often used

Stainless

Steel or

Chromed

Steel

Durable

Hard surface

Smooth finish

Expensive

Deep scratches and

dents not easily

removed

Formica or

Melamine

Easy to make

Can be textured

Inexpensive

Not long-lasting

Not durable

Surface finish is fair

Glass Perfectly flat

Low maintenance

For flat panels only

Care must be taken

not to crack or scratch

the surface

3) Faucet Plugs—These form one-inchdiameter holes for faucet installation. Plugsmay be solid knockouts (re-usable) orcardboard rings that remain in the part.Plugs may be placed on wet gel coat to be

held in position when the gel coat cures.Clay can also be used to hold them inposition.

4) Female Hat—The hat functions to hold thematrix in place to form the bowl’s wallthickness. It is contoured to the male bowlmold and allows for overflow assembly (ifused). It is usually constructed withfiberglass, polyethylene, or polystyrene.Fiberglass and polyethylene hats arereusable (removed from part). Polystyrenehats are permanent (remain on the part).Hats may be full or partial. Full hats areusually used with modular molds. Full hatscompletely cover the mold and can beclamped in place for the one-pourproduction method. Partial hats aresometimes used with modular molds andalways on custom molds since these moldswill differ in bowl location. Partial hats coverthe bowl only and are used in the two-pourproduction method.

C. Polyethylene Dividers—These are often usedto custom-size flat areas, such as wall panels, backsplash, and vanity decks, into various shapes orsizes.

4. MANUFACTURING PROCESS

A. Overview—The 12 steps listed in the followingtable provide a very general outline of themanufacturing procedure for cast polymer:



Page 6 of 24


Overview continued:

Step # Action

1.Prep and set up molds.

2.Apply mold release agent to the molds.

3.Spray gel coat onto the mold.

4.Remove gel coat overspray from mold flange while

gel coat is still wet. This is easily done by applying

masking tape on the flange before gel coating and

then removing the tape after gel coating.

5.When the gel coat is ‘castable,’ apply matrix (resin,

filler, catalyst, pigment) to the gel-coated mold.

6.During the process of transferring the matrix into

the mold, a variety of veining techniques can be

applied to achieve the final cosmetic appearance of

the part.

7.Vibration is added to level the matrix in the mold

and remove air bubbles from the gel-coated

surface.

8.Remove excess matrix from the mold flanges after

the matrix gels but before it shrinks.

9.When possible, remove the back hat, open the

back splash, and eliminate any other constraints on

the part.

10.Demold the part as soon as possible to avoid

internal stress fractures.

11.After demolding, place the part on a supporting

surface to retain its shape during cure. If it is a solid

surface product, it is recommended the part be

postcured.

12.Once cured, the part is finished (trimmed, sanded,

and polished) and repaired (if necessary).

B. Mold Preparations and Maintenance—Themold determines the texture, smoothness, and glossof the finished part. It is imperative that the mold bekept in optimum condition. New molds must bebroken in following the directions of theirmanufacturer. (If building a mold, refer to Part Eighton Polyester Tooling for suggestions regardingprocedure.) Molds for marble will last through theproduction of many parts and provide maximumperformance if good mold maintenance is practicedand good workmanship is used in producing themold.

A mold maintenance program is essential in amarble shop to ensure the long life of polyestermolds. While it sometimes suffices to rewax a moldwhen it starts pulling hard, CCP has found thatproblems such as sticking and polystyrene build-upresult from neglect of the mold over time. CCPsuggests a routine mold prep schedule. It is farbetter to prevent polystyrene build-up with a good,consistent preventive maintenance program than toallow molds to get into bad shape.

To determine the prep schedule, start bydetermining how many pulls (parts) it takes for themold to start sticking. Then routinely prep and waxthe mold before this number is reached. Forexample, if the mold starts to pull hard and gloss isdiminished after seven parts are pulled, then alwaysprep and rewax the mold after pulling the sixth part.With careful adherence to such a program, moldswill last longer and produce better-looking parts withless patching.

The mold prep area should be completely enclosedand away from the production area. There should beisolated stalls for grinding and a separate area forgel coating.

Mold build-up should not be confused with what wasonce referred to as ‘wax build-up.’ Wax build-up ismore correctly stated as ‘wax leave-on” because thebuild-up occurs when excess wax is not buffed off.In fact, mold build-up is styrene (polystyrene) thathas come from the production gel coat. It adheres tothe mold mainly for these reasons:



Page 7 of 24


Mold Preparations and Maintenance continued:

• Wax leave-on• Pulling parts too soon (the more ‘green’ a

part when pulled, the more susceptible it isfor styrene to adhere to the mold)

• Too many parts made in the mold withoutproper maintenance

Normal mold preparation involves machine polishingthe mold with a glaze. If the mold is very hazy andhas some polystyrene build-up, a coarser compoundshould be used and followed with the glaze. Themold should be washed and rinsed with cold waterto remove compounding dust and compoundvehicle.

Some compounds can cause sticking if left on themold. Six fresh coats of mold wax should follow thewater wash. The fish eye and prerelease tendencywill always be greater after this fresh wax. However,if the gel coat is sprayed to a thickness of 18 to 20mils, the fish eyes should be covered, andprerelease tendency is minimized.

If the mold has a lot of build-up, it must be removedby scrubbing with a commercial stripper (toluene,methyl ethyl ketone, ethyl acetate, or ‘wax off’). Donot use styrene for cleaning molds. All of thesecommercial strippers are flammable and healthhazardous. Safety precautions should be observed:

• Read the Material Safety Data Sheet(MSDS).

• Wear gloves.• Wear safety glasses.• Make sure the area is well ventilated.• No smoking.

After molds have been stripped, if there is stillroughness on the mold surface, then the moldshould be sanded with sandpaper no coarser than600 grit and polished. If roughness or scum is left onthe mold, it will permit quicker mold/polystyrenebuild-up when put back into production. If using apolymer mold release system, follow supplier’sinstructions. Too much polymer mold release willcause fish eyes in the gel coat.

For more information, please refer to Chapter VIII,Mold Maintenance, in Part Eight on PolyesterTooling.

C. Gel Coat Application—Application of gel coatis the most critical aspect of cast polymer productionsince it provides the ultimate first impression of theproduct. Also, performance of the finished product isdirectly related to how well the gel coat is applied.For information on spray equipment and technique,please refer to Chapter II, Conventional Gel Coat,Section II.4, Application, in Part Four on OpenMolding.

Clear marble gel coats, specifically designed for castpolymer, and pigmented gel coats should be used inproduction of cast polymer. Typically, gel coat issprayed in a wet film thickness of 16 to 24 mils. Forparts that are not as critical (for example, wallpanels), the minimum wet film thickness isacceptable. For parts with high exposure to waterimpingement, the maximum wet film thickness isrecommended. It is important that the gel coat isapplied evenly throughout the part, therefore the useof mil gauges is encouraged.

Film gel time must be long enough to allow levelingand air release but short enough to prevent thestyrene in the gel coat from attacking the releasebarrier between it and the mold surface. If the lattersituation occurs, it would cause release impairmentleading to cracking and edge peeling or stress andshrink lines. Likewise, if the gel coat thickness isinsufficient, the styrene in the marble matrix canpenetrate the gel coat into the mold release andcause similar problems. Thin gel coat also may notcure thoroughly.

The gel coat is allowed to partially cure beforemarble mix is poured. Cure times are normally 30 to90 minutes depending upon plant temperatures,catalyst level, and air movement. Slight airmovement speeds cure by moving styrene vapor offthe gel coat surface. Styrene vapor does inhibit gelcoat cure. Forced air ovens, set at 100°F to 120°F,can reduce the gel coat cure time to a range of 15 to20 minutes. Uneven heat, too much heat, extendedtime, and too little or too much air movement in theoven may cause pre-release.

NOTE: Gel coats are flammable. Ovens used mustbe designed to accommodate flammable materials.



Page 8 of 24


D. General Matrix Formulation—Listed aregeneral starting points for each product line. Asproduction continues, the matrix formulationbecomes customized to each manufacturer.

1) Cultured Marble

Resin

CaCO3

Base

Pigment

Initiator/

Catalyst

22 - 26%

74 - 78%

0.5 - 1.5%

0.5 - 3.0% (based on resin content)

Resin recommendation of 22-26% is baseon orthophthalic polyester resin. If usinghybrid based marble resin,the starting resinrecommendation is 20-24%.

2) Cultured Onyx

Resin

Onyx Grade

ATH

Initiator/Catalyst

26 - 30%

70 - 74%

1.0 - 3.0% (based on

resin content)

Due to finer particle size ATH filler, culturedonyx requires higher resin content thanmarble to wet out and to reduce matrixviscosity to aid in air release. Due to thetranslucency of this product, it is necessaryto release as much air as possible (unlikeopaque cultured marble where it is onlycritical to remove the air from the gel coatsurface). Catalyst level is higher than marbledue to the lower promoter level of onyxresin.

3) Cultured Granite

Granite Matrix (granite mixed into the

matrix)

Resin

Granite Effect

Filler

Initiator/Cataly

st

22 - 30%

70 - 78%

1.0 - 3.0% (based on

resin content)

Resin content varies greatly with graniteeffect fillers depending on the particle size

and distribution of the granite particulates.The larger the granite chips, the lower theresin content. The finer the granite chips, thehigher the resin content. If the mix is tooloose (too high in resin content), the largerparticulates will fall to the gel coat surfaceand not achieve the desired appearance. Ifthe mix is too thick, air bubbles will betrapped in the matrix. Initiator/catalyst levelwill also vary greatly depending on thegranite color(s) being cast. It is advisable tokeep a log of initiator/catalyst level versusgranite color for reference.

Spray Granite (granite mixed into the gel

coat)

Clear Gel Coat

Spray Granite

Effect Filler

Initiator/Catalyst

50 - 60%

40 - 50%

1.5 - 2.0% (based on resin

content)

Unlike granite filler mixed into the resin andpoured behind clear gel coat, spray granite isgranite filler mixed with a specially formulatedclear gel coat and sprayed as the gel coat.Standard marble matrix is poured behind it.There is a difference in appearance betweenthese two methods of processes. As above,there is a wide range of gel coat/resin contentdue to the particle size and distribution of thegranite particulates. Please refer to the previousnotes on Granite Matrix.

It is a common practice to use marble clear gel coatas the carrier for the spray granite. The advantage isin not having to stock another product. Thedisadvantage is that gel coat is designed to cure inthin films and therefore is very reactive. To get thecoverage or ‘hide’ of spray granite, 20 to 30 mils filmthickness is required. Depending on granite particlesize, thicker film thicknesses may be required. If thelayer is too thin, the matrix behind it will showthrough. At 20 to 30 mils film thickness, standard gelcoat may cure too fast and exotherm too high,resulting in a variety of problems such asprerelease, excessive shrinkage, distorted



Page 9 of 24


Cultured Granite continued:

surface, etc. Specially formulated gel coat hasbeen developed to resolve this issue. Theadvantage is that the specially formulated gelcoat is very highly thixed to help suspend thegranite particulates and will cure at a muchlower exotherm than standard clear gel coats.The disadvantage is in having to stock anothermaterial.

The typical application process for spray graniteis to:

• Apply 10 to 12 mils of wet clear gel coatto the mold (this will give the finishedproduct a smooth glossy surface andadd depth to the finish appearance).

• Wait for the gel coat layer to dry to atacky finish, then spray on 25 to 35 milsof the wet spray granite mix (gel coat orresin plus spray granite effect filler).

• Wait for the spray granite layer to dry toa tacky finish, and then pour on themarble matrix (it is recommended topigment the background of the marblematrix the same general color as thespray granite for cosmetic purposes).

There are differences between granite effect fillersintended to be mixed into the matrix versus spraygranite intended to be mixed into gel coat. Makesure to specify to the supplier which product isneeded.

E. Matrix Mixing Methods—There are severaldifferent methods for mixing the matrix (incorporatingthe resin, pigment, catalyst, and fillers). If possible,add and mix the catalyst to the resin first beforeadding the filler. Mixing in the catalyst first willensure even distribution of the catalyst throughoutthe mix. Also, if adding separate fine and coarsefillers, mix in the fine or lightweight fillers first sincethey are more difficult to wet out before the coarsefillers. When using dry pigment, make sure thepigment is well-mixed into the resin before addingcatalyst. If dry pigment comes into direct contact withcatalyst, it creates a gaseous reaction that will leavemany air voids in the matrix.

1) Hand Batching/Small Batching Method—Materials are manually measured and mixedin a batch mixer, making 100 to 400 poundsof matrix per batch.

a) Premeasure all ingredients first.b) Add measured resin into mixing pot.c) If adding background color, add pigment

to the resin. Mix for one minute. Add asmall amount of filler to help dispersethe pigment.

d) Add catalyst to the pigmented resin. Mixfor one minute.

e) If using lightweight filler, add to themixing pot and mix until all is wet out.

f) If using separate fine and coarse fillers,add fine fillers first. Mix until all is wetout. Then add coarse filler and mix untilall is wet out.

g) Scrape down sides and mixing blade forunmixed material.

h) Mix for additional three minutes toensure thorough mixing.

i) Add veining pigment(s) if desired.j) Pour onto molds.

2) Auto-Dispensing Method—Auto-dispensingequipment is designed to deliver measuredamounts of resin and filler into the mixingpot. The primary advantage is that mostauto-dispensing units have resin heatingcapability that allows higher filler loading.This equipment eliminates the labor andtime previously required for measuringmaterials, delivers consistent materialquantities, and reduces material costs byheating up the resin to increase fillerloading. Maintenance is critical. As for anymachine, calibration should be performedregularly to ensure proper delivery ofmaterial amounts.

a) Operator chooses preset formulationand enters batch size into the machine.

b) Heated resin is dispensed into themixing pot.

c) Catalyst may be added by hand or bymachine. Mix for one minute.



Page 10 of 24


Matrix Mixing Methods continued:d) Add background pigment by hand and

mix for one minute. May add smallamount of filler to help disperse thepigment.

e) Machine dispenses filler into the mixingpot. Mix until all is wet out.

f) Scrape down sides and mixing blade forunmixed materials.

g) Mix for additional three minutes toensure thorough mixing

h) Add veining pigment(s) if desired.i) Pour onto molds.

3) Auto-Casting Method—As the namesuggests, auto-casting equipment isdesigned to measure, mix, and dispensematrix directly onto the mold. The machineis programmed with a formulation. Itmeasures the heated resin, filler, catalyst,and background pigment. The materials are

dispensed into a tube called the barrel. Inthe barrel, there is an auger screw thatserves as the mixing mechanism andtransports the matrix through the tube.Veining pigment, if desired, may beautomatically added as the matrix nears theend of the barrel or may be hand-applied tothe mold. Once the matrix emerges from thebarrel, it falls onto the mold or can be put ina bucket and then hand-poured onto themold.

Like the auto-dispensing equipment, auto-casting equipment has resin heatingcapabilities which allow higher filler loading.The whole process is automated, reducingthe labor force. Matrix output is high, greaterthan 50 pounds per minute, which increasesproduct output. Finished product should beconsistent. No need for measuringmaterials. Keeping the machine calibrated iscritical.

Matrix Viscosity Temperature Vibration

• Thick matrix will produce

crisp sharp veins.

• Thin matrix will produce

blurred veins.

• Hot temperatures will decrease

or thin the matrix viscosity.

• Colder temperatures will

increase or thicken the matrix

viscosity.

• Long vibration time will produce blurred or less defined

veins.

• Short vibration time will produce crisp, sharp veins.

• It is important to keep the vibration time constant in order to

maintain consistent appearance.

F. Veining—Veining is an art that becomes anidentifying mark for each manufacturer. Veiningtechniques vary as widely as the resulting designs.No one method is better than another, it is purely asubjective preference.

The table below lists some factors that will influenceveining results.

G. Pouring Methods—Transferring the matrix fromthe mixing pot/bucket to the mold can be done usingpaddles, scoops, gloved hands, or simply pouringout of the bucket. Pouring method, again, is thepreference of the manufacturer based on thecosmetic appearance of his product.

In general, the veined matrix is applied on the moldfirst. Once the vein pattern is established, the

remaining matrix is transferred and fills up the mold.

1). Pouring Vanity Tops/Bowls

a) One-Pour Method—The full hat, in thiscase with a lip that covers the wholemold, is positioned and clamped intoplace to stop matrix leakage. The rest ofthe mold is then filled as necessary.Some techniques utilize overfilling of themold areas, followed by quicklyclamping down the hat to force the extramatrix into the bowl area of the hat.Vibration is continued an additional fiveminutes to ensure air removal.

b) Two-Pour Method—This method isrequired with partial hats. It is similar to



Page 11 of 24


Pouring Methods continued:

the one-pour up to the point of adding thehat. Also, the initial pour can be a higherviscosity because the semiclosed moldsituation in single pouring, which hampersflow and air release, is not a factor. Crisperveining will result. Once the cavities of thedeck are filled, along with a matrix cover of1/8 to 1/4 inch on the bowl area, a hat with a3 to 5 inch lip is positioned around the bowlarea only. This may be removable orpermanent. Once the first pour has gelledand has enough strength to hold the hat inplace to prevent leakage, the second mix ismade to fill the cavity of the hat. This mixcan be lower in viscosity to allow it to flowmore easily. It may be any color as it will notshow through the first layer of marble.

The second pour, to fill the hat, may beadded shortly after the first pour gels, or itmay be delayed until after the first pour hasexothermed. Timing of the second pour isimportant. If either pour shrinks significantlywhile the other pour is soft, cracking canresult. The catalyst level of the second pourmay be reduced to delay and lowerexotherm development.

2) Pouring Large Parts (tubs, shower pans,etc.)—Tub castings can present uniqueproblems because of their mass. The largerthe mass, the higher the exotherm duringcure. The high exotherm may lead toexcessive shrinkage and cracking. Tubsmay also vary in wall thickness, which canlead to differential shrinkage and cracking. Athicker area may begin shrinking and createa tear or crack if adjacent to a thinner, lesscured area. Tubs are often cast in multiplepours, which are catalyzed at different times.

The following are points to consider incasting tubs:

Catalyst Level

• Catalyzation should be appropriate for the

ambient temperature.

• Catalyst levels may range from 0.5 percent

in the hot summer months to 1.25 percent in

the cold winter months. The norm is approx-

imately 0.75 percent (based on resin

content).

• Low catalyst levels coupled with variable

thickness can contribute to cracking due to

low green strength development.

Special Formulated Tub Resins

• Tub resins are high viscosity versions of

marble resins. (With higher viscosity, there is

less styrene monomer in the resin.)

• Lower styrene content reduces the amount

of shrinkage during the cure.

• Also, it is desirable to have thick matrix

viscosity for tubs so that the matrix will

adhere to the mold during the mold filling

process.

Demolding

• Remove the hat as soon as allowable to

dissipate the exotherm.

• Suspend the mold so that the part is right-

side up one inch above the floor to allow

gravity to aid in demolding the part.

• Demold the part as soon as possible to

alleviate any stress on the matrix.

H. Vibration—The effect of vibration is a result oftime, frequency, and amplitude. Frequency is therate at which vibration occurs. Amplitude is thepower or energy of the vibration. Ideally, vibrationcauses the mold and matrix to resonate at thevibration frequency. Heavier parts and mold candampen the amplitude and make the vibrationineffective. Likewise, the vibrator motor can makeloud noises but not actually transfer its power(amplitude) to the mold. It is recommended to



Page 12 of 24


Vibration continued:

periodically check the effectiveness of the vibratormotor.

Vibration is used during the process of filling themold to help the matrix flow over the mold surface.As the matrix moves, filling the mold, air bubbles areable to come to the surface and break. Once themold is filled, the vibration continues to help theentrapped air move off the gel-coated side andmigrate to the back of the part.

Vibration should commence during the filling of themold and stop several minutes after the mold isfilled. Vibration should never continue once thematrix has gelled. Excess vibration can wash out thevein pattern and cause the filler to settle to the moldside, which can contribute to warping. If air bubblesare seen on the gel-coated side, it may be due toineffective vibration or vibration time that is too short.

I. Demolding—Once the matrix has gelled, themold should be trimmed. This requires removal ofthe tape, the overspray gel coat, and the matrix fromthe mold flange. This helps the gel coat to releasefrom the mold and reduces the potential problem ofedge peel. As the part cures and begins to shrink, itis good practice to remove the back hat (of a bowl),open the back splash, remove inserts, and eliminateother constraints as soon as possible. Do not forcethese parts off because that will stress and possiblycrack the part. During the curing process, the matrixwill release or shrink away from these parts and itsremoval should be relatively easy.

Demold the part as soon as possible to avoiddeveloping internal stress as the part shrinks on themale mold. In extreme cases, it is possible for thepart to shrink and lock itself onto the male mold. Asstated before, do not force the part out of the mold. Itshould release on its own. If it requires too muchenergy or pressure, then the part is not curedenough to come off. When working with large partssuch as tubs, the mold can be suspended upsidedown to allow gravity to demold the part.

Once the part is demolded, it should be supportedon templates or tables to reduce the possibility ofwarping while it is completing its cure. This isespecially critical if the demolded part is still very

‘green’ (flexible or soft).

J. Finishing and Repairing—Once the part iscured, it will need to be finished. Typical finishingincludes:

• Sanding the edges and the back orbottom of the part (smoothing off thesurfaces)

• Polishing the top surface (gel-coatedside)

• Drilling or smoothing the edges of thefaucet and drain holes

• Repair or patching of surface defects

If the defect is in the gel coat only, patch using thegel coat. If it is deeper, use catalyzed matrix almostto the surface. After it cures, patch with the gel coat.With granite or solid surface, repair using the matrixmix.

K. Influence of Temperature—Gel and cure of thegel coat and matrix are influenced by many factors;for example, catalyst levels, catalyst type, humidity,types of fillers, and pigments can shorten orlengthen gel times. Gel and cure rates can bemanipulated by variations of catalyst type and level.The use of higher catalyst levels produces faster geltimes but will also produce hotter cures. The use oflower catalyst levels produces slower gel times butwill also lengthen total cure times.

The most influential factor and the hardest to controlis temperature. Often, attention is given to thetemperature of the resin, but temperatures of thefillers, mold, and room are neglected. If the resin iswarmed to 100°F (38ºC) and it is mixed 75 percentwith filler at 50°F (10ºC), the combined matrixtemperature will be approximately 60 to 70°F (15 to21ºC). The gel and cure is further inhibited bypouring the matrix onto a 50°F (10ºC) mold sitting at50°F (10ºC) ambient temperature.

Heat is another catalyst to the cross-linking reaction.The exotherm generated by the reaction is neededto help drive the cure through. If the ambienttemperature and the materials are cold, theexotherm is lost to heating its surroundings. In coldtemperatures, viscosity of matrix thickens, curetimes are extended, and degree of cure issues andair entrapment problems are predominant. As



Page 13 of 24


Influence of Temperature continued:

ambient temperatures go up, matrix viscositydecreases and high exotherms and inconsistentshrinkage become the main problems. As catalystlevels and resin contents are lowered to account forthe higher temperatures, the green strengthdevelopment becomes affected, which can lead tocracking or tearing problems.

A crack is characterized by a sharp straight line andis primarily due to excessive shrinkage caused byhigh exotherms. Cracks can be controlled byreducing catalyst level and optimizing the filler toresin ratio. A tear will have a haphazard directionand is ‘whitish’ in color and appears in areas ofmaximum stress. Tears are primarily due to poorgreen strength development.

A mix will hold significantly more fillers at highertemperatures. For example, a resin adjusted to1,500 cps when used in a mix of 23 percent resin,and 26 percent fine and 51 percent coarse fillers hasa viscosity of 344,000 cps at 77°F (25ºC). The samemix at 99°F (37ºC) is only 152,000 cps and is toothin to be workable. Often times, mixing viscosity isfine-tuned by adding resin or filler. In this case,adding more filler will bring up the viscosity. As thisis done, resin percentage can drop to the pointwhere green strength development is significantlyslower, which can result in edge peel, stressing, andpossibly tearing of the part.

A recommended procedure would be to alter thecoarse-to-fine ratio to maintain proper matrixviscosity while maintaining the original resin content.It is advisable when using a two-component fillersystem to increase the percentage of fine fillerduring the hotter temperatures. A standard mix usinga two coarse-to-one fine filler ratio will require 2percent additional filler at 99°F (37ºC) versus 77°F(25ºC) to keep the same viscosity. At ambienttemperatures over 85°F (29ºC), fine fillers should beincreased to a ratio of three coarse-to-two fine fillers.If preblended fillers are used, it is suggested to keepbags of fine fillers available for such adjustments.

Another alternative to keeping mix viscosity constantwithout changing filler ratios at higher temperatureswould be to use higher viscosity resins. From themanufacturing side, whatever opportunities are

available to keep materials as cool as possibleshould be used. Problem parts should be cast duringthe coolest point of the day. Starting earlier andfinishing earlier for summer hours to take advantageof cooler mornings deserves strong consideration.

5. TROUBLESHOOTING GUIDE—This section providessome possible causes or explanations for typicalproblems encountered during production of cast polymerproducts.

A. Filler Particle Packing—Filler particle packingrefers to the distribution of the individual fillerparticles within the matrix. The looser thedistribution, the larger the spaces between particles.The tighter the distribution, the smaller the spacesbetween particles. Use of all coarse or large fillerparticles results in the loosest distribution ofparticles. Use of a combination of coarse and finefillers results in the tightest particle packing. See theFigure 7/II.1 and Figure 7/II.2 on the next page.

Tight filler particle packing in cast polymer productsenhances the performance of the finished part. Incast polymer products, resin fills in the gapsbetween particles. If the gaps are large enough, theresin may shrink and pull away from the fillerparticles creating small fissures within the matrix.This is referred to as resin laking. The fissurescaused by resin laking may go unnoticed until stressor impact, such as thermal cycling, causes it to opento a visible surface crack.

Filler particle packing and particle size also affectthe matrix viscosity. See Figure 7/II.3 on the nextpage. Use of all coarse filler particles will result inhigher viscosity due to poor packing. Use of all fineparticles will result in high viscosity due to poorparticle packing and high resin usage. Again a blendof coarse and fine particles is ideal. Use of two partscoarse and one part fine fillers will yield the lowestmatrix viscosity.



Page 14 of 24


Figure 7/11.1 - Poor filler particle packing.

Figure 7/11.2 - Good filler particle packing.

Figure 7/11.3

B. Temperature—Temperature affects theviscosity of the resin which can lead to changes inthe resin content of the matrix. The higher thetemperature, the lower the viscosity; the lower thetemperature, the higher the viscosity. Examples of

viscosity versus temperature relationships for tworesins are shown in Figures 7/II.4 and 7/II.5 on thenext page. Low temperatures affect the viscosity

Figure 7/11.4 - Viscosity poor filler particle packing data.

Figure 7/11.5 - Good filler particle packing data.

Figure 7/11.16



Page 15 of 24


Temperature continued:

much more dramatically than high temperatures.The higher the original resin viscosity the moretemperature changes will affect the viscosity.

Temperature also affects the matrix viscosity. SeeFigure 7/II.6 on the next page. Starting with resin at1,260 cps viscosity and blending 25 percent resinand 75 percent filler, the resulting matrix has a200,000 cps viscosity. When the temperatureincreases to 95ºF (35ºC), the 1260 cps resinviscosity can thin down to 600 cps. To get the same200,000 cps matrix viscosity using the 600 cpsviscosity resin, the matrix composition will be about22.7 percent resin and 77.3 percent filler. This is a2.3 percent resin reduction in the matrixcomposition. While 22 percent resin is acceptable,care must be taken if resin percent gets too low (lessthan 20 percent). Too low resin content may lowerthe finished product’s performance, such as thermalshock.

C. Cracking and Tearing—As temperaturesincrease, cracking and tearing problems will alsoincrease.

Cracks (sharp straight lines) are primarily due toexcessive shrinkage caused by high exotherm.

Tears (lines which are haphazard or lack direction,and may have frayed appearance) are primarily dueto low green strength* and will appear in areas ofmaximum stress.

Cracking and tearing can be avoided by adjustingfiller ratios in relationship to increases intemperature.

As temperature increases:

DO

NOT

Increase filler percent to increase matrix

viscosity.

- Increased filler percent will lower the

resin percent.

- Lower resin percent will reduce green

strength* development which can lead

to tearing.

DO Maintain resin percent and increase ratio of

fine fillers.

- Standard filler mix is two parts coarse

to one part fine.

- At temperatures over 90°F, a ratio of

three parts coarse to two parts fine will

maintain original viscosity.

DO Switch to higher viscosity resin.

- Allows use of standard filler mix (two

parts coarse to one part fine).

D. Gel Coat Delamination—This situation occurswhen gel coat adhesion to the mold is so strong thatthe matrix is not able to pull the gel coat free fromthe mold as it shrinks; subsequently, the matrix pullsaway from the gel coat.

Some possible solutions for gel coat delaminationare as follows:

1) Improve the mold release application orchange mold release type.

2) Increase in catalyst level of the gel coat toaccelerate the cure time. This will preventthe styrene from dissolving the releaseagent and improve the cure of the gel coatand increase shrinkage.

3) Take care to ensure the gel coat is sprayedon 20 to 25 mils wet (cures to 18 to 20 mils).Thin films cure slowly.

4) Use a resin with faster green strengthdevelopment.

E. Gel Coat Delamination on Edges of Part—Gelcoat delamination on the edges of a part has twoprimary causes. These causes along with solutionsare described as:

1) Gel Coat Overspray—Overspray tends to bethin and cures at a slower rate. Flange areastypically are not waxed and gel coat doesnot easily release from the surface.Adhesion of the gel coat to the unwaxedflange area of the mold is stronger than theadhesion of gel coat to matrix at the edge.Thus, upon demolding, the gel coat will peeloff the marble matrix edge.



Page 16 of 24


Gel Coat Delamination on Edges of Partcontinued:

To avoid this problem, tape the flange areasup to the edge of the marble part. Afterspraying the gel coat, remove the tape whilethe gel coat is still wet.

2) Thin Gel Coat on Vertical Edge—Gel coaton a vertical edge may be thin, causing it tocure at a slower rate and not shrink awayfrom the mold.

To check for this problem, measure the milthickness on the vertical edge to ensure thatit is the same as the rest of the part. Also,increase the catalyst level of the gel coat toaccelerate the cure time.

*WHAT IS GREEN STRENGTH?

In a filled polyester system, green strength is the

strength development between gelation and the point of

peak exotherm (cure rate). This is measured by the time

required from catalyzation to a measurable Barcol

hardness.

Soon after gelation, the matrix begins to shrink. It is not

immediately apparent due to the adhesion of the gel coat

to the mold. During the shrinking process, the strength is

building up to a point when it is able to sufficiently

overcome the adhesion of the gel coat to the mold.

Hence, the part releases from the mold. If the shrink rate

exceeds the strength development, tearing occurs.

Slow green strength development may be caused by:

1. Slow reactive resin

2. Cold resin, fillers, mold, shop

3. Catalyst level too low or wrong type

4. Filler loading too high

5. Moisture in the fillers

6. Influence of pigment

F. Prerelease of gel coat on bowl perimeter andedges of parts—Prerelease of gel coat on bowlperimeter and edges of parts has a number ofpotential causes. These causes along with solutionsare described as follows:

1) Uneven Gel Coat Thickness—The gel coatmay be too thick in the creases due todrainage. These thicker areas will curefaster and have a higher shrink rate. Toavoid, check gel coat thickness whilespraying. Keep spraying as evenly aspossible (20 to 25 mils wet).

2) Motion—If using floating bowls which are notsecured, movement or vibration will causethe bowl and gel coat to move and releasefrom the mold surface. To avoid, make sureall mold parts and edges are secured.

3) Prerelease When Using Clay—When usingclay around the bowl perimeter and edges,oils from the clay can cause prerelease ofthe gel coat. Potential for this problem ismagnified in the summer months, as hottertemperatures soften the clay and releasemore oils to the surface. These oils serve asmold releasing agents to the gel coat. Takeone or more of these steps to avoid thisproblem:

a) Keep clay as cool as possible.When cold, the oils remain in theclay and are not drawn to thesurface.

b) After placing the clay on the mold,lightly sprinkle talc or powder on it toabsorb the oils. Be sure to blow offthe excess powder.

c) After placing the clay on the mold,put a layer of mold release on theclay; this will help seal in the oils.

d) Before applying the clay onto themold, draw the oils out of the claywith a microwave oven. Put the clayon an unwaxed paper plate or papertowel and microwave for 30 to 60seconds. The oils will come to thesurface and be absorbed by thepaper. CAUTION: If microwavedtoo long, the clay will become dryand crumble.



Page 17 of 24


G. Gel Coat Stress Lines—The main cause ofstress lines is high gel coat adhesion to the moldwhich causes incremental release instead of asmooth continuous release.

To avoid, check the following areas:

1) Mold Releasea) Make sure molds have good layer of

mold release.b) Be sure mold release is applied properly

over entire mold, including the edges.2) Gel Coat

a) Make sure gel coat is sprayed evenlyover part (20 to 25 mils wet). Rememberthat thin films cure slowly.

b) Catalyze gel coat to get reasonably fastgel and cure. Slow gel times will allowgel coat to dissolve release agents.Overcatalyzing will cause too muchshrinkage.

c) Check catalyst line of spray gun to makesure catalyst is not ‘spitting’ and makinghot spots. Thick films will cure andshrink more.

3) Matrix Shrink Rate Greater than Gel CoatShrink Ratea) Reduce catalyst level of matrix to slow

down gel and cure rate.b) Use lower shrinkage resin.c) Reduce lightweight filler amount.

Lightweight filler increases peakexotherm, causing higher shrink rate.

d) Increase filler loading.e) Check fine to coarse filler ratio. Too

much coarse filler will increase numberof resin lakes between fillers andincrease shrinkage.

H. Cracking and Delamination of White GelCoats —White gel coats (as opposed to clear gelcoats) are more heavily promoted and containtitanium dioxide (TiO2-white pigment). TiO2 inhibits(slows) the gel time; therefore, higher catalyst levelsare required.

Higher catalyst levels can lead to higher exothermthat in turn leads to exothermic cracking. On theother hand, if the catalyst level is not sufficient, thegel coat will cure very slowly. Upon curing of the

matrix, insufficiently cured gel coat may tear due tolow green strength and fail to release from the mold.

Once the gel process has occurred, because ofhigher promoter levels and extra catalyst, the curerate is quicker than with clear gel coats. If the gelcoat has overcured, the matrix will not bond well.Delamination will be further enhanced by the TiO2,which reduces the surface tack of the gel coat.

To avoid this problem, be sure to:

1) Determine the appropriate catalyst level.2) Be aware of the cure rate of the gel coat.3) Pour the matrix at the appropriate time.

I. Gel Time Too Fast or Too Slow—There arethree main factors that can promote too fast or tooslow gel time.

These influencing factors are:

1) Influence of Fillers and Pigmentsa) Change of filler sources.b) Change from coarse to fine particle

ratios (the more fine particles, theslower the gel time).

c) Moisture in filler (or resin) which willinhibit gel time.

d) Change in pigment colors andconcentration. Dark colored pigmentsand TiO2 inhibit gel time.

2) Influence of Temperaturea) As a rule of thumb, a resin temperature

increase of 18°F (-8ºC), will cut the geltime in half. A decrease of 11°F (-12ºC)in temperature will double the gel time.

b) Temperature of filler. If resin is warmand filler is cold, matrix is cold.

c) Mold temperatures. Cold molds will cooloff a warm matrix.

3) Influence of Catalysta) Change in catalyst supplier.b) Change of catalyst ratio.c) A change from or blend of MEKP

catalyst to 2,4-pentadione peroxide (2,4-PDO) catalyst, (i.e., Azox Trigonox-44).A 2,4-PDO catalyst will have a slowergel time but a faster relative cure.



Page 18 of 24


J. Too fast or too slow cure times have twoprimary causes. These causes along with solutionsare described below.

1) Influence of Pigments, Fillers, Temperature,and Catalysta) Any influence of the above factors that

affect gel time will also affect cure time.NOTE: Gel and cure times are directlyrelated. The faster the gel time, thefaster the cure time.

b) Use of lightweight fillers tends toincrease peak exotherm and cause afaster cure rate.

2) Casting Size and Thickness (the larger andthicker the part, the faster it cures and thehigher the peak exotherm)a) Lower the catalyst level or use a ‘cooler’

catalyst.b) Remove or open molds as soon as

possible.c) Use air or water to dissipate the heat

from the surface of the part.

K. Warpage—Warpage has two basic causes.These causes along with solutions are describedbelow.

1) Filler Settling—This produces resin-richbacks, which cure, shrink, and pull inwardcausing the parts to warp upward in themold. Solutions include:a) Increase fine filler particles to increase

or thicken the matrix viscosity.b) Increase total filler loading to increase or

thicken the matrix viscosity.c) Reduce vibration time to reduce the

chance of filler settling.d) Increase the catalyst level to shorten the

gel time.2) Excessive Shrinkage—Excessive shrinkage

causes warpage on the decks around thebowl. Solutions are described as follows:a) Increase filler loading. The lower the

resin content in the composition, thelower the peak exotherm and shrinkage.

b) Check fine to coarse filler ratio. Toomuch coarse filler will increase thenumber of resin lakes and increaseshrinkage.

c) Reduce the catalyst level. The longerthe gel time, the lower the peakexotherm.

d) If back-pouring the bowls, reduce thecatalyst level in the second pour. Theexotherm of the first pour will helpcatalyze the second pour.

e) Remove the parts from the mold whilestill warm and support it right side up tocounter the warpage.

f) Check mold release application to makesure it’s not a prerelease problem.

3) Post Demold Warpage—Warpage of partsafter demolding due to lack of full cure canbe avoided by the following:a) Lay the part down so that it is better and

fully supported until cured.b) Increase the catalyst level to quicken

the cure or try a secondary curingcatalyst such as a 2,4-pentadionecatalyst (Azox, Trigonox-44, etc.)

c) Check the mixing procedure and makesure the catalyst amount is bothmeasurable and a large enough quantityto ensure a good even distributionthroughout the matrix.

L. Cracking—Cracking is mainly caused byunrelieved cure shrinkage stress which exceeds thegreen strength of the resin. Solutions to this probleminclude:

1) Reduce Matrix Shrinkagea) Increase filler loading.b) Use lower shrinkage resin.c) Cure matrix slower by reducing or

changing catalyst.d) For tubs and shower pans, use higher

viscosity resin.2) Increase Matrix Crack Resistance

a) Increase green strength by doing one ofthe following:a1) Use hotter catalyst or increase

catalyst level.a2) Use 2,4-Pentadione type catalyst.

b) Increase matrix elongation.b1) Use higher elongation resin.b2) If using lightweight fillers, try using

lightweight fillers with added



Page 19 of 24


Cracking continued:elongation or glass fibers (e.g., R. J.Marshall Thermolite 100).

c) Relieve stress by allowing the part tomove as it shrinks.c1) Remove hats, open back splashes.c2) Check mold release.c3) Check gel coat gel and cure.c4) Check mold design.

M. Air Bubble Entrapment—Air bubbleentrapment has three possible causes. Thesecauses and suggested solutions follow.

1) Matrix Viscosity Too Higha) Check temperature of resin, fillers, shop,

and mold. The colder it is, the thickerthe matrix.

b) Check for high concentration of fine fillerparticles. The higher the quantity of fineparticles, the thicker the mix.

c) Increase the resin ratio of the mix.d) Use lower viscosity resin.e) Add wetting and air release agents to

the resin.2) Ineffective Vibration

a) Check for sufficient and uniformvibration force around the table.

b) Lower catalyst level to decrease geltime and allow more time for vibration.

3) Catalyst Reaction with Pigment and/or FillerGenerating Gas Bubblesa) Mix catalyst thoroughly into resin before

adding dry pigment and filler.b) Make sure all dry pigment and fillers are

thoroughly dispersed (no lumps) beforeaddition of the catalyst.

N. Soft Spots—Soft spots are caused by resin thathas not gelled or cured evenly. Possible solutionsare:

1) Increase catalyst levels, using lower-strength catalyst and increasing volume.

2) Mix catalyst to resin thoroughly beforeadding filler.

3) Check for moisture in filler (wet filler tends toclump; water retards gel and cure).

4) Check for pockets of unmixed pigment.

O. Blurred Vein Lines—Blurred vein lines are

caused by matrix mix that is too low in viscosity. Thisproblem can by resolved as follows:

1) Increase filler ratio.2) Increase catalyst level.3) Reduce vibration time.

P. ‘Guesstimating’ Resin Gel Time—Temperature versus resin gel time is an exponentialrelationship (see graph on this page). For example,if a resin gel time at 70°F (21ºC) equals 15 minutes,what would the gel time be at 60°F (15ºC) or 80°F(27ºC)? The formula is:

Use 60 – 70 = -10

Multiplying factor for -10 = 1.90 (see chart)

15 X 1.90 = 28.5

Gel time at 60°F (15ºC) = 28.5 minutes.

Use 80 – 70 = +10

Multiplying factor for +10 = 0.68 (see chart)

15 X 0.68 = 10.2

Gel time at 80°F (27ºC) = 10.2 minutes.

As a general rule of thumb, for every 11°F (-12ºC)

decrease in temperature, the gel time doubles (2x).

For every 18ºF (8ºC) increase in temperature, the

gel time halves (0.5x).



Page 20 of 24


RESIN GEL TIME GUESSTIMATOR

Temperature

Difference

Multiplying

Factor

Temperature

Difference

Multiplying

Factor

-2

-4

-6

-8

-10

-12

-14

-16

-18

-20

1.15

1.31

1.51

1.67

1.90

2.09

2.31

2.59

2.95

3.46

+2

+4

+6

+8

+10

+12

+14

+16

+18

+20

0.92

0.85

0.79

0.73

0.68

0.62

0.58

0.53

0.50

0.45

Q. Catalyst Ratio—Remember that increased

temperatures can cause high exotherms and increase

shrinkage, which will result in cracking. When

temperatures increase:

DO NOT DO

Reduce the catalyst

level.

- Catalyst amount

may be too small to

disperse thoroughly

in the mix.

- This will slow green

strength

development.

- Full cure may not be

achieved.

Change to a lower strength

catalyst.

- This allows an increase in

catalyst amount for better

mixing and to ensure full

cure.

Switch to a longer gel time

resin.

- Allows an increase in

catalyst percent or …

- Maintains ‘normal’

catalyst percent.

The general rule of thumb for catalyst ratio is that

the level should be maintained between 0.5 percent

minimum and 3 percent maximum.

As the catalyst level moves outside this range,

change, as appropriate, to a cooler or hotter catalyst

type.

6. SUPPLIES FOR MARBLE PRODUCTION—CookComposites and Polymers supplies gel coats, resins,and cleaners for cast polymer production. Otherresources are listed here:

A. Mold ManufacturersGruber Systems25636 Avenue StanfordValencia, CA 91355-1117Ph: 800-257-4070

661-257-4060Fax: 661-257-4791www.gruber-systems.com

J. R. Composites Inc.1251 GoForth RoadKyle, TX 78640Ph: 800-525-3587

512-268-0326www.JrComposites.com

Ken Fritz Tooling & Design, Inc.1945 Puddledock RoadPetersburg, VA 23803Ph: 800-426-1828

804-862-4155Fax: [email protected]

B. Filler SuppliersAlcan Specialty Aluminas6150 Parkland Blvd.Suite 220Cleveland, OH 44124Ph: 440-460-2600Fax: 440-460-2602www.Riotinto.com/riotintoalcan

Imerys100 Mansell Court East, Ste 300Roswell, GA 30076Ph: 888-277-9636

770-645-3700Fax: 770-645-3384www.imerys-perfmins.com

R. J. Marshall Company26776 W. 12 Mile RoadSouthfield, MI 48034Ph: 800-338-7900

248-353-4100



Page 21 of 24


Fax: 248-948-6460www.rjmarshall.com

ACS International4775 South 3rd AvenueTucson, AZ 85714Ph: 800-669-9214

520-889-1933Fax: 520-889-6782www.acstone.com

Huber Engineered Materials1000 Parkwood Circle Ste 1000Atlanta, GA 30339Ph: 678-247-7300Fax: 678-247-2797www.hubermaterials.com

Filler Suppliers continued:Sanco Inc.207 Brookhollow Industrial Blvd.Dalton, GA 30721Ph: 800-536-5725

706-279-3773

C. Dry Pigment and Pigment DispersionSuppliers

American Colors1110 Edgewater DriveSandusky, OH 44870Ph: 419-621-4000Fax: 419-625-3979www.americancolors.com

BroCom Corp.2618 Durango DriveColorado Springs, CO 80910Ph: 888-392-5808

719-392-5537Fax: 719-392-5540www.marblecolors.com

Plasticolors2600 Michigan Ave.P.O. Box 816Ashtabula, OH 44005Ph: 888-997-5137

440-997-5137Fax: 440-992-3613

www.plasticolors.com



Page 22 of 24




Page 23 of 24







Page 24 of 24

CASTING: Solid Surface

Composites

Applications Guide

Part Seven, Chapter IIICopyright 2008


2. Materials

3. Manufacturing Process

4. Matrix Formulation

5. Postcuring

1. INTRODUCTION—Solid surface is a specializedcasting application characterized by its homogenouscomposition and the absence of gel coat. Homogeneityis required for fabrication of solid surface parts sinceinstallation may include routing, cutting, surface sanding,creating inlaid designs, and edge shaping. As a result,each side of a solid surface part is potentially a finishedside, including the cut edges. Solid surface parts can bepigmented or veined and are slightly translucent or havea granite appearance.

One of the main defects found in solid surface parts arevoids. If the matrix contains voids, some will likely beexposed during the installation/fabrication process.Exposed voids become visible defects and aresusceptible to staining. Materials used, matrix mixingprocedures, and matrix formulation all influence voidcontent.

2. MATERIALS—Solid surface resins are based onISO/NPG polyesters similar to those used in gel coatsrather than the orthophthalic type resins used in gel-coated casting applications. This higher grade matrixresin is required since it must provide all the protectionthat would have been provided by the gel coat. (Foradditional information on resin chemistry see Part Three,Chapter II.) As with cultured onyx, clarity and low curedcasting color are very important factors. Solid surfaceresins are highly promoted to achieve reasonable curerates while using the fine particle size ATH fillers.However, the promotion system differs from culturedmarble in that the cured casting color is not as dark. Airrelease and wetting agents are typically added to help

release air bubbles/voids from the mix. UV stabilizersare added to improve UV stability. MMA (methylmethacrylate) may be added to improve UV and waterresistance.

Aluminum trihydrate (ATH) is the preferred filler for solidsurface products. Solid surface grade ATH is a muchfiner particle size than for onyx grade. Its size ismeasured in units called microns. The finer or smallerthe particle size, the whiter the cured casting color andthe tighter the particle packing. Tighter particle packingleads to increased surface hardness and a smoother,glass-like surface. ATH is also chemical resistant whichadds to the stain resistance properties of the part.Because of the ATH particle size, there is a high resindemand to wet out the fillers. Also, specially formulatedgranite effect fillers are available for solid surface.

Catalysts/Initiators used in solid surface production aresimilar to those used in cast polymer applications.

3. MANUFACTURING PROCESS—The generalfabrication process for solid surface production is shownin the chart in the column at right.

Solid Surface Mix Procedure

1. Weigh out the ingredients.

2. Add resin to the mixing pot.

3. May add catalyst to the resin and mix well for one

minute OR add catalyst at a later step.

4. Add pigment and mix well. May add small amount of

filler to help disperse the pigment.

5. Add filler and mix well.

6. Stop mixer and scrape down sides and mixing blade

for unmixed material.

7. Mix well for additional 3 minutes.



Page 1 of 4

CASTING: Solid SurfaceCopyright 2008

8. Apply vacuum; vacuum should be maintained at

least 5 minutes once 25 to 27 mmHg is reached.

9. If catalyst has not already been added in Step 3, add

catalyst to the mix.

10

.

Mix for 30 seconds without vacuum to blend in

catalyst.

11

.

Apply vacuum and maintain for 5 minutes.

12 Pour into molds.

Use of a vacuum mixer is recommended to aid ineliminating entrapped air in the matrix and voids in thefinished part. Vacuum mixers have been specificallydesigned for manufacturing solid surface. A vacuum with25-27 mmHg is recommended. Less than 23 mmHgvacuum is not effective, while more than 28 mmHg willcause monomers in the resin to vaporize. Monomervaporization would result in millions of microscopic airbubbles in the matrix that would be impossible toeliminate.

4. MATRIX FORMULATION—With solid surface, resincontent is much higher than other casting forms due tothe fine grind of the solid surface ATH filler and thenecessity to release air bubbles. Also, because of thefine grind of the ATH filler, a higher catalyst level isneeded. A typical solid surface matrix formulation is:

Resin 38-45%

Solid Surface Grade

ATH

55-62%

Base Pigment 1.0-1.5%

Initiator/Catalyst 1.0-3.5%

(based on resin content)

5. POSTCURING—To postcure is to expose a roomtemperature cured part to an elevated temperature for aperiod of time. The theory of postcuring is that theelevated temperature will increase the amount of cross-linking of the polyester resin. All cast polymer productsare cured at room (ambient) temperature; however, theroom temperature will change depending on the season.If the ambient temperature is cold, the polymer reactionwill slow down, resulting in longer gel and cure times.The longer the cure time, the harder it is for the part toreach a complete cure. Even in warmer ambienttemperatures, there are numerous factors that willprevent the part from achieving a full cure. Postcuringensures that all parts consistently achieve a completecure.

Postcuring is a necessity for solid surface products.Postcuring will optimize the physical properties whichare critical to meeting standards and certification testing.Studies have shown that physical properties such asflexural and tensile strengths and heat distortiontemperatures improve with postcuring. Also, chemicalresistance, water resistance, and UV stability of the finalproduct are enhanced. Postcuring also reduces theamount of residual styrene left in the part.

Recommended post-cure temperature is 180°F to 200°Ffor two to four hours. Do not allow temperatures above225ºF since this approaches the temperature at whichsolid surface begins to degrade and discolor. It isimportant that the elevated temperature is uniform in thepostcuring area. If there are ‘hot spots,’ there is a riskthat a part or a portion of a part will degrade or discolor.Postcuring is more beneficial when parts are postcuredimmediately after demolding (i.e., while the part is stillwarm and coming down off the peak exotherm) thanpostcuring a part that has completely cooled to roomtemperature. While being postcured, the part should bewell supported. No matter when a part is postcured—after demolding, the next day, or later—the benefits ofpostcuring will always exceed not postcuring.



Page 2 of 4

CASTING: Solid SurfaceCopyright 2008



Page 3 of 4







Page 4 of 4

CASTING: Flexible Casting Resins


Part Seven, Chapter IVCopyright 2008


2. Materials

3. Processing Information

4. Formulations for Flex Trim Molding

1. INTRODUCTION—Flexible resin is a specialpolyester resin formulated to achieve its flexibleproperty. There are several uses for flexible resins:

• Decorative trim molding—flex resin is mixed withvarious types of fillers and pigments, typicallycast in long strips. Required properties for trimmolding products include:

— Flexibility—strips of molding are rolled forpackaging. Trim needs to bend aroundstructural curvatures.

— Nailability—nails are used to secure moldingin place.

— Paintability—once installed, moldings arepainted.

• Safety glass—flex resin is poured between glassplates to prevent the glass from shattering uponbreaking.

• Blending resin—the most popular usage offlexible casting resins is in blending with anotherrigid polyester resin to increase the tensileelongation (flexibility) of the rigid resin. Theblending ratio is dependent upon the desiredflexibility. Increasing the flexibility will improvethe ‘toughness’ by decreasing the ‘brittleness’ ofthe part.

General characteristics of flexible resins are as follows:

• Very low shrinkage• Tacky surface finish• High tensile elongation• Low heat distortion temperature (HDT)• Low Barcol hardness

• Poor UV resistance.

Flexible resin by itself or blended in high ratios is NOTrecommended for use in structural parts or for use withgel coats. The high tensile elongation, low heat distortiontemperature, and low Barcol hardness will not providestructural integrity. Gel coat is typically rigid and cancrack if there is too much movement in the matrix orlaminate behind it.

2. MATERIALS—Flex resins are available in pre-promoted and unpromoted versions. The pre-promotedversions require only the addition of catalyst to start thecuring process. The curing process can be started forunpromoted versions by either use of heat and a heat-activated catalyst or use of catalyst and promoters atroom temperature.

• Benzoyl peroxide (BPO) catalyst is the mostcommonly used heat-activated catalyst and istypically used at temperatures above 200ºF.

• BPO may also be used to cure polyesters atroom temperature, provided an amine promoteris used. Examples would include diethylaniline(DEA) or dimethylaniline (DMA). DMA yieldsshorter gel times than DEA. More amine speedsup both gel and cure rates. Castings cured thisway tend to be more flexible. Instances wherethis cure system might be used are in two-potsystems where catalyzed resin and promotedresins are mixed just before or during usage.BPO is a paste and therefore less convenient touse than methyl ethyl ketone peroxide (MEKP).

• The most common system used for roomtemperature cure is MEKP catalyst with a cobaltpromoter. Use of a co-promoter amine isfrequently desirable to provide faster gel andcure rates for production needs. Typicalconcentrations would include 0.15 to 0.25percent of a 12 percent cobalt solution and0.025 to 0.25 percent DMA. Additional inhibitormay be added to achieve a specific gel time,once the right cure rate has been determined.



Page 1 of 5

CASTING: Flexible Casting ResinsCopyright 2008

CAUTION: When promoting polyester resins,promoters and catalysts must NOT come into directcontact with each other because rapid and violentdecomposition may result. The resulting by-productmay pose serious health and fire hazards.

Fillers are used to extend the resin, thereby lowering rawmaterial costs. Fillers impart color and opacity to acasting. Many inorganic fillers are white to light gray in aresin system. Organic fillers produce brown colors.Pigments can also be used to produce any desired color.

A. Inorganic Fillers—Typical inorganic fillers arecalcium carbonate, talc (magnesium silicate), andaluminum trihydrate. The two primary reasons forusing this type of filler are low cost and availability.Some fillers affect the final cured properties andneed to be checked by the end user for acceptableresults. Since these are heavy fillers, parts willreflect higher densities. Use of this type of fillermakes a part harder and less flexible. Aluminumtrihydrate can reduce the flammability characteristicsof the final casting.

B. Organic Fillers—Organic fillers are usuallycomposed of agricultural by-products that areground to various particle sizes. Because they areagricultural by-products, availability and consistencymay vary relative to geographic area. Typical fillersinclude ground pecan or walnut shells. Parts madewith organic fillers result in a wood-like finish andcan be painted. Careful selection of organic fillers isnecessary. Many organic fillers inhibit gel and cure,in some cases, very severely. Sawdust is a commonmaterial that is not recommended.

C. Lightweight Fillers—Use of lightweight fillerscan reduce cured densities close to that of wood.Lightweight fillers are hollow spheres that displaceweight but not volume and thereby effectively reducethe part’s density. There are various lightweight fillercompositions available as well as pre-blendedmixtures with calcium carbonate. Be aware thatsome types of lightweight fillers are fragile andreadily break. Once broken, these lightweight fillersbecome fine particles and advantage of lighterweight is lost.

Chopped fiberglass, milled fibers, wood, or metal rodscan be used to reinforce structural parts. Fibers aremixed into the resin to produce a higher physicalstrength part. Wood, such as particleboard or plywood

sheets, can be used as a back support. It is important tomake sure the wood is dry. Metal rods inserted into thecasting will impart stiffness.

3. PROCESSING INFORMATION—Molds must beflexible and strong for long life and ease in removing thecast part. In addition, they must be resistant to solventsand styrene. Mold materials must be capable ofduplicating every detail from the master. Typical mold-making materials are RTV silicone rubber, urethaneelastomers, and latex or vinyl rubber. NOTE: Latex mustbe non-sulfur based. Sulfur based latex will inhibit thegel and cure of polyester resins.

Castings pulled from the mold usually will have a slightlytacky surface. This tackiness is mostly unreactedstyrene monomer. Hot soapy water or solvent wash willeasily remove it. Castings can then be sanded, buffed,and polished to a variety of surface finishes from glossyto matte. Castings can also be painted, stained,lacquered, or varnished.

4. FORMULATIONS FOR FLEX TRIM MOLDING—Typical properties of CCP STYPOL

®flexible resin are:

Properties

Viscosity (Brookfield) 80 cps

Gel Time at 77ºF 3.5 minutes

Cure Time 10 minutes

Peak Exotherm 330ºF (166ºC)

Weight per Gallon 9.4 pounds

The following formulations are starting guidelines:

Flexible Parts

Resin 91.3%

Pecan Shell 2.2%

Calcium Carbonate 6.5%

Promoters as needed

MEKP 1% minimum



Page 2 of 5


Semi-Rigid Parts (nailable)

Resin 80.0%

Pecan Shell 20.0%

Pigments as needed

Promoters as needed

MEKP 1% minimum

Lightweight Parts (semi-rigid and nailable)

Resin 73.0%

Pecan Shell 19.0%

Lightweight Filler 8.0%

Pigments as needed

Promoters as needed

MEKP 1% minimum

Rigid

Resin 57.8%

Pecan Shell 42.2%

Pigments as needed

Promoters as needed

MEKP 1% minimum



Page 3 of 5




Page 4 of 5







Page 5 of 5

CASTING: Thermal Shock Testing Request


Part Seven, Chapter V

Copyright 2008

In This Chapter:1. Thermal Shock Testing

2. Factors Affecting Thermal Shock Performance

3. Thermal Shock Test Request

1. THERMAL SHOCK TESTING—Thermal shock is anaccelerated test designed to measure the longevity ofcast and solid surface parts when exposed to waterconditions of a typical home. Parts tested for thermalshock are typically kitchen sinks and bathroom sinks andtubs. Thermal shock testing is a required protocol ofANSI standards Z 124.3 for plastic lavatories and Z124.6 for plastic sinks.

During the thermal shock test, the part is exposed tocycles of extreme hot and cold water. The timeexposure, rate of flow, and water temperatures arespecific to each standard or test method. During the hotwater exposure, the part will expand or contract. Thenthe cold water will shrink or constrict the part. As aresult, the part will continuously ‘move’ by contractingand constricting throughout the test period.

Eventually, the part will reach a point of fatigue and failas indicated by the visible appearance of a crack. If thetest is permitted to continue, the crack will grow longerand deeper and other cracks can appear. Results aregenerally reported as the number of cycles to failure,along with a description of the failure, including whetherthe failure occurred in the gel coat or in the matrix.Thermal shock testing results have not been correlatedto the actual real time performance of the product.

2. FACTORS AFFECTING THERMAL SHOCKPERFORMANCE—Although thermal shock testingresults can be influenced by the quality of materials usedto fabricate the part, the manufacturing process used tofabricate the part is the main factor influencing results.

If thermal shock testing is being performed to qualify anew raw material, two parts should be made, one with

the ‘new’ material and one with the ‘old’ material, usingthe same manufacturing process. Results should becompared only to each other. If the results differ, thenthe difference is most likely influenced by the rawmaterial. However, very significantly different resultswould indicate a possible manufacturing defect in thepart with the lower result. If both results are equal butare very low (not meeting required number of cycles), amanufacturing process issue is indicated.

When performing thermal shock testing to becomequalified to a standard, it is assumed that the tested sinkor tub is a typical representative of the manufacturer’sproduct. Failure during thermal shock testing can occurin either the gel coat or the matrix. Descriptions of eachof these failure modes and possible causes for failurefollow.

A. Gel Coat Failure—Short cracks or crazing onlyin the gel coat layer indicate gel coat failure. Iftesting continues after gel coat failure has occurred,water will eventually seep under the crazed areas ofthe gel coat and cause it to peel. The exposedmatrix will eventually crack. Gel coat failures can becaused by porosity in the gel coat, or by thick, thin,or uneven gel coat thickness.

1) Porosity—When exposed to hot water,porosity or entrapped air in the gel coat layerexpands more than the surrounding gelcoat. Because the gel coat is such a thinlayer, it does not require many cycles of hotwater before a crack appears. The size ofthe air bubble will also make a difference inhow quickly the failure occurs.



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CASTING: Thermal Shock Testing RequestCopyright 2008

Gel Coat Failure continued:

2) Thick or Thin Gel Coat—If the gel coat layeris too thin, failures typically occur becausethe gel coat lacks the strength to withstandthe stress of the contraction. It the gel coatlayer is too thick, performance is better;however, as a result of the excessthickness, increased movement duringcontraction/constriction can fatigue the partand cause premature cracking.

3) Uneven Gel Coat—If the gel coat is notapplied evenly, areas of thin and thick gelcoat will contract and constrict at differingrates causing the interfaces where thick andthin areas meet to become high stressareas.

B. Matrix Failure—Cracks resulting from matrixfailure are deeper, longer, and most often wider thangel coat failure cracks. Typical matrix cracks radiatestraight out from the drain because the drain is thethickest section of the bowl. Matrix failure can becaused by matrix composition, reactivity of the backpour, porosity, misalignment of back (bowl) hats, orimproper placement of the overflow tube.

1) Matrix Composition—During the thermalshock test, the resin is the only material inthe matrix composition that contracts andconstricts. If the matrix is resin-rich, therewill be an excessive amount of movement inthe contraction and constriction. If the matrixis resin-poor, it will not hold together.

2) Reactivity of the Back Pour—Frequently,matrix resin content is increased for theback pour to make it easier to fill in the hats.High matrix resin content coupled with thethicker mass of the bowl will cause theexotherm of the back pour/hat to be veryhigh. The higher the exotherm, the greaterthe possibility of building in stress fracturesin the matrix during the curing process. Thestress fractures will grow during the thermalshock test and eventually become visible onthe surface.

3) Porosity—If there is entrapped air in thematrix near the gel coat interface, the hot

water exposure can heat the air within thevoid causing it to expand. This expansioncan cause a crack in the matrix which thenradiates to the surface

4) Misalignment Back (Bowl) Hats—Misalignment of back (bowl) hats will shiftthe mass of the matrix. The result will beeven greater differences between thick andthin matrix areas. Just like uneven gel coatthickness, there is a difference in the rate ofcontraction and constriction between thickand thin matrix areas, with the stress beingat the interface between the areas.

5) Improper Placement of Overflow Tube—Thespace under the overflow tube should beconsistent from the drain to the connectionnear the bowl’s edge. Matrix fills the gapbetween the bowl and the tube. If the spaceunder the tube is not consistent, thicknessvariations will occur and cause failure asdescribed above.

As stated previously, thermal shock testing is anindicator of how well the part was manufactured. It is anaccelerated method of testing with harsh and extremeconditions designed to push the performance of the part.If results are good, then the manufacturer has the peaceof mind of knowing that the production process isworking well. If results are poor, then it is importantinformation in defining the issues that need to beaddressed and corrected in the manufacturing process.

3. THERMAL SHOCK TEST REQUEST—CCPprovides thermal shock testing as a service to itscustomers. To request the test, please fill out thefollowing page and send with the item to be tested to:

CCPAttn: Composites In-House Tech Service Dept.820 East 14th StreetNorth Kansas City, MO 64116

Inquiries should be directed to:Ph: 816-391-6088Fax: 816-391-6215

Testing can be performed to either the ANSI Z 124.3or the ANSI Z 124.6 standards.



Page 2 of 5


THERMAL SHOCK TEST REQUEST continued:

1) ANSI Z 124.3 (Bathroom)—The standardtest uses 150ºF (66ºC) and 50ºF (10ºC)water. One cycle consists of:

1. 90 seconds of 150ºF (66ºC) water

flowing at one gallon per minute.

2. 30 seconds of drain time.

3. 90 seconds of 50ºF (10ºC) water

flowing at one gallon per minute.

4. 30 seconds of drain time.

To pass this test, a minimum of 500 cycleswithout cracks or blisters is required. Typically, bowltests are run until at least two cracks are observed.The bowl is then cut. The cracks are inspected andthe gel coat thickness is measured.

2) ANSI Z 124.6 (Kitchen)—This test uses190ºF (88ºC) and 70ºF (21ºC) water flowing at 1gallon per minute without pause between cycles.Passing requirement is 250 cycles minimum withoutcracks or blisters.



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Page 5 of 5

POLYESTER TOOLING: Introduction


Part Eight, Chapter ICopyright 2008

In Part EightChapter I. Introduction

Chapter II. The Master Model

Chapter III. Master Model Preparation

Chapter IV. Applying Release Wax to

Models and Molds

Chapter V. Building a Mold

Chapter VI. Mold Surface Distortion

Chapter VII. Mold Break-In Procedures

Chapter VIII. Mold Maintenance

Chapter IX. Mold Resurfacing

Chapter X. Mold Storage

Chapter XI. Special Precautions

Fiber reinforced plastic (FRP) parts are molded to thedesign shape using a tool (commonly called a mold) anda molding process. At minimum, a mold consists of amold skin, or molding surface. This surface’s qualitieswill be reflected in the molded part to be made in thetool. If the part requires a smooth, high gloss finish, thenthe molding surface needs to be a smooth high glossfinish.

The molding process has a large impact on the tooldesign. When a molding process involves highpressures, or when any mold deflection must be limited,bracing is used to reinforce the mold skin. This can beaccomplished with any combination of increasedthickness, the use of cores, and/or shaped stiffenerelements such as hat-section or c-section laminates.Each case of bracing can be unique in its design.

When a mold skin is larger than a few square feet, aframing system is also used to provide a means ofhandling the mold skin without causing it to be deformedor fractured. A framing system can be one of two types.The simplest framing system supports the dead weightof the mold and concentrates it on a few load points. Themore complex frames also provide structural support to

resist molding forces and restrict mold deformation. Bothsystems provide a means of grabbing the mold for liftingand transport operations.

Most mold skins used to produce FRP parts arefashioned from FRP-type materials. For high productionruns, a metal mold skin can be most economical, but ata higher up-front cost. An FRP-type mold skin isproduced using a master model, also known as a patternor plug. This master model is a full-scale representationof a part design that incorporates all of the geometry forone of the part surfaces. A model may be geometricallyequivalent to the part image or it can be a mirror imageabout the part’s external surface.

There is no quick or easy way to produce quality FRPtooling. Good tooling is a precise, painstaking craft. Itbegins with careful preparation of the master model andcontinues through the final building of the productionmold. Any defects on the master model will translateonto each subsequent piece of tooling and require extraeffort to remove. The highest quality production moldbegins with an even higher quality master model.

The terms master model, patterns and plug aresometimes used interchangeably. Due to recentadvancements in computer numerically controlled (CNC)routers, the term pattern generally describes a mastermodel that is machined from a blank constructed of asingle material or material type. In contrast, the termplug generally describes a master model that isconstructed from a variety of materials and shapedmanually. Neither a pattern nor a plug is particularlydurable and is suitable for producing only one, or a smallnumber of moldings. When two or more molds arerequired to meet production requirements, a mastermold is used to produce the production molds. Thismaster mold is a durable, robust, full-scalerepresentation of a part image design and is constructedin the same manner as a production mold.



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POLYESTER TOOLING: IntroductionCopyright 2008



Page 2 of 3







Page 3 of 3

POLYESTER TOOLING: The Master Model


Part Eight, Chapter IICopyright 2008


2. Number of Moldings

3. Surface Quality

4. Generator

1. INTRODUCTION—A wide variety of materials canbe used to construct the master model. Some examplesare plaster, polyester resin, epoxy resin, urethane foam,polyvinyl chloride (PVC) foam, body filler, FRP materials,wood coated with epoxy or polyester resin, medium-density fiberboard (MDF), and certain laminatedMelamine

®-faced sheet materials such as Formica

®or

bathroom wallboard.

2. NUMBER OF MOLDINGS—The number ofmoldings expected from the master model will influencethe choice of materials and construction methodology.Plaster or foam-board type patterns, or plugsconstructed from numerous materials will seldom surviveone pull without incurring some damage. If severalmolds are needed, it is best to build a master mold usingFRP materials. A master mold is robust and can be usedto produce a large number of production molds.

3. SURFACE QUALITY—The surface quality of themaster model is its most important feature for mostmolded FRP parts. It should be hard, glossy, and free ofdefects. The molding process will reproduce and worsenany defects on the master model. CCP tooling gel coat

makes an excellent final coating for the master model.When properly applied, tooling gel coat provides themost foolproof surface (see DS-45 Tooling Gel CoatData Sheets for specific information).

Resin shrinkage during the molding process will result ina part that is smaller than the master model. For someparts that require precise dimensions, the master modelmay be made slightly larger to offset this shrinkage . Theexact amount will depend on the type of resin and itsinherent shrinkage, the glass content, processtemperatures, and the number of generations betweenthe master model and the production part. A general ruleof thumb for conventional room-temperature curedpolyesters is 1/32 inch of shrinkage per linear foot whenreinforced with 25 weight percent glass content. Gel coatshrinks more than fiber-reinforced resin, resulting inparts that are more concave on the gel coat side. Forthis reason, any large, flat areas should be crowned in aconvex shape to prevent dishing in the reverse direction.A crown of 1/4 inch per linear foot is typical for smallpanels.

4. GENERATOR—The term generation refers to thenumber of successive moldings between the mastermodel and the production part. If a production mold ismade on the master model, it is a first-generationproduction mold. If a production mold is made from amaster mold that is made from the master model, it is asecond-generation production mold. A second-generation mold requires a master model geometry thatis a mirror image of the part design surface as describedin the schematic. Each subsequent generation can beslightly smaller than its predecessor. The exact amountwill depend upon the materials and processes involved.

Producing a master mold from the geometry of a mastermodel that is identical to the part design surface requiresan intermediate piece of tooling. This intermediate pieceis made from the master model and is called a zeromold. The zero mold is used to manufacture the mastermold. The master mold yields the production molds one,two, etc. Here, the zero mold is a first-generation mold,



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POLYESTER TOOLING: The Master ModelCopyright 2008

GENERATOR continued:the master mold is from the second generation, and allof the production molds (one, two, etc) are from the thirdgeneration.

Some materials used in the master mold may leavewitness lines in the subsequently molded FRP part. Thiscosmetic defect, known as mark-off, happens due to acombination of molding exotherm, substrate heatcapacity, substrate thermal expansion, cure shrinkage,and softening in the gel coat, both on the model andmolding. The zero mold presents an opportunity toremove these witness lines by wet sanding, buffing, andpolishing. This is particularly true for outside edges andcorners on the zero mold (convex, or ‘male’ typefeatures). Outside features are more easily sanded thaninside edges and corners (concave, or ‘female’ typefeatures). Defects at these inside edges and corners aremore easily corrected on the next piece of tooling, themaster mold, when they become outside edges andcorners.



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POLYESTER TOOLING: The Master ModelCopyright 2008



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Page 4 of 4

POLYESTER TOOLING: Master Model Preparation


Part Eight, Chapter IIICopyright 2008

In This Chapter1. Sanding

2. Polishing and Buffing

3. Test for Gloss

1. SANDING—A master model should be surfaced withtooling gel coat that is well-cured and sanded smooth. Ata minimum, sanding should be accomplished by usingfiner grit sandpapers until no scratches are present thatare deeper than those made by 600 grit paper. For ahigher gloss with less buffing, 800, 1000, 1200 and 1500grit papers are available. Each grit should be used at a90 degree angle to the direction of the preceding grit,until all of the crossing scratches are removed. A water-insoluble dye such as steel layout fluid (Dykem

®from

ITW) or a dry guide coat can be used to increase thevisibility of larger grit scratches, which should be sandeduntil they are eliminated before changing to the next finergrit paper. When wet sanding, a small amount of dishsoap helps to suspend sanding particles in the water.This water should be changed whenever moving to afiner grit paper to avoid subsequently scratching themodel surface with the sanding particles from thecoarser grit.

2. POLISHING AND BUFFING—After sanding, themodel surface should be polished and buffed using apolishing compound that is formulated for polyesters.Careful attention is needed in this operation. Poorpolishing caused by the high heat of the buffing pad canresult in orange peel, fiber print, and burn-through. Afterpolishing, wash the model with dish soap and water toremove residues from the buffing compound or polishingmedium.

3. TEST FOR GLOSS—After final polishing, check tosee if the tooling gel coat has a finished shine once allthe compounding materials have dried and beenstripped. Using a rag, lightly dampened with acetone orother suitable solvent, wipe the gel coat surface toremove any residue. The solvent should remove some ofthe residual compound oil, but the surface should havestill have a high gloss. If the tooling gel coat dulls down agreat deal, a lack of original gloss is indicated becausethe compound oil has produced an artificial gloss bywetting the surface and smoothing over anyimperfections.

To prevent damage to the tooling gel coat, do not allowacetone or other solvents to puddle upon, or to remain incontact with the model’s surface. Note also that moldrelease wax should not be used to increase gloss on amold surface. Waxes will raise the gloss of the moldsurface, but once coated with the gel coat can haze andare not durable. The mold surface should be sanded andpolished until the tooling gel coat has the degree of glossthat is required for the molded part.

Once the master model has been surfaced, sanded,buffed, polished, and washed with soap and water, amold release system should be applied.



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POLYESTER TOOLING: Master Model PreparationCopyright 2008



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Page 3 of 3

POLYESTER TOOLING: Applying Release Wax


Part Eight, Chapter IVCopyright 2008

In This Chapter1. Types of Mold Release

2. Application of Paste Wax

3. Additional Release Protection

4. Troubleshooting

1 TYPES OF MOLD RELEASE—The best results fortooling are achieved by using a good grade of paste waxformulated for FRP. It is imperative that the mastermodel or mold be thoroughly waxed to avoid any stickingduring demold of the part. At least six coats of waxshould be applied to the master mold to ensure acomplete release of the subsequent molded part.

If a polymer-based or semi-permanent mold releasesystem is used, follow the specific directions from themanufacturer. These systems usually include a surfacecleaner and a sealer that fills in the microscopic porosityand scratch. Most polymer mold release systems aredesigned for multiple pulls without updating the moldrelease system. This results in less mold maintenancetime and subsequently in increased productivity. For thepurposes of mold construction, this benefit is thoroughlyoutweighed by a specific detriment to polymer moldrelease. There is an increased risk of gel coat prereleasedue to the extraordinarily good release on the first partpull. (Usually, only one zero mold is pulled from a masterpattern and only one master mold is pulled from a zeromold, eliminating the benefit of multiple releases via apolymer mold release system.) For production moldspulled from a glass master, the cost of applying anadditional coat of paste wax between pulls is far lessthan the cost of correcting gel coat prerelease. It isalways a good idea to build a small test panel to be surethe system will produce moldings with the requiredquality.

2. APPLICATION OF PASTE WAX—Apply the firstcoat of release wax in a circular motion, taking care notto apply the release wax too heavily. Wait the amount of

time recommended by the manufacturer for the wax tohaze (spew) and the solvents to flash off (evaporate).Polish thoroughly by hand using clean, soft, lint-freecotton cheesecloth or terry cloth towels. Always use tworags for wax buffing. The first rag is used to remove thebulk of the wax. The second rag is used for finalpolishing. Avoid using fibrous paper products becausethey can scratch the surface and remove the waxrelease layer. Do not use a machine buffer for polishing,as it may burn through the waxed surface and leavebare areas. Allow each coat of release wax to drysufficiently. Refer to the manufacturer’s instructions fordetails.

Apply the remaining coats as described above. To helpavoid leaving unwaxed areas, begin and end each coatat a different place on the mold. Always wait for hazingbefore buffing, and always wait between coats. After thefinal coat has dried sufficiently, hand wipe the entiresurface with cheesecloth to remove any dust and dirt.

3. ADDITIONAL RELEASE PROTECTION—To furtherensure successful release from a master or plug, a film-forming material that creates a physical barrier can beused in addition to the six coats of wax release. PolyVinyl Alcohol (PVA) is a water/alcohol solution of water-soluble, film-forming materials. PVA is particularlyrecommended as an additional release agent on newmolds, and when molds are resurfaced, repaired orsanded, and buffed. Since it is water-soluble, it is notrecommended as a release film for gel coats or resinsthat contain water or emit water during cure. The PVAfilm does impart some degree of surface roughness tothe molded article, so some post-molding sanding maybe required to meet cosmetic requirements. Upon partremoval, the PVA should readily dissolve and wash fromthe molding with water. If the PVA adheres to the moldrather than the part, the film was probably too thin.

Upon completing the release wax procedure, apply twocoats of a non-silicone paste wax such as Ceara, Partall#2, Oscar’s 600 or TR108. The non-silicone paste waxwill help prevent fish eyes and allow the PVA to flowmore smoothly.



Page 1 of 4

POLYESTER TOOLING: Applying Release WaxCopyright 2008

ADDITIONAL RELEASE PROTECTION continued:

Best spray results are obtained with as fine a spray aspossible. Use high air pressure (80 to 100 psi) and lowPVA fluid flow. Normal spraying distance is 12 to 20inches. It is essential to apply several thin coats of PVA,and then follow with a ‘heavier’ wet coat to a filmthickness of approximately two to four mils. One gallonwill cover approximately 400 square feet. Drying time is15 to 30 minutes (depending on the temperature,

humidity, air movement and film thickness). Do not applytooling gel coat over wet PVA. When dry, the PVA filmshould be tack-free, very smooth and glossy. The spraygun should be cleaned with water, and then flushed withsolvent to remove the residual water. When using PVA,refer to the table on ‘Troubleshooting PVA Application’on the preceding page for suggestions.

4. TROUBLESHOOTING

Troubleshooting PVA Application

Observation Suggestion

1. Air bubbles in the PVA film .................................. Air pressure too low, use at least 80 psi dynamic at

the gun.

2. Film solution runs ................................................ Film sprayed on too wet and too thick.

3. Dull spots in the film caused by PVA overspray .. Spray dried PVA film with water to cause re-wetting

and flow out.

4. Entire film is dull and hazy, grainy looking .......... Film not thick enough, film not sprayed to a “wet”

coat.

5. Surface on part is rough and dull ........................ See problems above in 3. and 4.

6. Film won’t wet out evenly or fish eyes form ........ Contaminated surface. Do not use release wax that

contains silicone.

7. PVA etch (a dull, textured pattern on both mold

and part surface) ................................................. PVA film too thin (dust coat).

8. Hard, white build-up accumulates on the mold ... Laminate too hot or PVA too thin.

9. Part sticking ......................................................... PVA film too thin.

10 PVA stays with the mold, not the part ................. PVA film too thin.



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POLYESTER TOOLING: Applying Release WaxCopyright 2008



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Page 4 of 4

POLYESTER TOOLING: Building a Mold


Part Eight, Chapter VCopyright 2008

In This Chapter1. Mold Design Considerations

2. Tooling Gel Coat

3. Barrier Coats in Tooling Applications

4. Skin Coat

5. Conventional Bulking Materials

6. OPTIMOLD®

II Low Profile Tooling Products

7. OptiPLUS®

Low Profile Tooling Products

8. Bracing

9. Framing

1. MOLD DESIGN CONSIDERATIONS—Molds areusually produced using the contact (open) moldingmethod. The mold fabrication process must be designed,scheduled, and executed within a controlled time frame.Gel coat is applied and allowed to cure. Subsequently,the laminate is applied and it bonds to the previouslycured gel coat. This bond is a secondary bond and asource of potential weakness. For this reason, the gelcoat or laminate should never be allowed to curecompletely before applying the next layer of material.

There are several options to consider in the design of amold laminate. A mold laminate can consist of as little astwo components. At the minimum, tooling gel coatserves as the surface layer and a bulk laminate servesas the structural panel. The tooling gel coat must providea surface that is hard and has a natural shine, and avery smooth, glossy surface. Isophthalic polyestertooling gel coats provide the highest gloss, but with amodest strength and heat distortion temperature (HDT).Vinyl ester gel coats provide the highest strength andHDT, but at a modest gloss. Review the DS-45 (945Series) Tooling Gel Coat Data Sheet for specificmaterial, equipment, and application information.

One method to achieve synergy within these layers is touse a surface layer of tooling gel coat, with thesubsequent layer a vinyl ester barrier coat applied in amethod similar to that used with the gel coat. This barrier

coat serves to strengthen the gel coat and to enhancesurface cosmetics. Review the DS-67B ArmorGuard

®

Vinyl Ester Black Barrier Coat Data Sheet for specificinformation.

The laminate reinforcement can be any reinforcing fiber.Chopped gun roving at 30 to 35 percent reinforcementprovides best cosmetics and overall results. Higherstrengths can be achieved using continuousreinforcement, but print-through and distortion will begreater. Chopped strand mat (CSM) contains a binderresin, which can lead to dimples on the gel coat surface.Typically, there is less binder on one side of the CSM.This side should be placed against the gel coat layer.For best cosmetics, any CSM splices in the part areashould employ tear joints at the CSM edges.

A skin coat laminate is used to avoid air entrapment nextto the gel coat that would lead to subsequent flaws in thegel coat layer. A skin laminate is generally a thin layer,from 0.030 to 0.090 inches, of chopped gun roving at 30weight percent reinforcement. This corresponds tobetween one and three ounces per square foot (300-900grams/square meter).

The bulk laminate is usually made with one of three resinmaterials: conventional isophthalic laminating resin,OPTIMOLD

®II (alumina trihydrate filled zero-shrink)

laminating resin, or OptiPLUS®

(unfilled zero-shrink)laminating resin. Refer to the subsequent sections foreach material.

Total mold thickness depends upon the size and shapeof the mold. A thickness of 1/4 inch for up to 10 linearfeet, with an extra 1/8 inch for each additional five linearfeet is a loose rule of thumb. Thickness can varyaccording to different shapes, sizes, and needs. Thestyle and type of framing, as well as the mechanical andphysical properties for the laminating materials, alsoinfluence the design thickness.

Structural considerations are addressed with bracingand framing. Bracing is an element that is integral to themold laminate. Large molds usually incorporate balsacore materials. A shaped stiffener element, like a hat, orblade, can also be incorporated. Framing is a structure



Page 1 of 12

POLYESTER TOOLING: Building a MoldCopyright 2008

MOLD DESIGN CONSIDERATIONS continued:that surrounds and supports the mold from the backside. Generally, steel is used for framing, althoughsometimes wood is used.

For contact (open) molding, the frame is a cradle thatsupports the mold laminate, distributing its weight ontoconcentrated load points (usually casters). For highpressure resin transfer molding, the frame is a structuralreinforcement for the laminate that defines the moldcavity.

Once the mold’s design and construction methodologyare selected, one or more small test panels should beproduced to demonstrate suitable process conditionsand application techniques. Performance of these testsprior to building molds is very prudent and leads to thehighest quality mold for the lowest cost.

2. TOOLING GEL COAT—Before using tooling gelcoat to fabricate molds, a gel coat sprayout test panelshould be prepared. The sprayout should be madeunder the same conditions as those that will be used inspraying the actual mold. After evaluation, the sprayoutshould be retained along with other data as part of themold’s historical record.

The first coat of the tooling gel coat is the most critical,as this will be the surface that defines the final surfacequality. If porosity is evident after the film is gelled, thecoat should be removed and the problem corrected.Once the film is clean, with no porosity, pits, or pinholes,the second coat can be applied. Some tool builders usedifferent colors for the first and second gel coat layers.The color contrast provides a visible indication of howmuch gel coat is being removed during finishing,maintenance, and repair operations.

To produce a quality sprayout, first apply mold releasewax to a clean glass plate. A common size is 12 inchesby 12 inches. Then, using the same equipment, as wellas the same lot of gel coat and catalyst, spray a properlycatalyzed film of gel coat using the same techniques asused on the production mold. Use a wet-film gauge toensure the gel coat is applied in a smoothly sprayedlayer at 18 ± 2 mils (450 ± 50 microns) wet. Once cured,the gel coat film should be laminated or backed withmasking tape for demolding. The gel coat surface shouldbe visually inspected for imperfections. Sanding thesurface and wiping with a contrasting dye will reveal anysurface and/or internal porosity.

If the sprayout panel looks satisfactory, use the samematerial lots, equipment and application techniques toproduce the mold. If the panel does not look satisfactory,spray adjustments should be made until a high qualitypanel is produced that is porosity-free with no surfaceimperfections.

When using Binks pressure pot spray equipment, the 66fluid orifice, 65 needle, and 63 PB air cap combinationprovides a material flow rate between 1.5 and 2.5pounds per minute. An air atomization pressure of 60 to75 psi (at the gun with the fan full open) utilizes 17 CFMof air and normally ensures excellent atomization of thegel coat. Material flow rates in excess of 2.5 pounds perminute can create sags, pinholing, porosity andexcessive orange peel. Airless equipment requires a gelcoat with suitable properties.

The tooling gel coat should be applied in two smoothlysprayed coats of 18 ± 2 wet mils for each cure. Eachcoat should be developed through 3 spray passes witheach pass at right angles to the previous pass. The firstcoat should be allowed to gel between coats and cureonly to the point where it will not alligator when thesecond coat is applied. Normally, this time period is 90minutes at 77ºF (25ºC) and 1.8 percent catalyst. Thesecond coat may be a different color and can act as awarning when the first coat has been sanded throughduring the mold’s service life.

Lamination should begin only after the second layer oftooling gel coat has cured for 60 to 90 minutes or up to athree hours. The time element is dependent upon roomtemperature, air movement, humidity, catalyst type, andconcentration. If the gel coat cures too completely, itmay shrink and pull away from the master. The gel coatshould be covered with at least a skin laminate on thesame day it is sprayed to avoid gel coat prerelease.Excessive delays can also result in dust or dirtaccumulation that can prevent proper laminate adhesion.

Spraying tooling gel coat at temperatures lower than77ºF (25ºC) can result in undercure that appears later asdistortion and/or dulling of the mold surface.

3. BARRIER COATS IN TOOLING APPLICATIONS—A vinyl ester barrier coat can be used as a print-blockerto provide a smoother gel coat surface. This translatesinto a mold that yields parts with improved cosmetics.The barrier coat’s black color also provides a visual aidto detecting air bubbles during skin coat lamination. For



Page 2 of 12


BARRIER COATS IN TOOLING APPLICATIONScontinued:best cosmetics, the barrier coat should be in addition totwo layers of tooling gel coat. The thickness of thetooling gel coat should be reduced to 30 mils when abarrier coat is used. The barrier coat could also be usedas a substitute for the second layer of tooling gel coat,but at a slight cosmetic penalty.

The barrier coat material is applied in the same manneras a gel coat to a thickness of 16 to 20 mils (400-500microns). This build-up should done in three passes,with each pass at a right angle to the previous pass.Refer to the DS-67B ArmorGuard

®Vinyl Ester Black

Barrier Coat data sheet for specific applicationinstructions. VE barrier coats like the ArmorGuard

®do

have some porosity and should not be used as amolding surface. The porosity is intrinsic to VE-basedbarrier coats and does not present a problem whenapplied behind a full layer of tooling gel coat. Qualitycontrol is performed with Luperox

®DDM-9. The ideal

catalyst level is 1.8 percent at 77ºF (25ºC), and shouldalways be between 1.2 percent and 2.5 percent forproper cure. This generally requires ambienttemperatures in the 70 to 95ºF (21 to 35ºC) range.Successful usage is possible at temperatures slightlyoutside this range, but at an increased risk of prereleaseor poor cure. Normally, the barrier coat film is ready forlamination within 60 to 90 minutes. This time interval isdependent upon material temperature, roomtemperature, humidity, air movement, and catalystconcentration.

OPTIMOLD® II Catalyst Correction

Catalyst %

by Volume

Catalyst %

by Weight

0.90 1.27

0.95 1.34

1.00 1.41

1.05 1.48

1.10 1.55

1.15 1.62

1.20 1.69

1.25 1.77

4. SKIN COAT—A chopped glass skin coat laminateusing unfilled tooling resin is strongly suggested forcomplex geometries. The STYPOL

®040-4339 is the

recommended isophthalic skin resin and the ArmorStar®

VSX is a higher performance, epoxy-modified polyesterskin resin. Use of a skin coat provides the bestopportunity to prevent air voids behind the gel coatsurface. The skin coat also provides good mechanicalproperties and impact resistance, both of which directlyimprove mold life.

Any defects in the skin coat, such as blisters, voids,contamination, and/or foreign objects will transferthrough to the gel coat surface. These imperfections willnot always be visible on a new mold, but can appear asthe mold is used in production. Mold repair of thesedefects is time-consuming and will detract from theoverall mold surface quality. Removing a skin coatdefect by grinding can result in scratches, nicks, orgouges on the underlying mold or pattern surface. It isoften more economical to start over than it is to repairgouges on a fiberglass master mold or production mold.Removing skin coat defects by grinding should not beentrusted to untrained and/or unskilled personnel withoutaccepting the risk of damage to high value assets.

In general, a skin coat should contain 28 to 32 percentchopped glass fiber by weight. The nominal thicknessshould fall in the range from 30 mils to 90 mils. Achopped glass skin coat at 1 ounce per square foot (osf)glass will measure about 30 mils, 1.5 osf will measureabout 45 mils, 2 osf will measure about 60 mils, and 3osf will measure about 90 mils. A laminate thicknessgauge should be used to verify that the correct thicknessis applied. An air-free skin coat is easier to apply thinlyrather than thickly. A thinner skin coat should be ± 5mils, while a thicker skin coat should be ± 10 mils.

Zero-shrink resins such as OPTIMOLD®

II or OptiPLUS®

should not be used as skin coat resins. These resinsrequire a sufficient mass to produce the exotherm heatneeded for shrinkage control. Proper rollout and removalof all air voids becomes very difficult at the thicknessesrequired for shrinkage control.

For molds that will experience thermal cycling or thermalshock, the glass content should be lower in the layeradjacent to the gel coat than it is in the rest of thelaminate. For the greatest durability, a glass veil with aweight of 25 to 50 grams per square meter should be



Page 3 of 12


SKIN COAT continued:brush laminated right against the gel coat. Glass contentshould be 10 to 15 percent by weight. Due to the thinnature for a veil layer, the catalyst level should be at thehigh end of the recommended range for good cure. Thisresin-rich veil layer should be followed by a more typical30 percent chopped glass skin coat. The low-fiber-content veil layer provides a transition from the highthermal expansion characteristics in the gel coat layer tothe much lower thermal expansion characteristics in thestructural laminate. This reduces the stresses imposedby the thermal cycle or shock between the gel coat andlaminate, thus extending mold life.

Woven or stitched cloth materials should not be used ina skin coat. The resin shrinkage usually results in weaveprint (print-through) that is visible on the final moldsurface. The severity of this weave print depends uponthe fiber architecture in the material. For example,woven roving has large bundles that undulate (move upand down) at bundle crossovers. This results in a largeresin-rich area as a bundle crosses under another. Theresin shrinkage at these points will easily telegraphthrough to the mold gel coat surface. This can be sopronounced that the difference between 18 osy (ounceper square yard) WR (woven roving) and 24 osy WR willbe discernible. This weave print may not be visible whenthe mold is first produced, but may appear as the moldexperiences production cycles.

5. CONVENTIONAL BULKING MATERIALS—Aconventional bulking material is a thixotropic laminatingresin with a high heat distortion temperature (HDT).Historically, an isophthalic polyester resin has been theindustry standard. This type, like most laminating resinshrinks when it cures. This shrinkage causes an overalldimensional change in the molding and cosmetic flawsknown as distortion and print-through. Distortion is thesurface waviness visible on the panel surface when lightis reflected off the gel coat surface. Print-through is moresevere and can mimic the architecture of the fiber formsused in the underlying laminate. Mark-off is a cosmeticdefect that can appear when something such as a pieceof steel framing presses against the laminate back side.

Shrinkage occurs because of two mechanisms: curingshrinkage and cooling shrinkage. The first mechanism,curing shrinkage, occurs in two stages: during cure(before demold) and during postcure (after demold).Curing shrinkage is due to a volume change in the resin

that accompanies the cure. This curing shrinkage isinevitable and it is best when all of it occurs prior todemolding from the master. When some portion of thecure occurs after demolding, the additional shrinkagecauses cosmetic flaws to appear on the surface. This iscommonly called postcure, but it is really distortion thatis caused by the additional shrinkage that occurs duringpostcure. The second mechanism, cooling shrinkage, isdue to thermal expansion (actually contraction) when thelaminate cools from its stress-free temperature. Thestress-free temperature is related to the temperature thatis seen by the laminate when the resin solidifies. Thegreater the difference between the stress-freetemperature and ambient temperature, the more coolingshrinkage occurs. Therefore, the cooling shrinkage canbe managed by minimizing the exotherm temperatureduring the laminate cure. Postcure shrinkage isminimized by achieving a complete cure and mayrequire elevated temperatures. Cooling shrinkage isminimized by lower exotherm temperatures and minimalexposure to elevated temperatures. As a result, theoptimum cure profile is very strongly dependent on thelaminate exotherm temperature and resin area weight.

Minimizing shrinkage provides the best cosmetics.Completing the cure prior to demolding provides themost stable cosmetics. For conventional bulkingmaterials, this is achieved by single-ply laminations, oneper day, with a resin that is specifically designed to curein a single ply. Due to the extended nature of thislamination sequence, the secondary bonding windowbecomes important for scheduling purposes. Usually, amold is started early on a Monday, and laminationproceeds throughout the week. When lamination pausesgreater than 24 hours, as over a weekend, it is best toenhance secondary bonding with thorough mechanicalabrasion in addition to normal surface deburring. Forbest cosmetics, the completed mold laminate is allowedto cure for an additional five to 10 days prior todemolding. A new mold should always be demoldedprior to any elevated temperature postcure.

The most common single ply lamination is 45 mils (1.5ounces per square foot or 450 grams per square meter)at 30 weight percent reinforcement. Exothermtemperatures will run 5 to 15ºF (-15 to -9ºC) aboveambient, and are seldom tolerated as high as 140ºF(60ºC). Slight concessions in cosmetic quality occurwhen single-ply laminations are applied twice per day



Page 4 of 12


CONVENTIONAL BULKING MATERIALS continued:(such as morning and evening). Additional concessionsin cosmetic quality occur when double-ply laminationsare applied. These concessions are worse forlaminations closer to the gel coat surface.

Skin coat resins like STYPOL®

040-4339 or ArmorStar®

VSX are designed for single-ply lamination. Optimumcosmetics for double-ply or thicker laminations mayrequire a slightly different resin such as STYPOL

®040-

2989 isophthalic polyester tooling resin, which isdesigned to cure in thicker laminates. Refer to therespective product data sheets for more specificinformation.

6. OPTIMOLD®

II LOW PROFILE TOOLINGPRODUCTS—OPTIMOLD

®II resin is a two-component,

low profile resin system that incorporates aluminatrihydrate (ATH) filler. The two resin components areSTYPOL

®040-8060 and STYPOL

®040-8070. When

mixed, the OPTIMOLD®

II resin is a pre-promoted,thixotropic, shrinkage-controlled laminating resin.OPTIMOLD

®II is used to produce molds with

outstanding cosmetic quality and significant time andlabor savings. Laminate thickness can be added quicklywithout surface distortion. This surface quality isachieved via minimal resin shrinkage during the cureprocess. The minimal resin shrinkage provides a moldwith dimensions nearly identical to the master model.Unlike conventional isophthalic tooling resins, thecosmetic quality is very stable over the life of the mold.The OPTIMOLD

®II resins cure at room temperature with

a high-dimer MEKP initiator such as Arkema MEKP-925,Luperox

®DHD-9, or Chemtura HP 90.

The advantages of OPTIMOLD®

II are:

• Excellent cosmetic stability due to controlled-shrinkage technology

• Faster mold building than with conventionalisophthalic tooling resin

• Fire retardant characteristics due to the ATHfiller

• Good mechanical properties• Pre-promoted in pre-weighed packages

When using OPTIMOLD®

II to laminate molds, attentionto process details is a key element for success.OPTIMOLD

®II products are very sensitive to plant

airflow, cooling conditions, erratic operating conditionsand inconsistencies in application. Best results are

obtained by using OPTIMOLD®

II in a controlledenvironment with near ideal process conditions.

OPTIMOLD®

II is packaged in a short-filled, open-headdrum with a companion pail. This allows the mix to beprepared in the original container. The drum contains255 pounds of STYPOL

®040-8060. Each companion

pail contains 45 pounds of STYPOL®

040-8070. One pailof 040-8070 is added to the drum and mixed, followed by200 pounds of ATH filler (four 50 pound bags) for a 500pound batch at the proper mix ratio. For smaller batches,the mix ratio by weight is 40 parts ATH filler added to thepre-mixture of nine parts 040-8070 and 51 parts 040-8060. Recommended fillers are either R. J. Marshall A-208 or J. M. Huber SB-432.

Mixing the filler into the resin requires agitation with alarge paddle mixer. High shear mixing is not required nordesired. Overmixing increases the tendency to sag. Thefiller should be added slowly under gentle agitation.Avoid mixing air into the batch by using the least amountof turbulence possible. After the filler appears to bemixed in, the sides of the container should be scrapedclear of dry filler. Mixing should continue for 30 minutesto allow small particles of filler to completely wet. Toprevent filler settling, the mixture should be kept undergentle agitation until it is completely used. The mixtureshould be used within five days. After five days,extended gel times and loss of shrinkage control mayresult. It is best to use the entire batch on the same dayit is mixed.

A bung hole mixer will not adequately mix in the filler,resulting in clumps of unmixed (dry) filler on the mold. Airbubbling should never be used for mixing. It is noteffective and only serves as a potential for water or oilcontamination. Use of the mix prior to complete fillerwetting can result in localized, soft, filler-rich areas in thelaminate. If the material is allowed to sit without properagitation, the filler will settle to the bottom and be verydifficult to redisperse.

Laminating with OPTIMOLD®

II should be performed attemperatures between 75ºF (24ºC) and 90ºF (32ºC).Successful application is possible at temperaturesoutside of this range, but will require specificadjustments in laminate thickness and catalyst level tokeep exotherm temperatures within specification.Temperatures of all materials and process items shouldbe between 75ºF (24ºC) and 90ºF (32ºC). This includes



Page 5 of 12


OPTIMOLD®

II LOW PROFILE TOOLING PRODUCTScontinued:the master mold, the resin and the glass roving, inaddition to the ambient room temperature. Whentemperatures are outside this range, the likelihood ofpoor cure, excessive shrinkage or laminate expansionand the resultant substandard cosmetic quality isincreased. Prior to building each mold, small testlaminates should be prepared to demonstrate suitableprocess conditions and application techniques.

A chopped-glass skin coat using unfilled, tooling resin ishighly suggested for complex geometries. STYPOL

®

040-4339 is the recommended isophthalic skin resin.ArmorStar

®VSX is a higher performance, epoxy-

modified polyester skin resin. Use of a skin coat resultsin a modest compromise in surface cosmetic quality andstability, but provides the best opportunity to prevent airvoids behind the gel coat surface. The skin coat alsoprovides improved mechanical properties and impactresistance.

For OPTIMOLD®

II tooling resins, glass contents shouldbe between 22 percent and 28 percent by weight. Theideal glass content is 25 percent by weight. Lower glasscontents will result in excessive exotherm temperaturesand could cause expansion of the laminate. Higher glasscontents will result in lower exotherm temperatures andmay cause poor cure or excessive shrinkage. Therecommended glass rovings are Vetrotex #292, OCF357D, and PPG Hybon 6700.

Nominal uniform laminate thickness of 3/16 inch perlamination is recommended. The laminate thickness andcatalyst level can be adjusted for variations in ambienttemperature. The laminate thickness can range from 170to 220 mils. Obtaining a laminate exotherm temperaturebetween 110ºF (43ºC) and 140ºF (60ºC) producesoptimum results.

OPTIMOLD®

II quality control testing is performed usingSyrgis MEKP-925 initiator. Chemical equivalents, suchas Luperox

®DHD-9 or Chemtura HP 90, can also be

used. Cumene Hydroperoxide (CHP) and MEKP blendsare not recommended. Consult a CCP representative forother specific initiator recommendations. Under idealconditions at 77ºF (25ºC), use MEKP-925 at 1.5 percentbased on resin mix weight. For colder temperatures, asmuch as 1.75 percent can be used. For warmertemperatures, as little as 1.25 percent can be used.

Initiator levels slightly outside the range of 1.25 percentto 1.75 percent may be necessary at the temperatureextremes, but this can lead to substandard results and isnot recommended.

A standard resin pump with a catalyst slave pumpprovides catalyst adjustments based upon volume, notweight. Since the OPTIMOLD

®II is filled with ATH, and

ATH is non-reactive, the true catalyst ratio (by weight) isdifferent from the volume ratio marked on the equipment.The preceding table provides a cross reference betweenthe catalyst percentage by volume and the true catalystpercentage by weight for the OPTIMOLD

®II system.

If the laminate has turned uniformly white within 60minutes of catalyzation, it is most likely properly cured. Ifthe laminate is amber in color, or spotty white and notuniform, it is most likely poorly cured. Reconstructionshould be performed under more ideal conditions.Avoiding the need for reconstruction is bestaccomplished by building test laminates prior to full-scale mold building activities.

Most chopper guns configured for filled resins can beused to spray OPTIMOLD

®II resins. Standard

laminating equipment may require specific adjustmentsto ensure proper application. An increased spraypressure and/or larger tip orifice size may be requireddue to the viscous nature of an ATH-filled resin.

When using fluid impingement equipment, refer to themanufacturer’s recommendations for filled systems. Theglass content should be demonstrated by measuringprior to building a test laminate. The test laminate is thenused to verify catalyst level and laminate thickness. Moldbuilding should commence only after a test laminate issuccessfully produced.

OPTIMOLD®

II lamination begins with a mist coating ofresin on the working area. For the first lamination againstthe gel coat, apply 40 mils of gun chop in the work zone.This ‘air release’ layer should be rolled to eliminate all airat or near the gel coat surface. Once rolled and beforegellation, another 130 to 170 mils of gun chop is appliedto the work zone. This second layer is then rolled forconsolidation. A slow-motion rolling approach with a lighttouch helps to consolidate the material and helps toavoid just pushing the material around. Neighboringwork zones should then be covered in a similar manner,maintaining a ‘wet edge’ between work zones. A typicalwork zone ranges from 25 to 100 square feet, depending



Page 6 of 12


OPTIMOLD®

II LOW PROFILE TOOLING PRODUCTScontinued:upon the number of laminators and ambient temperatureconditions. This nominal 190 mil-thick lamination isallowed to gel and cure, which should occurapproximately 30 to 60 minutes from application to eachwork zone. The laminate should exotherm to 110ºF(43ºC) to 140ºF (60ºC) and should turn uniformly tan-white at approximately 75 minutes. Times in excess of90 minutes would suggest a reduced or poor cure, andsubsequent warpage and postcuring of the mold mayoccur. An infrared thermometer should be used tomonitor laminate exotherm, both for the test laminatesand the mold laminates.

Additional OPTIMOLD®

II laminations are applied untilthe design mold thickness is achieved. Each laminationcan begin once the mold temperature returns to nearambient temperature (comfortable to touch). Subsequentlaminations do not require the 40 mil-thick air-releaselayer, although applying material in two layers doesfacilitate rolling. The entire 190 mil-laminate thicknesscan be applied after the mist coating of resin for eachsubsequent lamination.

For best results, the entire OPTIMOLD®

II mold laminateshould be applied on the same workday. Spottyinterlaminar adhesion may result if one lamination isallowed to cure too completely. When delays arerequired, the STYPOL

®040-4353 Adhesion Promoter

should be used to achieve a good secondary bond.From the time properly catalyzed 040-4353 is applied,the secondary bonding window is six hours. Thismaterial is sprayed on the previous lamination in a thin,continuous film, one to four mils in thickness. Typically, itis sprayed similarly to paint or PVA, with fairly lowdelivery and low atomizing pressure. Refer to theSTYPOL

®040-4353 datasheet for specific spray

recommendations.

7. OPTIPLUS®

LOW PROFILE TOOLING PRODUCTS—OptiPLUS

®resins are used to produce molds with

outstanding cosmetic quality. This surface quality isachieved with minimal resin shrinkage during the cureprocess. Unlike conventional isophthalic tooling resins,the cosmetic quality is very stable over the life of themold. The OptiPLUS

®resins are pre-promoted,

thixotropic, shrinkage-controlled laminating resins thatdo not require the addition of fillers or additives. TheOptiPLUS

®resins cure at room temperature with

conventional MEKP initiators.

The advantages of OptiPLUS®

are:

• Excellent cosmetic stability due to controlledshrinkage technology

• Faster mold building than conventionalisophthalic tooling resin

• Lower weight molds than OPTIMOLD®

II (ATH-filled) tooling resin

• Excellent mechanical properties

When using OptiPLUS®

to laminate molds, attention toprocess details is a key element for success. OptiPLUS

®

products are very sensitive to plant airflow, coolingconditions, erratic operating conditions andinconsistencies in application. Best results are obtainedby using OptiPLUS

®in a controlled environment with

near-ideal process conditions.

Laminating with OptiPLUS®

should be performed attemperatures between 75ºF (24ºC) and 90ºF (32ºC).Successful application is possible at temperatures aslow as 60ºF (15ºC) or as high as 100ºF (54ºC), but willrequire specific adjustments in laminate thickness andcatalyst level to keep exotherm temperatures withinspecification. Temperatures of all materials and processitems should be between 75ºF (24ºC) and 90ºF (32ºC).This includes the master mold, the resin and the glassroving, in addition to the ambient room temperature.Temperatures outside this range are not recommendeddue to the high likelihood for poor cure, excessiveshrinkage, or laminate expansion and the resultantsubstandard cosmetic quality. Prior to building eachmold, small test laminates should be prepared todemonstrate suitable process conditions and applicationtechniques.

A chopped-glass skin coat using unfilled, isophthalictooling resin or ArmorStar

®VSX is highly suggested for

complex geometries. This results in a modestcompromise in surface cosmetic quality, but provides thebest opportunity to avoid air voids behind the gel coatsurface.

For OptiPLUS®

tooling resins, glass contents should bebetween 35 percent and 40 percent by weight. The idealglass content is 38 percent by weight. Lower glasscontents will result in excessive exotherm temperaturesand could cause expansion of the laminate. Higher glasscontents will result in lower exotherm temperatures and



Page 7 of 12


OPTIPLUS®

LOW PROFILE TOOLING PRODUCTScontinued:may cause poor cure or excessive shrinkage. Uniformlaminate thickness of 0.15 inches per lamination isrecommended. The laminate thickness and catalyst levelcan be adjusted for variations in ambient temperature.Obtaining a laminate exotherm temperature between130ºF (54ºC) to 160ºF (71ºC) produces optimum results.

OptiPLUS®

quality control testing is performed usingSyrgis MEKP-9 initiator. Chemical equivalents, such asLuperox

®DDM-9, can also be used. Under ideal

conditions at 77ºF (25ºC), use MEKP-9 at 1.5 percentbased on resin weight. For colder temperatures, asmuch as 2 percent can be used. For warmertemperatures, as little as 1.2 percent can be used.Initiator levels outside the range of 1.2 to 2 percent canlead to substandard results. High dimer peroxideinitiators, such as Syrgis MEKP-925, Chemtura HP 90,or Luperox

®L-50, can be used, but will provide longer

gel times. Cumene Hydroperoxide (CHP) and MEKPblends may also be used if the CHP is less than 35percent of the blend. Suitable cure should always betested. Consult a CCP representative for other specificinitiator recommendations.

If the laminate has turned uniformly white within 60minutes of catalyzation, it is most likely properly cured. Ifthe laminate is amber in color, or spotty white and notuniform, it is most likely poorly cured. Reconstructionshould be performed under more ideal conditions.Avoiding the need for reconstruction is bestaccomplished by building test laminates prior to full-scale mold building activities. Heat can also be added tospots to complete to cure.

Most laminating spray equipment can be used to sprayOptiPLUS

®resins. The equipment may require specific

adjustments to ensure proper glass contents. Twostrands of glass roving, reduced spray pressure, and/orreduced tip orifice size may be required. For fluidimpingement equipment, an orifice of 0.040-inch with a40 to 50 degree fan pattern at 40 psi is suggested. Theglass content should be demonstrated by testing prior tobuilding a test laminate. The test laminate is used toverify catalyst level and laminate thickness. Moldbuilding should commence only after a test laminate issuccessfully produced.

Mold laminate construction begins with a mist coating of

resin on the working area. For the first lamination againstthe gel coat, apply 0.040 inch of gun chop in the workzone. This air release layer should be rolled to eliminateall air at or near the gel coat surface. Once rolled andbefore gelation, another 0.11 inch of gun chop is appliedto the work zone. This second layer is then rolled forconsolidation. A slow-motion rolling approach with a lighttouch helps to consolidate the material and helps toavoid just pushing the material around. Neighboringwork zones should then be covered in a similar manner,maintaining a ‘wet edge’ between work zones. A typicalwork zone ranges from 25 to 100 square feet, dependingupon the number of laminators and ambient temperatureconditions. This 0.15 inch thick lamination is allowed togel and cure, which should occur at approximately 30 to60 minutes from application to each work zone. Thelaminate should exotherm to 130ºF (54ºC) to 160ºF(71ºC), and should turn uniformly tan-white atapproximately 75 minutes. Times in excess of 90minutes would suggest a reduced or poor cure, andsubsequent warpage and postcuring of the mold mayoccur. An infrared thermometer should be used tomonitor laminate exotherm, both for the test laminatesand the mold laminates.

Additional OptiPLUS®

laminates are applied until thedesign mold thickness is achieved. Each lamination canbegin once the mold temperature returns to nearambient temperature. Subsequent laminations do notrequire the 0.04 inch thick ‘air release’ layer. The entire0.15 inch laminate thickness is applied after the mistcoating of resin.

8. BRACING—A mold reinforcing element, bracing is acontinuation of the mold skin laminate. For contact(open) molding, bracing is used to react all of themolding forces, including those resulting from thedemolding event. Modest thickness increases result inlarge increases in bending stiffness, and therefore,robustness. Sandwich construction using a core materialsuch as balsa or plywood, is the simplest form ofbracing. Sandwich construction provides the addedbenefit of preventing damage to the mold surface frombackside impacts. Shaped stiffener elements can alsobe formed over foam, cardboard or wood patternmaterials. The most common shapes are hat stiffenersand vertical blade stiffeners. When contact moldsdevelop cracks, the best solution is usually to addbracing in the local areas. Bracing with laminate



Page 8 of 12


BRACING continued:materials and structural cores does not introducethermal stresses near as large as those possible withsteel framing.

9. FRAMING—A mold reinforcing element that isoutside the mold skin, framing falls into two differentcategories. For high pressure molding, framing must beused to react molding forces. These high pressureprocesses include conventional RTM and sometimesSMC. For low pressure molding, framing primarily servesas a cradle to distribute the mold weight ontoconcentrated load points such as casters. The framealso provides a means of grabbing the mold for liftingand transport operations without introducing loads atconcentrated points that can lead to laminate fracture.

Most mold frames are made from mild steel tubing. Thetubing may be square or round with a wall thickness ofapproximately 60 to 120 mils. Wood can also be usedand usually takes the form of deep-section bladestiffeners that are cut from plywood and entirelyencapsulated by the mold laminate. When wood is notencapsulated with laminate, moisture variations causethe wood to swell and contract, and should be avoidedfor all but small or temporary molds.

The differences in thermal expansion between a steelframe and an FRP mold skin are very significant. Aparameter known as the linear coefficient of thermalexpansion (CTE) is used to quantify a material’sresponse to a temperature change. For laminatedcomposites, there are three distinct coefficients.AlphaXX is the coefficient in the panel x direction,alphaYY is the coefficient in the panel y direction, andalphaZZ is the coefficient in the panel z thicknessdirection. The coefficient is defined as the change in unitlength for a unit change in temperature at a giventemperature. The thermal expansion coefficient for a gelcoat or unreinforced resin is between 31 to 55 micro-inches per inch per degree Fahrenheit, while a choppedglass laminate is between 11 to 18 micro-inches per inchper degree Fahrenheit in the laminate plane. Forcomparison, this laminate CTE is similar to aluminum,which is 13 micro-inches per inch per degree Fahrenheit.Steel, on the other hand, ranges from 5.5 to 9.5 micro-inches per inch per degree Fahrenheit.

Now, consider a temperature change from 70ºF (21ºC)to 0ºF (-40ºC). A 20-foot long piece of steel will contract

(20 foot long)*(12 inches per foot)*(7.5E-6 averageinches per inch per degrees Fahrenheit)*(70ºF [21ºC]temp change) = 0.126 inches (525 microstrain). As alaminate, that same 20-foot span will contract (20 footlong)*(12 inches per foot)*(14.5E-6 average inches perinch per degrees Fahrenheit)*(70ºF [21ºC] temp change)= 0.244 inches (1015 microstrain). The fiberglass panelcontracts 1.94 times as much as the steel structure.Structurally tying the two materials together and forcingthem to become the same length makes for big thermalstresses. Adding more steel simply compounds theproblem.

When thermal stresses are developed rapidly due to arapid change in temperature, one material can reach itsnew dimension much more quickly than the other. Withinthe same material, the same thing can happen atdifferent spots, depending on exactly how quickly itchanges temperature, and where. This is a rate-dependent, worst-case type thermal stress known asthermal shock.

To minimize thermal shock effects, the steel frame mustbe designed to expand and contract, at a rate that isdifferent from the mold laminate, without forcing the moldskin to crack. Therefore, the cradle and the moldlaminate must not be structurally coupled. This is bestdone by leaving a gap between the steel frame and themold laminate, and bridging this gap with a low-stiffnesstie made from a single piece of two osf chopped strandmat and a resin with a low inherent shrinkage. This isoften a production resin such as a DCPD (which has alow inherent shrinkage) that will cure in a thin laminate.Isophthalic tooling resin can also be used, but at ahigher cost and with higher shrinkage. Zero shrink resinslike OPTIMOLD

®II and OptiPLUS

™should never be

used as a frame tie resin because they will not cureproperly at the desired tie laminate thickness.

The contact mold frame is usually fabricated on thelaminated mold once the design mold thickness hasbeen applied and cured. Sections of tubing are cut andbent to fit while maintaining a gap between the tubingand the mold skin. Thick cardboard or crushable foam(two to four pounds per cubic feet urethane or PVC) isgood to use for a spacer. Either material is soft and cancrush without marking the mold gel coat surface. Oncepositioned, the pipe sections are welded together into asingle unit, and usually fitted with casters and provisionsfor lifting. One advantage to the OPTIMOLD

®II system



Page 9 of 12


FRAMING continued:when welding is the flame retardancy provided by theATH filler. For unfilled systems, careful attention whilewelding is important to avoid accidentally setting themold on fire.

When laminating the ties between the frame and themold skin, exercise care to avoid saturating the offsetspacers with resin, which will harden and defeat thespacers’ purpose. Once the ties are cured, the spacersshould be pulled out to prevent the future possibility ofmark-off.

Spacing between frame elements depends on the tubingsize and the thickness of the mold laminate. Small moldsless than 20 feet long will commonly use a laminatethickness of 1/2 inch and a tubing diameter from 1.25inches upwards of two inches. Frame spacing is set toprovide an unsupported panel length of 12 to 15 inches.For larger molds, two-inch by four-inch or largerrectangular tubing is used, oriented with the longerdirection perpendicular to the mold laminate. Sandwichconstruction with one-inch balsa core will commonlyseparate two 3/8 inch thick skins. For this heavier panelsection, the unsupported panel length may be as largeas 20 to 24 inches. These are ‘loose’ rules of thumb andshould not be construed as better than any frame designthat is tried and tested true.

Frame spacing and laminate thickness must alsoconsider the mechanical and physical properties of themold materials. For instance, the OPTIMOLD

®II system

utilizes lower glass loadings and a high filler content thatproduces a heavier mold skin with lower mechanicalproperties than a conventional isophthalic toolingsystem. The frame spacing must be smaller and themold skin must be thicker because of these features.

The frame must be rigid compared to the mold laminate.One way to evaluate frame rigidity is to jack up onecaster and see if the frame deforms. Another way is toposition the mold so that one caster is hanging over theedge of a loading dock. If it droops down noticeably, theframe is not rigid and is probably not supporting the moldproperly. If the frame is not rigid, picking up the mold cancause it to bend and twist, increasing the chance formold cracks to occur during normal handling and demoldoperations.

Wherever a steel frame is in contact with a moldlaminate, a mark-off may appear on the mold gel coatsurface. This mark-off may merely witness the contact,or it may lead to gel coat cracking due to point loading.Regardless, steel frame contact should be avoided forlow-pressure molding applications.

For high-pressure molding applications, a steel framemust contribute to reacting the molding forces. Any gapsbetween the steel frame and the mold skin are oftenfilled with a high-compression strength syntactic puttyafter the frame is constructed. For this reason,rectangular tubing is used instead of round tubing. Theframe is then structurally tied to the mold skin bylaminating with a heavy material such as woven rovingstitched to mat.

When steel framing is structurally coupled to a moldskin and used to react molding forces, normal thermalshocks experienced by moving molds from outside toinside and back in cold climates can result in extensivemold cracking. Additional steel framing does not improvethe situation. The only practical solution is to createconditions that slow to become close to outsidetemperature. At this point, the mold is moved into thespace and the outer door is closed. The inner door isopened somewhat, and the space is allowed to slowlycome back to the shop temperature, with the mold alsoslowly increasing temperature. The absolute worst-casescenario is to place a very cold mold directly under a big,forced-air or infrared heater running continuously.Unfortunately, these heaters are usually located near thedoor where cold molds are first brought inside and leftuntil the snow and ice melts from them.



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POLYESTER TOOLING: Mold Surface Distortion


Part Eight, Chapter VICopyright 2008

In This Chapter1. Types of Cosmetic Flaws

2. Causes

1. TYPES OF COSMETIC FLAWS—There are threetypes of cosmetic flaws that can develop on a gel coatsurface. The extent of these flaws can vary from minimaldistortion to major fiber print.

A. Distortion—Distortion is the waviness seen inlight reflected off the mold surface.

B. Print-through—Print-through is a pattern thatmi-mics the construction architecture of a fibrousreinforcement. Print-through can appear as a fiberbundle known as fiber print, or it can appear as theweave construction known as weave print.

C. Mark-off—Mark-off is a visible witness causedby differences in stiffness and hardness at theboundary from one material to another. Thisboundary is usually present in the mold or patternand transfers to the molded article. A commonexample is a plug constructed using a fiberglasslaminate and body filler. The body filler can be softerand can have a lower glass transition temperaturethan the fiberglass laminate. They also differ inthermal expansion and heat capacity characteristics.Both the heat from exotherm and the forces due toresin shrinkage apply stresses. These stresses aresupported and reacted differently by the differentregions. At the boundary between them, a mark-offcan result. Mark-off can also occur when a moldframe element is in contact with the back side of themold.

2. CAUSES—The gel coat surface often displays thesecosmetic flaws. The root causes, however, are not dueto any properties or characteristics of the gel coat layer.By itself, a gel coat film properly cured on a flat, polishedmaster will exhibit high gloss and visual smoothness.The gel coat matches the smoothness and gloss of the

mold surface. There is some loss of gloss andsmoothness in the molded part.

Even when resin is cast behind the gel coat film, theresulting surface will be very glossy, smooth, and freefrom these cosmetic defects. Cosmetic flaws are causedby how resin shrinkage is affected by different materials.These flaws will magnify when the gel coat is either thinor under-cured.

When a laminate is cured against the gel coat layer,cosmetic flaws will appear. Their severity is directlyrelated to the amount of resin shrinkage experiencedduring its cure. A resin that shrinks a lot will producecosmetic flaws to a greater extent than a resin thatshrinks less. These flaws are also influenced by thenature of the reinforcing fiber and the architecture of thefiber form in the underlying laminate.

Lack of shrinkage of a fiber doesn’t lead to cosmeticflaws. Instead, the flaws result when the fiber resists theresin’s shrinkage. Different fibers resist resin shrinkageto different degrees according to the fiber’s transversestiffness. Transverse to the fiber axis, glass fiber has astiffness of about 10 msi (million pounds per squareinch). Resin has a stiffness of about 1/2 msi, which is afactor of 20 less than glass. As the resin shrinks andtries to squeeze the glass fiber, the glass offers 20 timesmore resistance to being squeezed than the resin candeliver. This results in the image of the fiber being visibleon the gel coat surface because the resin-rich areasshrink away from the gel coat surface, while the fiber-rich areas resist shrinkage away from the gel coatsurface.

Carbon, graphite, and polymer fibers achieve a highstiffness in the axial direction due to molecularorientation imparted during the fiber manufacturingprocess. As a result, their transverse stiffness is low andcan be 1/2 to 2 msi. The lower the fiber transversestiffness, the less impact the fiber has on cosmetic flawsbecause it can’t prevent the resin from shrinking.Consequently, polymer fiber print blockers provide bettercosmetics than glass fiber veils.



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POLYESTER TOOLING: Mold Surface DistortionCopyright 2008

CAUSES continued:In a textile construction such as woven roving, thebundle weave (overlaps and underlaps) result in resinpockets that alternate with fiber bundles. Theunrestrained shrinkage in the resin pocket contrastsmarkedly with the restrained shrink-age in the fiberbundle, causing the weave print to appear on thesurface. Thus, the architecture of the fiber form has adistinct impact on cosmetics.

Resin shrinkage, fiber transverse stiffness and thearchitecture of the fiber form are the root causes ofcosmetic flaws. For a given fiber and form, such aschopped glass, cosmetic flaws vary in their severityaccording to resin shrinkage. Most resin shrinkageoccurs during the molding process referred to as thecuring operation. Any additional curing that occurs afterdemolding is called postcure. Postcure results inadditional shrinkage, and this postcure shrinkage causescosmetic flaws to develop.

Normal room temperature does not provide enoughenergy to completely cure an unsaturated polyesterresin. At some point in the cure, the cross-link densitybecomes high enough that the curing reaction stalls.Further curing requires temperatures that are closer tothe resin’s glass transition temperature. This furthercuring pushes the resin’s glass transition temperaturecloser to its maximum, resulting in a complete cure.Once the cure is complete, no additional cure shrinkagewill occur, and the cosmetic quality will stabilize. Usually,the final stages of curing occur when the moldexperiences exotherm heat during production of the firstfew parts.

Instead of allowing the postcure to occur when the moldis exposed to the exotherm heat generated by partsduring production, a new mold can be subjected to aspecial postcure operation. The postcure temperatureshould be chosen to be 20ºF (-6ºC) above the expectedproduction exotherm temperatures, or the expectedmaximum glass transition temperature for the gel coatand resin used to manufacture the mold, whichever isless. Four hours at temperature is generally sufficient tocomplete the cure and achieve the maximum glasstransition temperature. Isophthalic tooling gel coats havea maximum glass transition temperature of 200 to 210ºF(93 to 99ºC), while vinyl ester gel coats have a maximumof 250 to 260ºF (121 to 127ºC).

Any elevated temperature postcure should always beaccomplished with the mold in the free standingcondition, supported to prevent warping due to its ownweight. If a mold is postcured at elevated temperatureswhile it is still on the master, differences in thermalexpansion due to geometry will cause mark-off to appearin various places on the gel coat surface, on both themaster and the mold. For best cure results, any elevatedtemperature postcure operation should be scheduledwithin three days of the initial cure.

Wet sanding and buffing will remove cosmetic flaws thatdevelop on a mold surface due to cure and postcure.This should sensibly be performed only after the moldhas reached its final cure state. Once the cure iscomplete, no cure-related shrinkage will occurregardless of the temperature a mold experiences.

If the mold temperature is near or above its glasstransition temperature, however, the mold materials willsoften and can acquire a mark-off due to stressescaused by the shrinkage in a production part. If a partcontains woven roving, the weave print on a part cantransfer to the mold surface when the moldingtemperatures are near or above the mold’s glasstransition temperature. If the part is made with a zero-shrink resin, the part does not put shrinkage stresses onthe mold surface, and minor excursions above the moldglass transition temperature do not cause print totransfer from the part to the mold surface.

In summary:

• Molds will develop cosmetic flaws due to resinshrink-age during cure and postcure.

• The cosmetic flaws can be sanded out, but mayreturn if the mold is not yet fully cured.

• Parts made with conventional unsaturatedpolyester resin can print or distort a fully curedmold if the exotherm temperatures approach orexceed the mold glass transition temperature.

• Low profile resins will produce less severecosmetic flaws because these systems shrinknegligibly compared to conventional unsaturatedpolyester resin.

• Distortion (sometimes called orange peel) onlyappears on a gel coat surface when there is alaminate behind the gel coat. It is caused whena fiber’s transverse stiffness is great enough toresist the resin shrinkage. Distortion is not



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CAUSES /Summary continued:caused by the gel coat’s backside roughnessbecause a smooth draw-down of tooling gel coatdevelops the same degree of distortion as asprayed film that features back side orange peel.

• A gel coat film that is sprayed or drawn down(smooth surface) will not show distortion if thereis no laminate behind it or if there is onlyunreinforced resin behind it.

• If a tooling gel coat has a maximum glasstransition temperature of 212ºF (100ºC),postcuring the mold above this temperature willnot improve its distortion resistance.

• A ‘harder’ tooling gel coat does not resistdistortion any better. It may polish to a highergloss, but will exhibit a greater tendency tocrack.



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POLYESTER TOOLING: Mold Break-In Procedures


Part Eight, Chapter VIICopyright 2008


2. Conventional Mold Release Waxes

3. Semi-Permanent Mold Release Systems

4. Poly Vinyl Alcohol (PVA)

1. INTRODUCTION—A proper conditioning or break-inprocedure maximizes the mold’s value by preventingpart sticking, promoting gloss retention, and lesseningfiber print-through. Once the break-in procedure iscomplete, the mold is considered seasoned and can betreated with normal mold maintenance procedures.

Any mold can, at any point in its life, becomepermanently bonded to a production part. Inadequatelyreapplication of the mold release system is the mostcommon reason for part sticking. Porosity in the mold gelcoat surface is the second most common reason forsticking. The porosity allows the part to mechanicallyattach to the mold. This usually occurs after a mold hasbeen sanded and buffed because these operations canexpose subsurface porosity.

Gel coat surface porosity and micro-porosity are thereasons that a new mold has a higher likelihood ofsticking than a seasoned mold. Porosity that is visibleessentially guarantees part sticking. Micro-porosity,which takes at least 60x magnification to see, can beaddressed by the proper usage of a mold sealer. Mostmolds have some degree of micro-porosity. During thebreak-in procedure, mold release gradually fills moldsurface porosity, bonding permanently in place. This is agradual process that takes several production cycles.Once complete, the mold is considered seasoned.

A new mold, or a mold that has been sanded and buffed,should be inspected for porosity and micro-porositybefore determining the appropriate break-in procedure. Itmay be necessary to repair the porosity beforeproceeding. When-ever porosity is visible, the use of aPoly Vinyl Alcohol (PVA) film-forming barrier should be

used on the first few parts. If porosity is found on a newmold, the mold fabrication history data should bereviewed. In particular, the gel coat spray-out paneldescribed in Part Four, Chapter II, Section 11.3, GelCoat Application should be re-examined. The cause ofthe porosity should be determined, and procedures toavoid porosity should be implemented in future mold-making activities.

There are a number of approaches to mold break-in. Thefirst, ‘wax it and go,’ is not recommended for bestresults. Even though it works much of the time, the costsof failure are too great. In most instances, sealing andwaxing the mold is adequate. Best results are realizedby also applying a gel coat layer as a ‘blow coat’ (alsoknown as ‘strip coat’ or ‘peel coat’). To maximizechances for successful break-in, particularly on a porousmold surface, a film-forming barrier should be used onthe first few parts, but this imparts some texture on themolded part surface.

The three categories of release systems are:

• Conventional Mold Release Waxes• Semi-Permanent Mold Release Systems• Poly Vinyl Alcohol (PVA)

2. CONVENTIONAL MOLD RELEASE WAXES—Longused in the industry, mold waxes contain carnauba asthe release agent. The carnauba must bond to the moldsurface and be driven down into the mold pores.Carnauba is the hardest and most expensive of waxes inthe wax family. In pure form, it is very hard. The meltingpoint of carnauba is 183 to 187ºF (84 to 86ºC), whereasthe melting point of paraffin (sometimes used as arelease wax) is 117 to 150ºF (47 to 66ºC). Typically,mold release waxes contain a mix of carnauba, paraffin,and silicone (very few release waxes are silicone-free).The carnauba serves as the release agent, the paraffinsoftens the carnauba, and the silicone serves as alubricant so the carnauba/ paraffin can be easily wipedon and off. The chemical makeup and proportioning ofthe carnauba, paraffin, silicone, and solvent content isproprietary and varies not only by manufacturer, butwithin each manufacturer’s line of products. A sealer



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POLYESTER TOOLING: Mold Break-In ProceduresCopyright 2008

CONVENTIONAL MOLD RELEASE WAXEScontinued:glaze should always be used to close mold pores andseal new or reconditioned molds before applyingconventional paste wax.

3. SEMI-PERMANENT MOLD RELEASE SYSTEMS—Usually wiped onto the mold surface, these leave acured resinous film bonded to the mold surface. This filmserves as the barrier for release. A semi-permanentmold release should not be poured onto the moldsurface and subsequently wiped with a rag. This resultsin an overthick polymer film that leaves a visible mark-offat the puddle edge. It may be necessary to polish themold surface to remove this type of mark-off. Semi-permanent mold release systems should always be usedwith a compatible surface sealer. On porous moldsurfaces, a compatible surface primer should also beused. Surface primers generally produce a much thickerfilm that is chemically bonded to the mold surface.Primers should always be applied sparingly. Primersgenerally have no release properties and must alwaysbe followed with first, a sealer, then the release layers.Semi-permanent release system manufacturers claimmany more releases can be completed between updateevents. A secondary advantage is the ability to tailor therelease system to the type of release motion. Releasemotion describes the physical motion of the two surfacesinvolved in the release event. For perpendicular release,the surfaces move apart in a purely perpendicularfashion. For parallel release, the surfaces move apartwith some component of dragging between the two. This

release motion occurs on parts that have a deep draftand benefits from more ‘slippage’ in the release systemthan does a purely perpendicular release.

High slip release systems are microscopically thicker,which allows for some amount of release film erosion.The high-slip film’s greater thickness provides acorresponding decrease in finished part gloss. Incontrast, a semi-permanent release film that produces ahigh gloss is thinner and microscopically smoother andwears more quickly on deep-drafted parts. Semi-permanent mold release systems seem to cause morefish eyes and pre-releases than waxes, particularly onthe first pull, and are not recommended when buildingmolds and masters. As always, read and follow thesemi-permanent release manufacturer’s surfacepreparation and usage instructions.

4. POLY VINYL ALCOHOL (PVA) is a film-formingbarrier. Refer to Part Eight Polyester Tooling, ChapterIV, Applying Release Wax. When applied correctly, PVAforms a physical barrier between the mold and the part.A barrier film is only good for one release event and willhave to be applied for each part. It should be sprayed onrather than brushed or wiped. The PVA film will have anorange peel texture. This texture will transfer to the part,so some part rework may be required to meet cosmeticrequirements.

The following seasoning procedure should be followedon new molds and whenever a mold surface has beensanded and buffed:



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SEASONING PROCEDURE

1. Wash the mold surface with a mild detergent solution such as dish soap and water. Allow the surface to dry thoroughly. Inspect

the mold surface for porosity and micro-porosity. Apply a mold primer/sealer. Follow the specific recommendations from the

release system manufacturer. When using conventional paste wax, two coats of a sealer-glaze should be machine buffed, in

opposite directions.

2. Apply the mold release system. Allow each coat to cure. Follow the specific recommendations from the release system

manufacturer. When using conventional paste wax, six coats are generally sufficient.

3. Spray a blow coat with a hot pot. This is preferred over slave pumps or catalyst injection, where uneven catalyzation is possible.

It is best to spray tooling gel coat catalyzed at the high end of the recommended catalyst range, at the high end of the wet-film

thickness range. For large molds, divide the area into work zones and work on one section at a time.

4. Strip the blow coat from the mold when it reaches the ‘firm gel’ stage. Do not let the blow coat cure without peeling it from the

mold. If there is no sticking, proceed with the following step (5). In case of sticking, the mold must be repaired and completely

prepared again.

5. Update the mold release system after the blow coat has been stripped. Follow the specific recommendations from the release

system manufacturer. When using conventional paste wax, two coats are generally sufficient.

6. Spray production gel coat with a hot pot. This is preferred over slave pumps or catalyst injection, where uneven catalyzation is

possible. Laminate the first production part. If the first part pulls adequately, update the mold release system. Follow the specific

recommendations from the release system manufacturer. When using conventional paste wax, two coats are generally

sufficient. If the part does not pull adequately, the mold must be repaired and completely prepared again.

7. Build three more production parts. After each part, update the mold release system. Follow the specific recommendations from

the release system manufacturer. When using conventional paste wax, one coat is generally sufficient after each part.

8. Build two production parts without updating the mold release system. After the second part is pulled, update the mold release

system. Follow the specific recommendations from the release system manufacturer. When using conventional paste wax, one

coat is generally sufficient.

9. Evaluate the release performance for the second pull in the preceding step. If the part pulls adequately on the second pull,

gradually increase the number of parts built between update events. The number of parts between updating can vary from one

to as many as 10 or more. The exact number depends on a variety of factors such as part geometry, solvent content in the gel

coat layer, the gel time of the gel coat, exotherm heat generated in the laminate, the degree of cure of the gel coat and

laminate, etc.

10. Once the release system update interval is known, begin normal mold maintenance procedure. Monitor the mold for ease of

pulling and dullness or haze. It is important to update the mold release system before a part sticks, but maximum mold life is

obtained by updating the release system at the first sign of dullness or haze. When using conventional paste wax, a non-

abrasive build-up remover and a machine buffer will remove the haze without breaking the surface seal. Two additional coats of

paste wax are generally sufficient to return the mold to serviceable condition.



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POLYESTER TOOLING: Mold Maintenance


Part Eight, Chapter VIIICopyright 2008

In This Chapter1. Protocol

2. Procedure

1. PROTOCOL—Properly constructed contactlaminated molds will produce many thousands of parts.Maximum value, however, will only be achieved if a goodmold maintenance protocol is followed. Lack of disciplinewhen executing a mold maintenance protocol alwaysresults in excessive costs for reworking, repairing, orrefinishing the mold. A preventive maintenance programis essential to ensure long mold life. The preventiveapproach is proactive and prevents damage fromoccurring to a mold surface. Updating a mold releasesystem after a part sticks is not considered a preventive,proactive approach and always leads to lower qualityand higher costs.

2. PROCEDURE—The mold maintenance area shouldbe completely enclosed and away from the productionarea. In order to control dust and overspray, thereshould be isolated stalls for grinding and gel coating.

Residue that forms on a mold surface is not what wasonce referred to as wax build-up. True wax build-up ismore correctly described as wax leave-on because thisbuild-up occurs when excess wax is not buffed off.Residue build-up is due to styrene (polystyrene) whichhas come from the production gel coat and whichadheres to the mold usually for one of these reasons:

• Paste wax leave-on or overapplication of thesemi-permanent release agent.

• Inadequate cure of the release system• Pulling parts too soon. The more green a part is

when pulled, the more susceptible it is forstyrene (polystyrene) to remain on the mold.

• Micro-porosity in a mold surface that has notbeen adequately sealed

If the mold is used beyond the proper mold releaseupdate interval, the residue will accumulate more rapidly.

Eventually, the build-up will require sanding to remove.

Colors appear to haze a mold more (or sooner) than awhite or off-white gel coat. This phenomenon has beenobserved with all gel coats and is not limited to generictypes or those from various manufacturers. Colors differin formulation because of solids and pigmentation. Anydark-colored pigments will tend to be more visible thanlight-colored pigments when trapped in the polystyrenebuild-up. The hazing is usually noticed because colorsare used as a striping accent (side by side) next to thewhite or off-white base coat. Hazing in and of itself is notdamaging to the mold, although its removal can reducemold life. Premature hazing can occur when anundercured gel coat film is followed by hot laminate thatis too green when pulled.

When using conventional paste wax, light residue andhaze can be removed by machine polishing the moldwith a buildup remover such as TR-502 Wax Build-UpRemover. This will not break the surface seal in therelease system. Performing this cleaning every three tofive pulls for deep draft parts and every six to nine pullsfor shallow draft parts eliminates most problems withhaze. Two coats of fresh paste wax will return the moldto its serviceable condition. When using a semi-permanent release system, follow the specific cleaningrecommendations from the manufacturer.

If the mold is very hazy and has some textured build-up,a coarser compound should be used followed by a washwith a mild detergent solution and a rinse with coldwater. Some compounds, if not removed by a detergentwash, will cause sticking by preventing the mold releasesystem from bonding to the mold surface. Compoundingwill break the surface seal in the release system, so thecomplete mold seasoning procedure should beperformed as described in Part Eight, Chapter VII MoldBreakin Procedures.

If the mold has considerable residue build-up, it will haveto be removed by scrubbing with a commercial stripper.When using conventional paste wax, toluene, methylethyl ketone, or ethyl acetate can be used as a stripper.When using a semi-permanent release system, follow



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POLYESTER TOOLING: Mold MaintenanceCopyright 2008

PROCEDURE continued:the specific stripping recommendations from themanufacturer. These stripper materials can beflammable and potential health hazards. Refer to theappropriate MSDS sheets for all safety precautions. Ingeneral, always wear gloves and safety glasses, andensure the area is well-ventilated. Do not use styrene forcleaning molds because it initiates and promotes theprocess of polystyrene build-up on the mold surface.

For molds that have been extensively neglected,removing the polystyrene residue will require dry andwet sanding, followed by compounding and buffing. Thiserodes a significant portion of the tooling gel coat layer,thus greatly reducing the life of the mold. The entiremold seasoning procedure will return the mold to itsserviceable condition, albeit minus some of the gel coatlayer.



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POLYESTER TOOLING: Mold MaintenanceCopyright 2008



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POLYESTER TOOLING: Mold Resurfacing


Part Eight, Chapter IXCopyright 2008


2. Gel Coat Cracks

3. Laminate Cracks

4. Steps to Resurface a Mold

1. INTRODUCTION—Mold resurfacing is an expensiveproposition. Resurfacing a mold involves applying a newlayer of tooling gel coat. Since the gel coat is sprayedonto the existing mold surface, the new surface featuresan orange peel texture. This texture must be sandedsmooth in much the same way that a master pattern issanded and polished. When the resurfaced area is large,the labor required to finish the mold can cost more thanbuilding a new mold from the polished master.

Small portions of a mold can be resurfaced fairlyeconomically. If there are cracks in the tooling gel coator laminate, they can easily reappear on the resurfacedmold. Any cracks must first be completely removed bygrinding.

2. GEL COAT CRACKS—Remove only as muchmaterial as is necessary to remove the crack. The spacecan be filled with a putty made from tooling gel coat andfumed silica. The crack should be overfilled, allowed tocure, and post-cured with a heat lamp or hot air gun. Ifthis is done before the surface is sanded smooth, thecure shrinkage won’t cause the repair to sink below thesurrounding surface.

3. LAMINATE CRACKS—Each layer that contains acrack should be ground away several inches either sideof the crack, with the edges tapered back to theundisturbed laminate thickness. Then, additionallaminate bracing should be applied on the mold backside in the damaged area. This is imperative becausethe mold was not strong enough and stiff enough toresist the cracks initially. Once the laminate is properlybraced on the back side, the front side laminate isreplaced.

4. STEPS TO RESURFACE A MOLD—The followingprocedure describes the steps to resurface a mold oncethe substrate is repaired and braced to prevent futurecracks:

A. The surface should be sanded with a verycoarse grit to help remove any release agent andalso to provide a point for mechanical adhesion. Usesandpaper between 60 and 100 grit.

B. Blow off the mold with compressed air.

C. Wash the mold with acetone (or equivalent)until there are no smear streaks left on the mold.Use several clean cloths so that wax and dust areremoved (review the precautions for solvents).

D. Set up the gel coat spray equipment toproduce as fine a spray as possible. Typically, lowerflow rates and higher atomizing pressure willproduce less orange peel on the new gel coatsurface.

E. Prepare the tooling gel coat as follows (ifspraying with airless or air-assist airless equipmentuse 945GA104 or 945YA058 only; if spraying withpressure pot, any CCP tooling gel coat can beused):

1) For multi-coating, the first coat (andsecondary coats if used) must not containwax or surfacing agent solutions. Usepatching thinner to reduce the gel coatviscosity and improve leveling. Catalyze at1.2 to two percent dependent ontemperature. Spray the gel coat in threepasses to a wet film thickness of 14 ± 2 mils.Allow this coat to cure to typical layup time(approximately 90 minutes at 77ºF (25ºC)).Follow with the top coat.

2) For the top coat, combine 75 parts toolinggel coat and 25 parts PATCHAID

®. Catalyze

at 1.2 to two percent depending upontemperature. Spray in 3 passes to a wet filmthickness of 14 ± 2 mils. Allow this to cure atleast overnight. Postcure with a hot air gun



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POLYESTER TOOLING: Mold ResurfacingCopyright 2008

Prepare the tooling gel coat continued:or heat lamp to ensure that all shrinkage iscomplete prior to finishing.

F. Orange peel should be minimal enough suchthat no coarser than 320 grit sandpaper can be usedto eliminate the orange peel. Finish by wet sandingup through 1000 to 1500 grit sandpaper. Compoundand polish using a machine buffer. Wash the moldpatch with a mild detergent solution such as dishsoap and water. This mold should now be seasonedas if it were a new mold.



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POLYESTER TOOLING: Mold ResurfacingCopyright 2008



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POLYESTER TOOLING: Mold Storage


Part Eight, Chapter XCopyright 2008

In This Chapter1. Preferred Storage Environment

2. Condition of the Mold

3. Outdoor Storage

1. PREFERRED STORAGE ENVIRONMENT—Mostmolds will eventually be stored for use at a later time. Aswith a classic car, the best storage conditions result inthe least wear and tear during the storage period. For amold, temperature and humidity climate control is anunnecessary expense, but shelter from the outdoorelements is essential to maintaining quality duringstorage. Uncovered, outdoor storage may be the leastexpensive from a capital standpoint, but always resultsin greater rework and mold maintenance costs.

2. CONDITION OF THE MOLD—Any dirt and dust thataccumulates on the gel coat surface can cause surfacescratches and abrasion that leads to loss of gloss ifremoved while dry. Best results when removing dirt andgrime are obtained using a mild detergent solution suchas dish soap and water. The solution lifts the abrasivedirt particles off the surface, preventing scratching andloss of gloss.

Rainwater should never be allowed to stand in aconcave mold feature. Standing water provides abreeding ground for mosquitoes, but worse, leads toblistering of the tooling gel coat layer. Gel coat blisteringrequires complete re-placement of the gel coat layer inthe affected areas and can be more costly than buildinga new mold from a polished master. In addition, if thewater freezes, its expansion can cause the mold tofracture.

Direct sunlight will cause the gel coat surface to losegloss, develop chalk, and craze. Tooling gel coats areformulated for long-term gloss retention and releaseperformance, not resistance to ultraviolet radiation.Tooling gel coats based on vinyl ester chemistry areparticularly prone to chalking. Applying a gel coat layerand skin coat can provide some protection from theelements. If the laminate releases, however, liquid watercan accumulate between the gel/skin and the moldsurface, leading to blistering.

3. OUTDOOR STORAGE—If outdoor storage isunavoidable, best results are obtained by orienting themolds upside down on wooden pallets, covered with alight colored tarp above and open to the air below. Dirtand grime will accumulate on the mold surface andrequire removal with a mild detergent solution, butblistering and ultraviolet degradation will be largelyeliminated.

If the backside of the mold will be exposed to sunlightduring storage, a layer of white production gel coat willreflect the sun’s energy, lowering the temperatures itreaches in summertime. This layer should be applied tothe mold’s back-side just prior to installing its frame.After the frame ties are glassed, PVA can be sprayedover the entire construction to ensure good surface cure.

The ideal storage conditions for FRP molds are indoors,heated during periods of extreme cold, and covered witha sheet such as painter’s plastic to avoid dirt and grimeaccumulation.



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POLYESTER TOOLING: Mold StorageCopyright 2008



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POLYESTER TOOLING: Special Precautions


Part Eight, Chapter XICopyright 2008


2. Precautions

1. INTRODUCTION—There is an economic advantageto producing a quality long lasting mold that requires littleor no subsequent finishing. This requires strict qualitycontrol methods in the application of both tooling gelcoat and the mold laminate.

The approach to designing and building molds requires adifferent mind-set than the approach to buildingproduction parts. During production, certain short cutscan provide recurring savings. However, during moldfabrication, short cuts can provide recurring costsbecause mold flaws translate directly into part flaws oneach production part. Extra care and effort during moldfabrication reduces part re-work costs, providing arecurring savings. Many gel coat and laminating defectsresult from conditions that can easily be corrected.

2. PRECAUTIONS—Please note the following:

A. Do not use more than 2.4 percent catalyst inthe tooling gel coat. Excess catalyst can causeexcessive shrinkage of the gel coat. This leads topre-release from the master surface. For adequatecure, do not use less than 1.2 percent initiator.Disperse catalyst thoroughly in the gel coat. Poordistribution causes uneven cure, color variation andpremature release before layup. While mixing byhand, the material should be poured from onecontainer into another to facilitate top-to-bottomdispersion. Best results are obtained with a smallmixer attached to a variable speed pneumatic motor.Best cure is obtained when the ambient, materialand mold temperatures are between 70 and 90ºF(21 and 32ºC).

B. Tooling gel coat should not be left to cureovernight before at least a skin coat lamination isapplied. Excessive film cure results in a loss of tackand reduced bond quality between the gel coat and

laminate. In addition, the likelihood for prerelease isgreater.

C. Install oil and water traps on the air lineleading to the spray gun. These traps will removelint, rust, oil, other contaminants, and liquid water. Awater trap will not catch moisture in the form of watervapor. Therefore, the compressed air should be coolwhen it enters the water trap or else water vapor willpass right through the trap. This can be checked byrunning a test with an extra 50-foot hose and a toolthat consumes a lot of compressed air. A spray gunwill not show this fault because the spray gun isdesigned to atomize high molecular weight gel coatand will vaporize any water that has condensed inthe compressed air line. The tool should be run forabout as long as one would expect to be sprayingthe tooling gel coat. If liquid water sputters out thetool exhaust, the water trap is passing vapor that iscondensing in the hose or in the tool. Water in thegel coat film will cause problems and should beremoved with a compressed air cooler. Compressedair coolers are commercially available. A simple,homemade cooler can be fashioned from a 50-footcoil of 1/2 inch copper tubing that is spiraled to fitinside a plastic tub or drum filled with tap water.Gallon jugs of ice can provide additional coolingwhen placed in the water within the tubing spiral.

D. Proper spray technique is very important toprevent pinholes and porosity in the gel coat film.Use slow, even strokes, keeping the gun at rightangles to the surface. Trigger the spray gun at theend of each stroke to prevent build-up at overlaps.Begin applying gel coat near the booth exhaust inorder to avoid over-spray from air-drying on themaster. Air-dried overspray can cause pigmentseparation and form pinholes once the tooling gelcoat is applied. Pigment separation appears like awatermark on the cured gel coat surface. The gelcoat must be well atomized and each coat applied toa wet film thickness of 18 ± two mils in three passes.Subsequent passes should always be at right angles



Page 1 of 4

POLYESTER TOOLING: Special PrecautionsCopyright 2008

Proper spray technique continued:to the prior pass. Use conventional air atomizationwith a minimum of 60 psi dynamic (at the gun,trigger pulled wide open). Low atomizing pressurewill result in poor breakup and leave entrapped air(pinholes) in the sprayed film.

E. Do not use internal air atomization sprayequipment, catalyst injection or airless sprayequipment with standard tooling gel coat. Thesetypes of equipment often result in thick films andporosity. See DS-45 tooling data sheet for specialinstructions regarding gel coat application usingairless equipment.

F. Best results when spraying tooling gel coat areobtained by using a pressure pot. This preventscatalyzation problems due to surging in resin orcatalyst pumps, lack of calibration, and poor mixing.Avoid material delivery rates in excess of 2.5 poundsper minute because more than this is difficult toatomize.

G. Never add acetone or other solvents to toolinggel coat. A compatible patching thinner orPATCHAID

®can be used for repair activities.

PATCHAID®

contains a surfacing agent thatprevents air from inhibiting the cure. This surfacingagent can prevent a second layer from adhering. Formultiple cured coats, the patching thinner (withoutthe surfacing agent) is recommended.

H. Molds can develop stress cracks due tothermal shock. If molds are stored at coldtemperatures and then suddenly brought into awarm building, the rapid heat up can cause stressesthat lead to fracture in the gel coat.

I. Manufacturers of conventional paste wax claimindefinite shelf life as long as the solvents do notevaporate. Keep containers closed except to removethe wax. Do not apply paste wax using the ‘sockmethod.’ This involves tying the wax up into a ballwith sheeting. The sock allows solvent and oil topass through, but the waxes remain in the sock.

J. Semi-permanent mold releases have a shelflife and must be kept closed when not in use. Thesematerials are polymers that require humidity forproper cure. Low humidity conditions will extend thetime required for them to cure. Always follow thestorage and usage recommendations from the semi-permanent release system manufacturer.

K. Both conventional paste wax and semi-permanent mold release systems must bond to themold surface. A good bond requires a clean moldsurface. The residue from rubbing or polishingcompounds must be removed using a mild detergentsolution such as dish soap and water. If theseresidues are not removed prior to mold releaseapplication, the first pull may remove the releaseagent and the second part can stick.

L. Do not be afraid of silicones. Most mold waxescontain silicone, and nonsilicone types are theexception rather than the rule. Excess silicone canand will cause problems, such as fish eye andprerelease. The important thing is to make sure allexcess wax is polished from the tooling gel coatsurface. Fish eye and prerelease will be more of aproblem on fresh wax than on ensuing parts.

M. Do not use high-speed buffers (more than3,000 RPM). High-speed buffers cause excessiveheat and can lead to burning.



Page 2 of 4

POLYESTER TOOLING: Special PrecautionsCopyright 2008



Page 3 of 4







Page 4 of 4

THERMACLEAN® PRODUCTS


Part NineCopyright 2008

In This Section1. Introduction

2. Technology

3. Application

4. Waste Disposal

1. INTRODUCTION—Traditional cleaning solvents forequipment and tools in the composites and castingindustries have been acetone, methyl ethyl ketone, ethylacetate, methylene chloride, and toluene. Theseconventional solvents have been used for every aspectof tool and equipment cleaning as well as personnel skincontact cleaning. These solvents are volatile andflammable to varying degrees. Methylene chloride, whilenot flammable, is a known cancer causing agent. In thepast several years, the toxicological and environmentalrisk aspects of these cleaning products have causedfabricators to seek alternative cleaners. Desirablefeatures for such alternative cleaners are:

• Effective polymer solubility or loosening• Carrying ability of the cleaner• Low volatility• Low/no flammability• Reasonable cost• Ease of disposal• Reduced risk to employees, facility, or

environment.

Benefits derived through reduced fire insurance rateshave been further encouragement for alternatives. CCPmanufactures ThermaCLEAN

®, a line of replacement

cleaners which meet the above listed objectives andwhich provide CCP customers with a product supportsystem that addresses technology, application, andwaste disposal.

ThermaCLEAN®

products are effective industrialcleaners with lower environmental impact when used asreplacements to conventional, highly volatile solvents.These products are used in a variety of cleaning

applications within the composites, industrial, culturedmarble/cast polymers, and other industries.

2. TECHNOLOGY—The ThermaCLEAN®

product lineconsists of two basic technologies:

• Water-based products, including resinemulsifiers and wipe-down cleaners• High flash point, no HAP, low VOC emission,solvent-based products, including a variety ofspecialized gun flushes.

These products are cost effective when compared to lowflash point solvents because ThermaCLEAN

®products

have very slow evaporation loss rates. Further, thewater-based products can be diluted with up to 10 partsof water.

These products also significantly improve personnel andplant safety, since high flash point solvents greatlyreduce fire hazards, while low toxicity minimizesemployee health risks. ThermaCLEAN

®products are

non-hazardous for flammability and toxicity by EPA andDOT definitions.

3. APPLICATION—To assist customers with the use ofThermaCLEAN

®products, CCP provides a wide range

of application support. This support extends fromspecialized equipment which improves productivity, suchas CCP’s MARBLECLEAN

™machine, redi-SCRUB

machine, and its AQUACLEAN™

machine, to specializedapplication tips for product use, as well as technicalconsulting by the ThermaCLEAN

®support group.

4. WASTE DISPOSAL—Water-based products can bereused if the resin/filler precipitate is separated from thecleaner. Once spent, these product may be sewerable(with prior POTW approval) or disposed of through anappropriate waste disposal company. Solvent-basedThermaCLEAN

®products should only be disposed of

through an appropriate waste disposal company.Another disposal option is to work with your CCPrepresentative, who can introduce the Chemcare

®

national waste disposal program of Univar USA forThermaCLEAN

®products. Customers who chose the

Chemcare®

program are offered:



Page 1 of 4

THERMACLEAN®

PRODUCTSCopyright 2008

WASTE DISPOSAL continued:• Complete financial indemnification• National contract pricing• Preapproved waste profiles• Simplified account set-up• Instant technical assistance and regulatory

compliance support• Network with over 100 locations and 500

permitted vehicles

CCP customers who choose ThermaCLEAN®

productsnot only use the best environmental cleaners available,but gain access to CCP support and resources as well.

ThermaCLEAN®

products are well-demonstrated as theyhave been specifically developed in CCP’s researchlaboratories to clean a variety of gel coats and resins,including epoxy, urethanes, unsaturated polyesters, andvinyl esters.

Product data sheets describing the entireThermaCLEAN

®line are available on request through

CCP customer service or through CCP’s website atwww.ccponline.com.



Page 2 of 4

THERMACLEAN®




Page 3 of 4







Page 4 of 4

IMEDGE® PRODUCTS


Part Ten, Chapter ICopyright 2008


2. IMEDGE®

PCT100

3. IMEDGE®

PBT200

4. Conclusions

1. INTRODUCTION—CCP’s IMEDGE®

products arehigh performance In Mold cutting EDGE polymertechnologies that offer unique and revolutionaryalternatives to conventional FRP materials. TheIMEDGE

®technologies were developed to promote and

drive innovation in the FRP industry. The IMEDGE®

product line represents CCP’s commitment to be aleader in the industry through technology, sales, andtechnical and customer support. IMEDGE

®is a

technology platform from which new and innovativeproducts will be launched on a regular basis.

The initial product offerings in the IMEDGE®

product lineare

• IMEDGE®

PCT100—Polymer CoatingTechnology

• IMEDGE®

PBT200—Polymer BarrierTechnology

The benefits of each product are described below.

2. IMEDGE®

PCT100—IMEDGE®

PCT100 is a MACT-complaint coating that provides a visibly glossier, darkerand more richly colored surface than traditional gel coat.These cosmetic benefits of IMEDGE

®PCT100 are most

evident in dark colors. IMEDGE®

PCT100 colors havebeen measured more than 2 color units darker thanconventional MACT-compliant products when bothsystems are pigmented similarly. Fiberglass partsfabricators and their dealers are recognizing the “newlook” of parts built using the IMEDGE

®PCT100

technology and have called the appearance difference“remarkable.”

The deep, rich color and high gloss of the IMEDGE®

PCT100 coating system can easily be restored to itsinitial gloss and color when sanded and buffed for repairand finishing operations. Conventional MACT-compliantdark color gel coats get lighter in color when sanded andbuffed. The IMEDGE

®PCT100 shows less than one unit

total color change after sanding and buff back or morethan 75% less color change than currently availableMACT-complaint gel coat products. Gloss of theIMEDGE

®PCT100 is also restored with sanding and

buffing without the use of any additional finish materials.

Another benefit of IMEDGE®

PCT100 is its blushresistance or resistance to color change with waterexposure. The panel shown in Figure 10/I.1 illustratesthe blush resistance of the IMEDGE

®PCT100. Half of

the panel was fabricated with a competitive gel coat andhalf with IMEDGE

®PCT100. The center portion of the

panel was then exposed to boiling water for 100 hours.

Figure 10/1.1 - Blush Resistance.

The conventional gel coat blushed or lightened, while theIMEDGE

®PCT100 retained its original color. IMEDGE

®

PCT100 can now be considered for applications needingcolor retention with water exposure. Opportunities for anew, remarkable look include marine applications underthe water line and sanitary applications. IMEDGE

®

PCT100 is also being evaluated for pool and spaapplications



Page 1 of 6

IMEDGE®


IMEDGE®

PCT100 has excellent resistance to theeffects of weathering. Figure 10/I.2 shows a comparisonof IMEDGE

®PCT100 to a conventional gel coat

technology noted for its superior weatheringperformance. Both coatings were pigmented to a jetblack color. The figure shows gloss and total colorchange results for panels exposed to QUV-A, anaccelerated weathering test method.

Figure 10/1.2 - QUV -A Weathering.

QUV-A testing is typically run for 2,500 hours. Even thebest performing gel coats will typically fail (gloss <50) bythe end of this exposure. Less weathering resistantgrades will fail much earlier. The superior weatheringgrade gel coat performed as expected with good glossand color retention over a significant portion of theexposure. However, this gel coat eventually reached

IMEDGE®

PCT100 continued:gloss failure and chalked. For IMEDGE

®PCT100, the

exposure time had to be extended and, even at 3,500hours of exposure, the IMEDGE

®PCT100 did not reach

gloss failure. The IMEDGE®

PC100 did not chalk,showing almost no color change during the entireweathering exposure

In addition to the benefits described above, IMEDGE®

PCT100 also has excellent cracking resistance,particularly when used in conjunction with IMEDGE

®

PBT200. It is also resistant to porosity during application,has excellent scratch and wear resistance, and lowweight per gallon. IMEDGE

®PCT100 is applied using

the same equipment and techniques as conventional gelcoat.

3. IMEDGE®

PBT200—IMEDGE®

PBT200 is atoughened polymer barrier technology that has excellent

resistance to cracking. Exterior coating cracks lead tosignificant internal rework and warranty expense for FRPmanufacturers. The crack resistance of IMEDGE

®

PBT200 can be demonstrated by numerous tests,including elongation, flexure to first crack, and reverseimpact. Elongation as determined by a mandrel bendtest is shown in Figure 10/I.3. Elongation values of atypical isophthalic gel coat and vinyl ester barrier coatare shown for reference.

Material Elongation

Isophthalic Gel Coat 1.8

VE Barrier Coat 1.3

IMEDGE® PBT200 4.5

The elongation of IMEDGE®

PBT200 is more than twicethat of the isophthalic gel coat.

Figure 10/1.3 - Flexure to First Crack Test Schematic.

Figure 10/1.4 - Flexure to First Crack Test Schematic.



Page 2 of 6

IMEDGE®


Flexure to first audible crack is a modified version ofASTM D790 Flexural Properties of Unreinforced andReinforced Plastics and Electrical Insulating Materials. Aschematic of the test is shown in Figure 10/I.4. Thecoating side of the sample is in tension. Loading of thespecimen is stopped at the first audible crack. Resultsare generally expressed as toughness or the ability ofthe material to absorb mechanical energy until fracture.

Figure 10/1.5 - Flexure to First Crack Toughness

Flexure to first crack toughness for IMEDGE®

productsare shown in Figure 10/I.5. Several other results areshown as reference. These include a typical isophthalicgel coat, two applications of isophthalic gel coat,isophthalic gel coat backed by VE barrier, and theIMEDGE

®PCT/PBT system.

These results confirm that increasing the thickness ofthe gel coat decreased the toughness. This result isconsist with historical field results that thick gel coat ismore prone to cracking. Also, use of a VE barrier coatincreased toughness versus an isophthalic gel coat. Themost significant result is that the use of the IMEDGE

®

PCT/PBT system resulted in nearly twice the toughnessof the other systems.

In reverse impact testing, the impact is applied to thenon-coated side of the laminate. The test apparatus isshown in Figure 10/I.6.

Figure 10/1.6 - Impact Test Apparatus

After impact the samples are visually examined on thecoating side for cracking. Impact heights are varied untilpassing and failing heights are identified. The passingheight is the maximum impact height at which no cracksoccur. The failing height is the minimum impact height atwhich cracking begins. A major marine manufacturer isusing reverse impact testing to screen coatingsmaterials. This company believes that coatingperformance in the reverse impact test is a keyparameter in reducing the level of warranty claims forcracking.

Reverse impact results are shown in Figure 10/I.7.Samples in this testing consisted of the coating systemsbacked by 12 plies of 1.5 oz. CSM laminate constructedusing a typical DCPD blend laminating resin. Thesamples were impacted using a 4 pound weight. TheImpact Energy shown in Figure 10/I.7 is the product ofthe impact height and the impact weight. Results for atypical isophthalic gel coat, isophthalic gel coat backedby a VE barrier, and isophthalic gel coat backed by aVE/DCPD skin laminate are shown for reference. Use ofIMEDGE

®products more than doubled the impact

energy or drop height required to create cracking.

In addition to its toughness and crack resistance,IMEDGE

®PBT200 provides excellent water resistance

and blister protection. This can be seen in Figure 10/I.1.



Page 3 of 6

IMEDGE®


The panel shown in this photograph was constructedusing IMEDGE

®PBT200 behind both the competitive gel

coat and IMEDGE®

PCT100 coating. The entire water-exposed area of the panel is free of blisters and othereffects of water with the exception of the blushing of thecompetitive gel coat.

IMEDGE®

PBT200 also provides an excellent barrieragainst print and distortion. The rapid cure of theIMEDGE

®PBT200 allows it to provide this protection

while taking much less processing time thanconventional barrier coat products or skin laminatetechniques. In some nonstructural applications,IMEDGE

®PBT200 can also reduce the need for detailed

rolling typically done in the skin laminate. The IMEDGE®

PBT200 provides a tough barrier between air in thelaminate and the part surface.

IMEDGE®

PBT200 meets the United StatesEnvironmental Protection Agency emissionsrequirements for reinforced composites production.Some process modifications will be required to apply thisunique, new barrier technology but the application issimilar to a conventional barrier coats. A sprayapplication of 60 mils wet is recommended for thePBT200.

Figure 10/1.7 - Reverse Impact.

4. Conclusions—IMEDGE®

PCT100 and PBT200 areinnovative products developed to meet specific needs ofthe FRP industry. CCP customers who chooseIMEDGE

®products choose to be on the leading edge of

FRP technology and position themselves for furtherinnovations launched from the IMEDGE

®technology

platform.



Page 4 of 6

IMEDGE®




Page 5 of 6







Page 6 of 6

APPENDIX A: Quality Control Lab and Test Methods


Part Eleven, Chapter 1Copyright 2008

In This Chapter

1. Introduction

2. Basic Needs and Equipment

3. Basic Testing Methods and Equipment

4. Physical Testing

5. Sources of Equipment

1. INTRODUCTION—The fiberglass industry isconstantly changing. Parts are made at faster rates, witha demand for higher quality and better durability. Thereis less latitude for errors that can cause unsatisfactoryproducts and costly downtime. Everything must workproperly and be compatible.

Many companies in the fiberglass industry are setting uptheir own internal quality control (QC) labs to monitormaterials, to do in-house process monitoring, and toassure performance of final parts. Qualification for ISOcertification requires monitoring of materials andprocess.

A QC lab (or any laboratory) has one basic function: itcollects and reports factual information that should beused to make reasonable decisions. A QC lab cananswer the following questions:

• Is the material to be used really what thesupplier says it is?

• Does it meet in-house requirements forprocessing?

• Is consistent material (necessary for optimumproduction schedules and requirements) beingsupplied?

• Does a new vendor’s different material matchthe presently used product?

• Can production use the product?• Is production consistent?• What amount of material is actually used on

each part? Are parts consistent, not only inweight, but in quality?

• Is the process used in making the part cost-efficient?

• Does a specific change in production actuallybring about a cost or quality benefit?

• Are the products and parts compatible with eachother to produce the desired quality?

A QC lab can also perform several other functions:

• Evaluate new products, equipment, orprocesses

• Run safety testing• Coordinate samples to be sent out for testing—

product testing, environmental testing, oranalysis work

• Assume responsibility for regulatory activities(Sara III Reports)

A QC lab can also provide:

• Design, testing• Cost information on parts• Cost estimates on new parts

Before setting up a quality control lab, it is important foreach company to review its expectations and determinethe scope of its needs.

A single company’s needs will vary greatly (e.g., criticalaerospace applications versus non-critical parts), andone company’s needs will vary greatly from another. It isnot possible for CCP to provide a complete layout or listof equipment for each possible situation. Listed in thischapter, however, are basic equipment and generalcosts. Final choices are up to each fiberglassmanufacturer.

2. BASIC NEEDS AND EQUIPMENT—The mostrudimentary quality control lab needs a room that istemperature-controlled and that is equipped with goodlighting. Other requirements are a sink with hot and coldwater, electrical outlets for test apparatus, shelves, anda desk.

One of the primary functions of a QC lab is recordkeeping. Data must be collected, recorded, and put in aform that is usable and accessible for decision-making.



Page 1 of 19

APPENDIX A: Quality Control Lab and Test MethodsCopyright 2008

BASIC NEEDS AND EQUIPMENT continued:

The economical way of doing this is with pencil andpaper. Use of a computer with a spread sheet program,database, or statistical quality control program is a betterway to organize and review data.

A QC lab should have available a list of all raw materials,with approved suppliers, used in the company’s plants. Itshould have the phone numbers of not only the salespeople but the technical staff of suppliers. A list ofindustry organizations such as the ACMA and SPI-CI,with phone numbers, may also be helpful. Files ofMaterial Safety Data Sheets (MSDSes) from suppliersand certificates of analysis should be maintained. All ofthe test methods that the lab is to use must be readilyavailable.

The QC lab should have a system for reportinginformation. Simple forms can be used and should bearranged so that the characteristics and consistency of abatch can be seen at a glance.

When a material is logged into the lab, there are anumber of QC steps that should be done. The details ofthe actual test depend on what type of part will be madefrom the material, and what is required from it. Start withthe simplest tests and then move on to the morecomplicated. First steps must be taken before finalsteps. It is acceptable to pause anywhere along theprocess as long as steps are taken in order.

These steps will normally include:

A. Record the following information on a particularproduct or raw material when received:

• Code number• Batch number• Batch date• Date received• A part number if available• Specifications (if set up for a particular raw

material) should be listed with theirtolerances

• If a spec sheet comes with the material, itshould be compared to standardspecifications and the typical results ofprevious batches.

B. Visual Inspection—The simplest inspection isvisual and is oftentimes overlooked. This shouldconsist of:

• Examining containers as they are received.Are any damaged? Is there any swelling orbuckling? Are there any leaks?

• Opening the container and examining thematerial. Does it appear like the previousbatch? Is it roughly the same color, cloudy,clear, etc.? Are there any visible signs ofcontamination, water, etc.? NOTE: The colorof resins may vary from batch to batch. Ifthere seems to be a significant variation,check with the supplier. Results of thesevisual inspections should be written down.

• Mixing the container’s contents and visuallycomparing it to the inspection report’sreference to the unmixed appearance.NOTE: Some settling may be normal. It isimportant to be aware of materials that needto be mixed before use.

• Pulling a sample, putting it in a propercontainer and marking it with the codenumber, batch, batch date and datereceived. Save this for testing or futurereference for 90 days. NOTE: Polyestersshould be stored in opaque containers at73°F or below.

The following are also required for the precedingprocedures: clipboard, paper, paper cups,containers and a marker.

Before initiating a testing program, it is important toobtain a list of all the normal tests and proceduresused by the supplier to control the quality of theproduct.

Review the literature for test methods and decidewhich test procedure to use. The selected procedureshould be written up and filed in a notebook. A copyof the proposed procedure should be sent to thesupplier with a request for comments.

Any time a test is run, results should be recordedand compared to the standard and to previousbatches.

C. The following general methods andequipment used in testing catalysts may be used totest a variety of materials.



Page 2 of 19


The following general methods continued:

While a very small component, catalyst is a veryimportant one. There are only two basic tests thatcan be run with catalysts (unless the laboratory ishighly sophisticated). These tests are:

• Visual—Check the clarity of the product;look for any seeds, crystals or cloudiness inthe material. If found, contact the supplier atonce.

• Reactivity—Tests must be run to compare anew lot of catalyst to an old lot of catalyst inthe same resin or gel coat. For QC work tobe effective, tight controls are required foraccuracy. Run gel, cure, and peak.

Equipment needed for catalyst testing includes:

1) A water bath, accurate to within 1°F. Anexample of this type of bath is Blue MagniWhirl Model MW110A1.

2) A gel meter. CCP uses Sunshine gelmeters.

3) A balance accurate to 0.1 gram.4) A thermometer accurate to within 0.2°F.5) For a more permanent record of

temperature changes or time versustemperature, a strip chart recorder isrequired.

The equipment mentioned here is provided as anexample; other brands may be suitable.

Figure 11/1.A1 - Titration for acid value.

3. BASIC TESTING METHODS AND EQUIPMENT

A. Acid Number (Similar to ASTM D 465-59)—The acid number is the number of milligrams ofpotassium hydroxide (KOH) necessary to neutralizethe free acid end groups in one gram of sample.

This test is used on resins to determine how far thereaction has proceeded during cooking; it is alsoused for batch-to-batch consistency. The acidnumber will vary from resin to resin; it may be ashigh as 60 or as low as 3.

NOTE: Acid number can be calculated in either oftwo ways: On resin solids only (monomer factoredout), or on total solution (monomer not factored out).CCP acid numbers are based on resin solution.

1) Procedure:

a) Weigh 5.6 grams of resin into a 150 mlErlenmeyer flask (or other similar sizedcontainer).

b) Add about 20 ml of the following solventmix:

Toluene .......................33 grams

Xylene..........................33 grams

Ethanol

(denatured) .................

34 grams

Phenolphthalein ..........2 grams

c) Swirl and warm on a hot plate, ifnecessary, to dissolve the resin.

d) Titrate, using 0.1 normal KOH solutionuntil the resin solution holds a faint pinkcolor for 30 seconds (the color will tendto fade away).

e) The acid value (AV) = ml of KOHsolution used.

B. Barcol Hardness (similar to ASTM D 2583)—This test is used to determine the hardness of amaterial as it cures. It also can be used to comparethe hardness of different resins and the developmentof cure. A Barcol impressor measures the resistanceto penetration of a needlelike point on a scale ofzero to 100. It requires a mass of material to obtainan accurate reading.

Two different Barcol meters are used in the FRPindustry:



Page 3 of 19


1) Model 935 (softer materials), normally usedfor initial readings.

2) Model 934 (hard materials), normally usedfor ultimate cure or when 935 gives readingsof 75 or above.

Figure 11/1.A2 - Barcol meter..

Barber-Colman, manufacturer of the Barcolimpressor, is specific regarding instructions (andlimitations) for the proper use of the Barcolimpressor. Barber Coleman advises:

• For accurate readings, material should be atleast 1/32 inch (31 mils) thick.

Barcol Hardness (similar to ASTM D 2583)continued:

• The testing area should be smooth and freefrom mechanical damage.

• As a general rule, the number of readingstaken increases with the softness of thematerials being tested.

Barber-Colman recommends numbers of readingsfor the Model 934:

Hardness

Scale

(934)

Reading

Variance

Number of Readings

30 0.77 29

40 0.78 22

50 0.75 16

The recommended number of readings for the 934can serve as a starting point when using the 935meter.

Barcol readings taken on rough surfaces will varymore than readings taken on smooth surfaces.

Barcol hardness can be measured on productionparts as well as used in the QC lab on lab samples.In production the test is not applicable for gel coats.The gel coat film is too thin. The barcol meterpenetrates through the film and reads the hardnessof the material behind. Measurement of Barcolhardness for laminate cure can be an effective wayto judge cure development in production as thefabricator progress through the laminate build or fordetemining demold times.

Barcol hardness testing in the QC lab is describedbelow. This test method is not recommended forproduction gel coats, but is appropriate for resinsand tooling gel coats.

3) Procedure—Many times, this test is run atthe same time as the gel time test. Thesample size is increased to either 150 gramsor 200 grams and brought to 77°F andcatalyzed.

a) Calibrate Barcol impressor with testdiscs supplied.

b) Note the time of catalyzation.c) Weigh a specific weight of catalyzed

resin into an aluminum weighing dishand place on a nonheated, insulatedsurface in an area free from drafts.Remainder of sample is used for gel



Page 4 of 19


time test.d) After the sample has gelled, test sample

every five minutes with a pencil. If thepencil dents the resin, do not use Barcolimpressor. Note that time starts frommoment of catalyzation, and testnormally runs one hour, or until areading of 70 or 80 is reached on a 935Barcol.

e) If a pencil will not dent the resin, take areading with the 935 Barcol impressorby pressing needle assembly into theresin, noting the average of at leastthree readings. Make sure needleassembly is perpendicular to resinsurface.

f) Continue this procedure until 935 Barcolreaches 60 to 70. When this occurs, the934 may also be used.

g) Report time and readings. Needle mayfade toward zero. Make note if thisoccurs.

h) If any resin sticks to the needle, washneedle to prevent blockage. See thefollowing example:

Time

(min.)

935 934

Catalyzed

Gelled

0

15

20-25

30

35

40

45

50

55

60

--

--

--

5

15

50-60

70

80

80

80

--

--

--

--

--

0

0-5

15

20-30

40

C. ANSI (American National Standard for PlasticBathtub Units)—The purpose of this standard is toestablish generally acceptable quality for plasticbathtub units. It serves as a guide for producers,distributors, architects, engineers, contractors, homebuilders, code authorities, and users; to promoteunderstanding regarding materials, manufacture,and installation; to form a basis for fair competition;

and to provide a basis for identifying bathtub unitsthat conform to this standard. This standard and testprocedures deal with the acceptability of a plasticbathtub unit as a plumbing fixture. Building codesmay have additional requirements.

Figure 11/1.A3 - Boil tester.

This standard has a number of tests within it. All willnot be covered in detail (see the actual standard).Basically, the tests which must be run by anindependent lab are:

1) Workmanship and Finish—This test spellsout how many defects and blemishes areallowed after visual inspections, inking, andsanding.

2) Structural Integrity—This series states whattypes of loading and impact the drain fittings,sidewalls, and floor must withstand.

3) Water Resistance—This is the 100 hour boiltest (212°F [100ºC]). NOTE: Type Fourbathtub units (thermoplastics) are tested at180°F (82ºC); not in boiling water. The 100hour boil test requires a panel to be exposedto boiling water, normally for 100 hours. Thepanel is then visually inspected for colorchange, blisters, change in surface profile,cracks, and loss of visible gloss. Each item



Page 5 of 19


is rated on a scale of zero to 5, with zerobeing no change and five being extremechange approaching maximum possible.The ratings are somewhat subjective and acertain degree of change in each category(e.g., color, change, blisters, cracks, etc.) isallowed. Failure occurs when any one areais rated above 4 or when the total of all fiveareas is above 9. NOTE: The applicability ofthis test is to compare product to product.Field suitability has not been established. Ithas been used to rank materials under oneset of conditions, but passing or failure doesnot automatically imply that material is or isnot suitable for other types of applications.Suitability is determined by the user.

4) Color Fastness—This is a 200 hourweatherometer test.

5) Stain Resistance—The stain resistance to anumber of chemicals is tested.

6) Wear and Cleanability.7) Ignition Test.8) Cigarette Test—This test checks if the unit

can be ignited or irreversibly damaged by acigarette burn.

NOTE: Type Four units (thermoplastic faced)have a series of other test requirements; see thestandard for details.

D. Color—Polyester resins possess a color thatranges from water-clear to dark amber. This colorvaries with resin type and formulation. Resin color isnormally only important when the resin is used tomake water-clear castings and translucent sheeting.

NOTE: Additives like cobalt will affect the color.There are two color tests.

1) Gardner Color ASTM D 1544-74—This isthe normal test; a test tube of resin iscompared to known standards and is rangedfrom 1 (lightest) to 18 (darkest).

2) APHA Color (Hazen)—This test is used torank resin when the Gardner color isregistered at 1 or less. Again, a tube of resinis compared to known standards.

3) Spectrophotometer Measurements—A colorstandard must be established in order to run

a color test. Normally, a color standardshould be a gel-coated panel. The standardmay be developed by matching some otheritem such as vinyl, paint, etc. Once thematch is selected, three matched panelsshould be made up. Each panel should bepermanently marked on the back as‘Standard, Part Number ___, Color ___,Date ____.’ Each panel should be at leastthree inches by five inches in size andplaced in envelopes. One should go to thesupplier, and one is a working standard thatis used day-to-day. The third panel isretained as a master, stored in a cool, darkplace, and only used when the workingstandard is in question. This is the finalreference for color.

If accurate color consistency is required, themaster standard and working standard mustbe kept in the freezer when not in use. Colorstandards will change upon aging. Thatchange can be minimized by storingbetween 0°F and 32°F. In this case, afreezer is necessary.

NOTE: This freezer should not be used tostore peroxides or food.

The equipment for running color is:

1) Fiberglass or glass mold.2) Spray gun, one quart pressure pot, stem

cut off so a small bottle (eight ounce jar)can be inserted. (One and two are usedto prepare cured sprayouts for batchcolor comparisons.)

3) Light source—one of the following, inorder of effectiveness:a) North lightb) Fluorescent light (cool daylight

bulbs)c) A light boothd) Color instrument.

4) A consistent observer with no colorblindness for visual color comparison.

See Part Four, Chapter II.2 Color for further details.

E. Dielectric Strength, ASTM D 149

1) Specimena) Specimens are thin sheets or plates



Page 6 of 19


having parallel plane surfaces and of asize sufficient to prevent flashing over.Dielectric strength varies with thicknessand, therefore, specimen thickness mustbe reported.

b) Since temperature and humidity affectresults, it is necessary to condition eachtype of material as directed in thespecification for that material. The testfor dielectric strength must be run in theconditioning chamber or immediatelyafter removal of the specimen from thechamber.

2) Procedure—The specimen is placedbetween heavy cylindrical brass electrodeswhich in-crease in voltage during the test.There are two ways of running this test fordielectric strength:a) Short-Time Test: The voltage is

increased from zero to breakdown at auniform rate of 0.5 to 1.0 kv.sec. Theprecise rate of voltage rise is specifiedin governing material specifications.

b) Step-by-Step Test: The initial voltageapplied is 50 percent of breakdownvoltage shown by the short-time test. Itis increased at rates specified for eachtype of material and the breakdown levelnoted.

The term ‘breakdown’ used with thesetests means passage of sudden currentflow through the specimen and can beverified by instruments and visibledamage to the specimen.

3) Significance—This test is an indication ofthe electrical strength of a material as aninsulator. The dielectric strength of aninsulating material is the voltage gradient atwhich electric failure or breakdown occursas a continuous arc (the electrical propertyanalogous to tensile strength in mechanicalproperties). The dielectric strength ofmaterials varies greatly with severalconditions, such as humidity and geometry,and it is not possible to directly apply thestandard test values to field use unless allconditions, including specimen dimensions,

are the same. Because of this, the dielectricstrength test results are of relative ratherthan absolute value as a specification guide.

F. Fire Tests—The use, applicability, andstatements regarding fire test results must behandled with great care, as this whole area is in agreat state of flux due to federal regulations.Different regulatory bodies have differentrequirements for a material’s fire resistance. Themajor question to answer is: Does the fire resistancetest predict what happens in an actual fire? The

Fire Tests continued:

documented tests at this time are full-scale testswhich absolutely predict what will happen underactual fire conditions. Other currently available teststell only how materials burn under a single set ofconditions.

Listed on this and the following pages are commontests which have been used to rate the burningproperties of polyesters, but may or may not be CCPrecommendations. These tests are:

1) ASTM D 635—This test was designed tocompare the flammability characteristics ofdifferent materials, in controllingmanufacturing processes, or as a measureof deterioration or change in flammabilityrating prior to or during use. In the test, atleast ten specimens five inches in length by0.5 inches in width and thickness of thesample normally supplied (usually 1/8 inch)are marked one inch from each end. Thespecimens are held in position with thelongitudinal axis horizontal and thetransverse axis at 45 degrees to thehorizontal. The specimens are ignited for 30seconds with a Bunsen burner with theflame adjusted to a prescribed height. Therate of burning is calculated (inch perminute). This is not a very severe test anddoes not distinguish relative flammabilitycharacteristics between specimens whichhave good flame retardant properties. Atbest, it can only be utilized for roughscreening work.

2) HTL-15 Intermittent Flame Test—Theapparatus needed for conducting this test is



Page 7 of 19


quite simple. The test is much more severethan the test previously described becausethe specimen is suspended in a verticalposition and heat from the burner will becarried upward by convection along thelength of the specimen. In addition, thespecimen is ignited five times usingincreasingly longer ignition periods. Thesequence of ignition times and flame withwithdrawals follows:

Applications Ignition Time

(Seconds)

Burner

Withdrawn

(Seconds)

1 5 10

2 7 14

3 10 20

4 15 30

5 25 50

In rating a sample, five specimens eight by1/2 by 1/8 inches are burned. If the flame isextinguished within the period that theburner flame is withdrawn, the specimen haspassed the ignition test. Each of the five testignitions successfully passed is worth 20toward the rating for that specimen. Forexample, if a specimen successfully passesthe five ignitions and flame-off periods, it israted at 100, four ignitions rate at 80, and soon. An average is taken of the ratings for thefive specimens.

3) ASTM E 162—In this method, a radiant heatenergy source is used to supply heat to thesurface of a specimen being tested. It isbelieved that in using a radiant energysource rather than supplying heat by apropagating flame, more accurateobservations of the progress of the flame-front can be made. The heat source consistsof a vertical 12 by 18 inch panel in front ofwhich is placed an inclined six by 18 inchspecimen. The specimen is oriented in sucha manner that ignition occurs at the upperedge and the flame-front moves downward.

A factor derived from the rate of progress ofthe flame-front and another relating to therate of heat liberation by the material undertest are combined to provide a flame spreadindex. The amount of smoke evolved duringthe test can also be measured. It is pointedout in the ASTM Method that the method,although suitable for research anddevelopment for measuring surfaceflammability of materials, is not intended forrating materials for building code purposes.

Fire Tests continued:

4) ASTM E 84—This is a large scale test whichrequires a considerable amount of materialand is quite expensive to set up and run.Only a few test ‘tunnels’ used for this testare in actual use in the United States. Thepurpose is to determine the comparativeburning characteristics of the material beingtested by evaluating the flame spread overits surface, fuel contributed by itscombustion, and the density of smokedeveloped when exposed to a test furnace.Briefly, the specimen for combustion (afterprior conditioning) is fastened to the roof ofthe tunnel and ignited by means of a gasflame impinging on the surface of thespecimen. The gas flow is carefullyregulated. During the test, air is drawnthrough the tunnel at a constant rate. Smokedensity is measured by means of a lightsource and a photoelectric cell in thefurnace vent; fuel contributed is measuredby means of thermocouples placed near thevent end of the furnace. The furnace iscalibrated using red oak flooring andasbestos board as standards. Conditionsare adjusted so red oak spreads a flame thelength of the furnace in five and 1/2 minutes± 15 seconds (19.5 feet from the end of thegas flame to the end of the tunnel). This isconsidered (arbitrarily) as a classification of100 while the flame spread of asbestos iszero. In testing a material, classification ismade relative to these two ratings. Also, fuelcontributed and smoke density is classifiedin respect to values obtained for red oak and



Page 8 of 19


asbestos.5) ASTM D 2863—Flammability of Plastics

Using the Oxygen Index Methoda) Scope—This method describes a

procedure for determining the relativeflammability of plastics by measuring theminimum concentration of oxygen in aslowly rising mixture of oxygen andnitrogen that will just supportcombustion. This method is presentlylimited to the use of physically self-supporting plastic test specimens.

b) Significance—This method provides ameans for comparing the relativeflammability of physically self-supportingplastics.

c) Principle of Method—The minimumconcentration of oxygen in a slowlyrising mixture of oxygen and nitrogenthat will just support combustion ismeasured under equilibrium conditionsof candle-like burning. The balancebetween the heat from the combustionof the specimen and the heat lost to thesurroundings establishes theequilibrium. This point is approachedfrom both sides of the critical oxygenconcentration in order to establish theoxygen index.

d) Calculations—Calculate the oxygenindex, n, of the material as follows:

n, percent = (100 x O2)/(O2 + N2)where O2 is the volumetric flow ofoxygen, CM1/S. at the limitingconcentration determined and N2 isthe corresponding volumetric flowrate of nitrogen, CM1/S.

There are a number of other tests whichare, at times, used in the fiberglassindustry. Only the most commongenerally accepted tests have beendescribed here. Other tests can befound in textbooks and/or industryliterature. All manufacturers of anyproduct should have an in-house testingprogram, but tests should not be run justto be running tests. Rather, tests should

be run to determine how material willperform in the manufacturing process, todetermine its quality, and to determinehow the final product will perform for itsintended end use.

G. Gel Time at Room Temperature—

1) Equipment Required:a) Timer—An inexpensive stopwatch may

be picked up at a discount store; anexample of a high end alternative wouldbe a Sunshine gel meter. An alternategel meter is the Shyodu. The mechanicsbetween the two differ somewhat. ASunshine meter should be used if closecomparisons to CCP results arerequired.

b) A thermometer is required. A glassthermometer, a good pocketthermometer, or an electronicthermometer can be used.

c) Eight-ounce paper cups, wide mouthglass jars, or high-density plasticbeakers are required.

d) Some type of scale is required tomeasure both gel coat and catalyst,which must be measured consistentlyfrom test to test.

There are a number of choicesavailable, depending on the degree ofaccuracy desired. Some options include:

• Graduated paper or plastic cupsmarked in cc’s or ml’s

• A syringe or 10 ml graduatedcylinder; these can be picked up atany store that handles medicalsupplies, (e.g., food, drug, ordiscount stores)

• Small school balance or …• Balance scale.

e) Spatula and stirring stick.f) Water bath; options include:

• Fish tank, plus heater (only heatedmodels are available, so othermeans of cooling would benecessary)

• Blue M Bath.



Page 9 of 19


CCP has found the following can occur:

• Variation between gel meters (of thesame type) can be up to 1/2 minute.

• Variation in mass size (containerand volume) can be up to 12minutes.

• Variation of temperature at 76°Fversus 78°F can be more than aminute.

• Variation in repeatability (samemeter, same mass, sametemperature) can be up to 1/2minute.

Figure 11/1.A4 - Water bath

2) Measurement of Gel Time—Measured asthe amount of time from when the catalyst ismixed in until it is no longer liquid. This testis normally run at 77°F. Temperature greatlyaffects this test.a) Procedure:

1) Adjust sample to 77°F (25ºC) (±1°F).

2) Check gel meter for properoperation.

3) Set gel meter timer to zero.

4) Accurately weigh in the requiredamount of catalyst (normally 1.2percent methyl ethyl ketoneperoxide) to 100 grams of sampleunless otherwise specified.

5) Simultaneously start the power andstir catalyst into sample. Stir incatalyst for one minute. Scrape theside of the jar while stirring.

6) Place cup beneath Gel Meter.Attach glass rod to magnetic contactassembly. Center the rod in sample.Adjust the meter and rod for verticalalignment.

7) Turn on test switch.8) When buzzer sounds, timer will

stop. Turn power and test switch off.Record results.

9) Clean all equipment and set timerback to zero.

10) When measuring cure time, the geltimer can be used to determine thetime until peak exotherm. See belowfor details.

b) Report:1) Record gel time to nearest 0.1

minute.2) Report any deviations from standard

temperature and conditions.3) Measurement of Cure Time—

Measured as the amount of timefrom when the catalyst is mixed inuntil the exothermic reaction hasreached the maximum temperaturefor the 100 gram sample.

The gel-to-peak time is the timedifference between the cure timeand gel time.Additional equipment is required tomeasure the peak exotherm. A stripchart recorder illustrated in Figure11/I.A5 or a thermocouple with 1°Fgraduations can be used.The thermocouple is positioned intothe sample while liquid or as a softgel. The point of peak exotherm iscentered both vertically and



Page 10 of 19


horizontally.The sample should be insulatedfrom the bench top and protectedfrom other conditions affectingtemperature.Record the peak temperature andthe time elapsed using a stop watchor gel meter timer.Remove the thermocouple andclean the equipment.

4) Elevated Temperature (SPI)—Thistest is used when a resin will beprocessed by catalyst plus heatrather than a promoter. It provides aprocedure for determining therelative reactivity between differentbatches.

a) SPI Procedure for Running ExothermCurves1) Allow sample of uncatalyzed

polyester resin to reach roomtemperature, preferably 75°F to79°F (24ºC to 26ºC).

2) Weigh one hundred grams of resininto an eight ounce jar.

3) Weigh two grams of catalyst (50percent BPO paste) into resin ineight ounce jar.

4) Stir catalyst into resin; stir well forone minute, being careful to avoidair entrapment.

5) Pour catalyzed resin into a 19 by150 mm test tube to a depth of eight8 cm (approximately 20 grams ofresin).

6) Allow resin mixture to set at roomtemperature approximately 15minutes (plus or minus five minutes)away from strong light.

7) Submerge test tube into constanttemperature 180°F (82ºC) waterbath.

8) Insert thermocouple (iron-constantan) into center of resinmixture.

9) Record time required for resinmixture to go from 150°F to 190°F

(66 to 88ºC) as the gel time; thetime from 150°F (66ºC) to peakexotherm as cure time; and thepeak exotherm.

Figure 11/1.A5 - SPI gel time recorder

H. Grind—This test may or may not be run on gelcoats. It normally is run on the pigment concentratesused to make the gel coat.

1) A small amount of material is placed on agrind gauge and leveled with a special draw-down knife.

2) The material is visually inspected to see atwhat thickness particles appear on thescale.

3) A grind gauge (Hegman normally used) is astainless steel slab in which a variable depthtrough is milled. The scale runs from zero (4mils deep) to eight (0 mils deep).

I. Hide—This test determines at what thickness agel coat will prevent a standard colored pattern frombeing visible. The thickness at which a gel coat willhide is normally set below its minimum applicationthickness.



Page 11 of 19


Figure 11/1.A6 - Hide check..

Hide continued:1) A standard hiding paper is secured flat and

a small quantity of gel coat is placed on it.2) A draw-down bar is then used to spread the

gel coat out evenly.3) The thickness is then measured with a mil

gauge. NOTE: The gap on a draw-down barwill not deposit the same thickness of gelcoat due to friction and fluid dynamics, (e.g.,10 mil gap may give only six to eight milsfilm thickness).

4) The paper is then observed to see at whatthickness of gel coat the pattern is no longervisible.

J. Nonvolatile (NV or Resin Solids or VehicleSolids—This test is run only on the resin andmonomer or solvent portion of any system. Allpigments or fillers, if present, are separated outbefore the tests. This test is used to determine theratio of base polyester resin to monomer (usuallystyrene). This is done by boiling off monomers orsolvents which boil above 105°F (41ºC). This ratio ofbase resin to styrene can affect the cured physicalproperties of the resin. It will vary according to typeof material and application method. It can be as lowas 40 percent resin and range as high as 80 percentresin. (Refer to the data sheet of material for itsproper range.)

Two methods are used in the industry. These are:

1) Foil Solids (based on ASTM D 1259)a) A folded rectangle of smooth 6 inch by

12 inch heavy duty aluminum foil isweighed to the nearest 0.0001 gram.

b) An eyedropper full of resin(approximately one gram) is placedinside the center of the folded foil andquickly weighed to the nearest 0.0001gram.

c) The foil, with the resin inside, is placedbetween two glass plates and pressedto produce a three to four inch circle ofresin.

d) The foil is opened and placed in a clean105°F (41ºC) oven for 10 minutes.

e) After foil is removed and cooled, it is re-weighed to the nearest 0.0001 gram.

f) The percent NVM is calculated:Percent NVM =100 x (weight e - weight a)(weight b - weight a)

g) Percent monomer is 100 minus percentNVM.

This test is always done in duplicate; theresults should be within 0.4 percent of eachother.

2) Determination of Nonvolatile in PolyesterResinsa) Weigh a 60 mm aluminum dish

(containing a bent paper clip to use as astirrer) to four decimal point accuracy onan analytical balance.

b) Fill a plastic eyedropper with the resinand wipe off the resin from the outsideof the eyedropper.

c) Weigh the eyedropper to 4 point decimalaccuracy. Transfer about 0.5 gram ofresin to the aluminum weighing dish;reweigh the eyedropper to determinethe exact weight of resin transferred tothe dish.

d) Add 2 ml of toluene or toluene/acetonemix to the dish and mix into the resinusing the bent paperclip.

e) Dry the sample for 30 minutes in a200°F (93ºC) oven and reweigh to 4point decimal accuracy. The percentnonvolatile of the resin is:

100 x (weight e - weight a)weight c



Page 12 of 19


f) Run three samples and average theresults to get a final value for percentnonvolatile.

3) Pigment Solids—this test, in which aweighed gel coat is centrifuged, is notnormally run except as a double-check for aparticular reasons. The separated pigment ismixed with solvent and centrifuged, with theprocess repeated several times until thepigment is free of resin. The washedpigment is dried and weighed. Pigmentsolids are determined by:

100 x weight of dried pigmentweight of gel coat

NOTE: Be sure to subtract the weight of thecontainer.

4. PHYSICAL TESTING—Note that in all physicaltests, the test sample is preconditioned to assure fullcure. If the part is not properly cured, the full physicalproperties cannot be obtained and failure or lowreadings may result, which may not be due to thematerial. Also, it is essential that the test samples forcomparisons be constructed in an identical manner, asvariances in thickness, type of substrate, and amounts ofresin and reinforcement can change the results.

A. Tensile Strength, ASTM D 638

1) Specimen—Specimens can be molded ormachined from castings, laminates, orcompression molded plaques. They aregiven standard conditioning. Typically 1/8inch thick, their size can vary; their shape islike a dog bone, (e.g., 1/8 inch thick, 8 1/2inches long, 3/4 inch wide at the ends and1/2 inch wide in the middle).

2) Procedure—Both ends of the specimen arefirmly clamped in the jaws of a testingmachine. The jaws may move apart at therate of 0.2, 0.5, 2.0 or 20 inches per minute,pulling the samples from both ends. Thestress is automatically plotted against strain.

3) Significance—Tensile properties are usuallythe most important single indication ofstrength in a material. The force necessaryto pull the specimen apart is determined;also, how much the material stretchesbefore breaking can be determined.

B. Flexural Properties, ASTM D 790

1) Flexural Strengtha) Specimen is usually 1/8 inches by one

by 4 inches. Sheet or plaques as thin as1/16 inch may be used. The span andwidth depend upon thickness.Specimens are conditioned.

b) Procedure—The specimen is placed ontwo supports spaced 2 inches apart. Aload is applied in the center at aspecified rate and the loading at failureis used to calculate the flexural strength(psi).

c) Significance—In bending, a beam issubject to both tensile and compressivestresses.

2) Flexural Modulus—Calculated from the datagenerated during the flexural strength tests,flexural modulus is the material’s ability tohold its shape under flexural loading, or itsstiffness.

C. IZOD Impact ASTM D256

1) Specimen is usually 1/8 by 1/2 by 2 1/2inches. Specimens of other thicknesses canbe used (up to 1/2 inch) but 1/8 inch isfrequently used for molding materialsbecause of its representative average partthickness.

2) Procedure—A sample is clamped in thebase of a pendulum testing machine so thatit is cantilevered upward. The pendulum isreleased, and the force consumed inbreaking the samples is calculated from theheight the pendulum reaches on the follow-through.

3) Significance—The IZOD value is useful incomparing various types or grades ofplastics and constructions. In comparing oneplastic with another, however, the IZODimpact test should not be considered areliable indicator of overall toughness orimpact strength. Some materials are notch-sensitive and derive greater concentrationsof stress from the notching operation. TheIZOD impact test may indicate the need foravoiding sharp corners in parts made ofsuch materials.



Page 13 of 19


D. Compressive Strength, ASTM D 695

1) Specimen— Prisms 1/2 by 1/2 by 1 inch orcylinders 1/2 inch diameter by 1 inch.

2) Procedurea) The specimen is mounted in a

compression tool between testingmachine heads which exert constantrate of movement. Indicator registersloading.

b) Specimens are usually conditioned.c) The compressive strength of a material

is calculated as the psi required torupture the specimen or deform thespecimen a given percentage of itsheight. It can be expressed as psi eitherat rupture or at a given percentage ofdeformation.

Compressive Strength, ASTM D 695 continued:

3) Significance—The compressive strength ofplastics is of limited design value, sinceplastic products (except foams) seldom failfrom compressive loading alone. Thecompressive strength figures, however, maybe useful in specifications for distinguishingbetween different grades of a material, andalso for assessing, along with other propertydata, the overall strength of different kinds ofmaterials.

E. Heat Distortion Temperature, ASTM D 648

1) Specimen—Specimens measure 5 by 1/2inch by any thickness from to 1/2 inch,conditioned (oven post-cured).

2) Procedure—The specimen is placed onsupports four inches apart; a load of 66 or264 psi is placed on its center. Thetemperature in the chamber is raised at therate of 2°C + 0.2°C per minute. Thetemperature at which the bar has deflected0.010 inch is reported as ‘deflectiontemperature at 66 (or 264) psi fiber stress.’

3) Significance—This test shows thetemperature at which an arbitrary amount ofdeflection occurs under established loads. Itis not intended to be a direct guide to hightemperature limits for specific applications. Itmay be useful in comparing the relative

behavior of various materials in these testconditions, but it is primarily useful forcontrol and development purposes.

F. Glass Content

1) Procedure for Laminates With No Fillers—Asmall piece is accurately weighed andplaced in a tared crucible. The sample isthen burned in a furnace to remove all theresin. Sample residue is then weighed andpercent glass is calculated.

2) Procedure for Laminates With Fillers—Manyfillers break down under heating (e.g.,calcium carbonate and hydrated alumina)and leave a partial residue. To determinethe percent glass in a filled laminate,digestion and separation methods must beused; it is not easy to do.

G. Water Absorption, ASTM D 570

1) Specimena) For molding materials, specimens are

discs 2 inches in diameter and 1/8 inchthick. For sheet materials, specimensare bars three inches by one inch bythickness of the material.

b) Specimens are dried 24 hours in anoven at 122°F (50ºC), cooled in adessicator and immediately weighed.

2) Procedure—Water absorption data may beobtained by immersion for 24 hours in water.Upon removal, the specimens are dried witha cloth and immediately weighed. Theincrease in weight is the water absorbed. Itis reported as a percent of the originalweight.

3) Significancea) Various plastics absorb varying amounts

of water and the presence of absorbedwater may affect plastics in differentways.

b) Electrical properties change mostnoticeably with water absorption.

c) Materials which absorb relatively largeramounts of water tend to changedimension in the process. Whendimensional stability is required in



Page 14 of 19


products made of such materials,grades with less tendency to absorbwater are chosen.

Figure 11/1.A7 - Brookfield Viscometer.

H. Viscosity/Thixotropic Index (TI)/Sag—Viscosity is a material’s resistance to flow. Testsinclude:

1) Gardner-Holdt ASTM D 154 and D1545—The rate of rise of an air bubble in a samplecentered in an inverted corked glass tube ismatched against known lettered standardsat the same (77°F) temperature. Themethod has an accuracy of ± 5 percent.

2) Brookfield Viscosity—Equipment for this testincludes Brookfield Model LV and RVviscometers and spindles (see Figure11/I.A7). The procedure is as follows:

Viscosity/Thixotropic Index (TI)/Sag continued:a) Fill 8 ounce wide mouth jar to within one

inch of the jar neck.b) Adjust the temperature to 77°F (25ºC)

±0.5°F (-17ºC), being careful to avoidinclusion of foreign material. Adjust thetemperature by placing a lid on the jarand placing it in a 77°F (25ºC) constanttemperature water bath until 77°F (25ºC)

temperature is reached.3) Thixotropic materials require a different

method of measuring viscosity than thatused with non-thixotropic materials:a) Laminating resins are thixotropic, (i.e.,

have a false viscosity). This makes itessential that the model of Brookfield,spindle, speed, and time of reading arenoted. These must be in the same orderto compare viscosities with other testsor resins. Normally, the LVF model,number two spindle at six RPM, is usedand run the same way as anunaccelerated resin, except the sampleis shaken for 20 seconds before testing,and readings are taken after 2 minutes.

b) The thixotropic index (TI) is the ratio ofthe viscosities at low shear (6 RPM)divided by higher shear (60 RPM).

c) Gel coat is a thixotropic material. Thesample should be shaken prior to testingto determine the rate of recovery. Acommon procedure would measure theviscosity with the RVF model, numberfour spindle at 2, 4, and 20 RPM.

d) The Thixotropic Index is the ratio of theviscosities of low shear (2 or 2.5 RPM)divided by higher shear (20 RPM).

e) Non-thixotropic materials can bemeasured at a single speed. A commonprocedure would measure the viscositywith the LVF model, number threespindle at 30 RPM.

4) Choose the spindle to be used. Remove lidfrom container and place spindle intosample, being careful to avoid entrapment ofair bubbles beneath the spindle.a) Attach spindle to viscometer and lower

spindle to level mark indicated onspindle.

b) Start viscometer and set to specifiedspeed for testing. Allow viscometer torun for 2 minutes. Stop and takereading.

c) Determine viscosity from Brookfieldconversion table.

5) Gel Coat Sag—This is normally checked inone of two ways:



Page 15 of 19


a) Spraying the gel coat 18 to 20 mils thickonto a glass panel. A sag gauge is thendrawn across, leaving gaps. The panelis placed at a 90 degree angle andchecked later to see if the gel coat hassagged and filled the gaps.

b) A piece of one-inch tape is placed on aglass panel and 18 to 20 mils of gel coatare sprayed over the whole panel. Thetape is pulled immediately after sprayingand the panel is placed at a 90 degreeangle. Later, the amount of sag into theone-inch area is noted.

6) Weight per Gallon—Tests are run after gelcoat or resin samples have been in aconstant temperature bath at 77°F (25ºC) forat least one-half hour.

How to Check Weight per Gallon

Weigh

gallon cup

and lid.

Fill

cup

with

resin.

Place lid on

cup so that

resin comes

out small

hole in top.

Wipe off

excess.

Weigh cup and resin.

Subtract empty

weight from filled

weight.

The weight per gallon (see Figure 11/I.A8)equals the weight of the sample in gramsdivided by 10. For example:

Weight in grams 83.4 grams

Weight per gallon 8.34 pounds per gallon

Figure 11/1.A8 - Weight per gallon cup

5. SOURCES OF EQUIPMENT—Normally, labsupplies and equipment are purchased from a companythat specializes in laboratory equipment. Suchcompanies are good sources, but if a lab is being set upon a conditional basis, there are other sources of supplythat are good to know. For example, many items can bepurchased at a local drug store or discount store.Milliliters of catalyst can be measured in syringes thatare calibrated in milliliters and which can be purchasedin many states. A source that sells medical supplies forinfant children can be a source to purchase cylinders oreyedroppers that are graduated in milliliters.

For many supplies, the best reference source is theYellow Pages. Look under laboratory supplies—or, ifseeking specific items, such as paper cups, look underpaper cups first.

If a full laboratory is to be installed, obtain the catalogs ofthe laboratory supply companies.

For local supply sources, check the business telephonedirectory under Laboratory Supplies.

Major Laboratory Supply Companies

Fisher Scientific9999 Veterans Memorial DriveHouston, TX 77038800-766-7000281-820-9898www.fisherscientific.com

Thomas Scientific99 High Hill Road at I-295PO Box 99Swedesboro, NJ 08085-6099800-345-2103856-467-2000www.thomassci.com

VWR Scientific Products911 Commerce CourtBuffalo Grove, IL 60089800-932-5000847-229-0180www.vwrsp.com



Page 16 of 19


Specialized Equipment(Not normally found in scientific laboratory houses)

Paul N. Gardner316 N. E. First St.Pompano Beach, FL 33060800-762-2478(This company offers a wide selection of hard-to-finditems that are used by the plastics and paint industries,including Barcol impressors.)

Manufacturers of Specialized Equipment

Brookfield Engineering Labs (Viscometers)240 Cushing St.Stoughton, MA 02072800-628-8139

Delval Glass (Boil Test Apparatus; Corrosion Tester)1135 E. 7th StreetWilmington, DE 19801800-628-3641

Instron Corporation (Physical Testing Equipment)100 Royall St.Canton, MA 02021800-564-8378

Davis Inotek (Sunshine Gel Meters)1810 Grant Ave.Philadelphia, PA 19115803-343-1199

National and International Standards

American National Standards Institute (ANSI)Headquarters1819 L Street NWWashington, DC 20036202-293-8020www.ansi.com

American Society for Quality Control (ASQC)600 N. Plankinton AvenueMilwaukee, WI 53203800-248-1946

Test Procedures

American Society of Testing and Materials (ASTM)1828 L Street NWWashington, DC 20036

202-223-8505

NOTE: Many major libraries have ASTM Standards.



Page 17 of 19




Page 18 of 19







Page 19 of 19

APPENDIX B: Polyester Resin Bulk Storage


Part Eleven, Chapter IICopyright 2008

1. INTRODUCTION—This section covers generalinformation for those who are considering the installationof storage tanks for unsaturated polyester resins. Moredetailed information should be acquired from equipmentsuppliers and tank fabricators.

Polyester resins can be safely and economically storedand handled in bulk with properly designed equipment.

Resin temperature control is especially importantbecause polyesters are temperature sensitive andexposure to elevated temperature conditions drasticallyshortens their life. Polyester resins stored at lowtemperatures become very thick. This makes them verydifficult or impractical to handle, as well as slowing downgel and cure times.

Ideally, the storage temperature is 72 to 78°F (22 to25ºC) and should not exceed 85°F (29ºC). The expectedstorage life at ideal temperatures is about three monthsbut will vary depending upon the resin. The usage life iscut in half for every 20°F (-7ºC) over 73°F (23ºC).

Storage tanks should be inspected frequently,particularly in warm summer weather, because styrene

can polymerize on the tops and sides of the tanks,forming stalactites that sometimes break off andcontaminate the resin. The vent line should be inspectedbefore every bulk delivery to insure it is clear. A cleaningof the tank once per year is considered normal.

Agitation, or a recirculation system, is necessary for bulkstorage of polyesters, particularly thixotropic polyesters,due to the settling or flotation of certain components.

2. TOTE TANKS—In a review of packagingalternatives, shipping/handling, and recycling and wastedisposal, there are options that exhibit both advantagesand disadvantages. While tote tanks, both stainless steel

and disposable (cage exterior with polyethylenebladder), offer certain conveniences in material handlingand in addressing concerns regarding containerdisposal, they do not allow practical agitation.


2. Tote Tanks

3. Storage Tanks

4. Construction

5. Size

6. Inert Gas Atmosphere

7. Level Indicators

8. Storage Tank Cleaning

9. Pumps and Agitation

10. Valves, Pipes, and Fittings

11. Location

12. Loss Prevention Guidelines

13. Reference Material

In the case of the plastic bladder disposable tote, thehead opening does not accommodate the normal drumagitator assembly. Also, the use of plastic totes is notpermitted by NFPA, whose standards are incorporatedby reference by OSHA.

Modified mixers such as butterfly blades or chains areinadequate to agitate the entire content of the tote.Regular drum agitators are also inadequate to mix theentire content of the tote tank. In order to perform anyuseful mixing, the agitator must be operated at anadequate speed and the blade must extend sufficientlyacross the container.

As a polyester ages, some stratification may develop.This separation must be reincorporated to enable properperformance of the material and to prevent applicationdifficulties. Following the recommended procedure offive to 10 minutes mixing before each shift willaccomplish reincorporation of any stratified components.

It is important to keep in mind potential mixing difficultieswith tote tanks, and, as much as possible, to guardagainst problems generated by containers not favorableto content mixing.



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APPENDIX B: Polyester Resin Bulk StorageCopyright 2008

TOTE TANKS continued:It is also important to thoroughly inspect tote tankcontents prior to use in order to avoid problemsassociated with such containers and with stratification.

Under normal aging, storage, and transportingconditions—except long, vibration-intense hauls—stratification will not occur before two weeks of age. Thisis not an endorsement of the use of product that is lessthan two weeks old without agitation; rather, it isintended to encourage the use of product before agecreates the condition.

3. STORAGE TANKS—The storage tank may beeither vertical or horizontal. If vertical, less surface areaof the resin will be exposed to the atmosphere;therefore, there is less opportunity for evaporation andstyrene buildup. In addition, less floor area is requiredand agitation cost is minimized. The bottom of verticaltanks should be dished or coned. Horizontal tanksshould be sloped to allow complete drainage of thevessel. A vertical tank requires a higher enclosure ifinstalled inside a heated structure. A clean-out portshould be provided in the top as well as near the bottomof either type of tank.

Storage tanks may be located outside any buildingenclosure. If located outside, heating and/or cooling coilsand insulation will be required for the tank. Transfer linesshould be maintained at a constant temperature (72 to74°F (22 to 23ºC)) by means of jacketed or self-limitingheat-traced pipe.

Underground storage of polyester resins is notrecommended because the resin must be maintained at70°F (21ºC) minimum temperature, which is higher thanyear-round ground temperature. Resin viscosityincreases rapidly with a decrease in temperature.

In addition, underground tank inspection and cleaning ismore difficult, and monitoring the tank for leakage is alsomore difficult.

4. CONSTRUCTION—As a general rule, 304 gradestainless steel and phenolic-lined or epoxy-lined carbonsteel tanks are recommended for promoted resins.Some coatings used for tank lining contain TBC inhibitorto prevent formation of polystyrene gel particles. Forinformation concerning coatings and techniques used forlining of tanks, refer to the coatings manufacturer.

Some users report that DCPD-based resins have poorer

quality life in stainless steel than in lined carbon steel.Stainless steel or lined carbon steel is suitable fororthophthalic- and isophthalic-based polyesters. In atank’s service life, cleaning will be required. Usually,when hot, caustic cleaning solutions or intensemechanical abrasion must be used; all lining must bereplaced as well.

Do not use copper or brass fittings because thesemetals or alloys react with polyester resin and createcompounds that may affect the cure, color or shelf lifecharacteristics of a polyester. Cast iron or stainless steelfittings are satisfactory if designed to withstand normalpumping pressure.

It is desirable to have the tank vent attached to an airdryer or desiccator to remove all moisture from the airthat goes into the tank. Excessive moisture may affectthe resin and cause rusting in the system. A flamearrestor must be used on all vents. Check local codes forinstallation approval. Caution should be taken that theflame arrestor does not become blocked withpolystyrene buildup. (The flame arrestor should beinspected before each bulk delivery to insure it is free ofbuild-up.)

A thermometer should be installed so that thetemperature of the resin can be observed at all times.The resin should not be allowed to rise above 85°F(29ºC) for an extended period of time. Experience hasshown that in most locations— except in some areas ofthe southern United States—the temperature of astorage tank of resin which is enclosed in a well-ventilated shelter will not rise above 85°F (29ºC). It isimportant that the shelter be provided with goodventilation 24 hours a day during the hot summermonths, and that the roof, in particular, be well-insulated,or that suitable air conditioning is provided. Coolingjackets or coils could be needed for exterior tanks.

In some cases, it may be advisable to install a watersprinkler over the storage tank, especially if the tank isexposed to direct sunlight or where necessary to meetinsurance or building code regulations.

5. SIZE—The storage tank should be approximately 11/2 times the maximum size of the shipment to bestored. A normal tank wagon shipment weighs from40,000 to 45,000 pounds. Depending on the weight pergallon, a minimum tank size would be approximately6,000 gallons.



Page 2 of 6


6. INERT GAS ATMOSPHERE—If an inert gasatmosphere is used, make sure the inert gas does notbubble through the resin since this will reduce thestability of the resin.

7. LEVEL INDICATORS—Arrangements should bemade for monitoring the level of liquid in the tank.Usually a daily visual check or stick measurement isadequate. Other methods such as radar gauges ordifferential pressure (DP) cells may be used, but must beconsidered in the tank construction.

8. STORAGE TANK CLEANING—To clean apolyester resin storage tank, a detergent wash, followedby a water rinse, followed by a solvent wash, isrecommended. A cleaning compound supplier should becontacted for recommendations and suggestions for acleaning compound and a cleaning spray head. NOTE:Always use appropriate respirators while servicing thetanks; specific OSHA requirements should be adhered towhen entering a confined space. All material, includingcleaning liquids, must be disposed of in accordance withlocal and federal regulations.

9. PUMPS AND AGITATION—An air diaphragm pumpis recommended if resin is to be recirculated. It can beinstalled in such a way that it operates only when thepressure in the system is relieved. If a gear pump isused in a recirculating system, it may heat the resin,causing changes in cure and viscosity. Gear ordiaphragm pumps can be used as auxiliary equipmentfor unloading the resin, for intermittent delivery to afactory work area, or for periodic recirculation of theresin.

A gear or sliding valve pump operated at 350 to 450RPM with an external relief device may be used. Thesize of the pump will depend upon the specific gravityand viscosity of the resin involved, the quantity required,and the length of transfer line involved. Pumps should beall iron, or suitable polymer construction. No copperbearing alloys should be used.

The tank must be equipped with some means ofagitation if it is to be used for storing thixotropic resinswhich contain additives, such as a silica or an organicthickening agent. Silica tends to settle to the bottombecause of its high specific gravity and the organicmaterials tend to migrate to the top.

A fully enclosed, explosion-proof, electrically drivenagitator mounted at the top of the storage tank is anideal arrangement.

10. VALVES, PIPES, AND FITTINGS—When an epoxy-or phenolic-lined carbon steel storage tank is required,all pipe fittings and valves should be stainless steel.When a carbon steel tank is acceptable, iron valves andcarbon steel pipe and fittings are satisfactory. Transferlines to and from the storage tank should be sloped fordrainage, and vented to prevent siphoning. Drain valvesshould be installed where-ever drain problems may beencountered. Stems of valves should point up, whereverpossible, to prevent locking up due to possible resingelation.

Outlets and pipes should measure at least two inches indiameter (preferably three inches). Certain resins thatare low in viscosity (200 to 500 cps), such as those usedin the boat manufacturing industry, can be circulated orpumped through smaller diameter pipe. However, CCPrecommends that no less than one and 1/2 inches indiameter be used. Temperature must be considered ifusing ceiling mount pipe.

The hookup from a plant work area to the storage tankwill vary with the material being used, and the productbeing manufactured. When a spray gun is used, arecirculating system may be desirable. Do not use aconfiguration that creates a dead end, where resinremains static and cannot be returned to the storagetank. Resin that is not recirculated or used mayeventually gel and plug the lines.

11. LOCATION—The location of storage tanks withrespect to a work area depends on several factors. Themost important factor will be local fire hazard codes andinsurance recommendations. In general, it isrecommended that tanks be located outside or enclosedwithin a suitable fire wall. In some cases, tanks can beinstalled in a separate building, if the building is locatedan acceptable distance from the manufacturing area.

12. LOSS PREVENTION GUIDELINES—Some lossprevention items that should be considered whenplanning bulk storage facilities are:

A. Compliance with all federal, state, and localcodes (contact local fire marshall and insurancecompany for specific information).



Page 3 of 6


LOSS PREVENTION GUIDELINES continued:

B. The tank should be equipped with a pressureand vacuum relief valve to allow for normal tankbreathing while the tank is being filled and emptied.

C. A flame arrestor must be installed with the tankpressure-vacuum relief valve.

D. Copper bearing alloys should not come intocontact with resin. Exposure to these materials willinhibit resin cure.

E. All motors and electrical equipment, includinginstrumentation and lighting, should be suitable forflammable liquid storage installation. Most polyesterresins have a flash point of about 88°F.

F. Sufficient grounding should be provided for thetank wagon or tank car, storage tank, pump, motor,etc., to prevent static electricity build-up and apotential explosion hazard.

G. No smoking or open flame should be permittedin the area of the resin storage facility.

H. The storage tank should be contained asrequired by regulations.

I. Storage tanks should be equipped with overflowalarms.

13. REFERENCE MATERIAL—Excellent information onstorage may be obtained from the National FireProtection Association (NFPA).

Specific references include:

• NFPA #30—Standards of the NFPA for Storage,Handling, and Use of Flammable Liquids, asrecommended by the National Fire ProtectionAssociation.

• NFPA #70—National Electrical Code

• NFPA #77—Static Electricity as adapted by theNational Fire Protection Association.



Page 4 of 6




Page 5 of 6







Page 6 of 6

APPENDIX C: Definitions of Terms


Part Eleven, Chapter IIICopyright 2008

— A —

ACCELERATOR—Additive that reduces gel and curetime of thermosetting plastics such as polyester gel coatand resin. Also called promoter or activator.

ACETONE—In the context of FRP, primarily useful as acleaning solvent for removal of uncured resin fromapplicator equipment and clothing. VERY FLAMMABLELIQUID.

ACI—Air Catalyst Integrator (ACI) valve, which ismounted on Binks spray guns. Functions as a pointwhere catalyst and air are introduced, internally mixed,and atomized in preparation for external mixing with theresin or gel coat in a spray pattern.

ADHEREND—Any object or substance that is bonded toanother with adhesive material.

ADHESIVE—Material that unites two surfaces.

ADHESIVE FAILURE—Failure in an adhesive joint thatoccurs between the adhesive material and the adherend;contrast with Cohesive Failure.

ADDITIVE—Substance added to resin mix to impartspecial performance qualities, such as ultravioletabsorbers, and flame retarding materials (waxes,accelerators, etc.).

AIR DRY—To cure at room temperature with addition ofcatalyst but without assistance of heat and pressure.

AIR-INHIBITED RESIN—Resin which cures with a tackysurface (air inhibits its surface cure).

ALLIGATORING—Wrinkling of gel coat film resemblingalligator hide; caused by poor cure at time of contactwith styrene from a subsequent or preceding coat.

ANTIMONY TRIOXIDE—Additive used to providespecial flammability characteristics to a polyester.

ARCING—Spray method which should normally beavoided as it consists of directing spray passes by gunrotation at the wrist (arcing), as opposed to conventionalstroke from shoulder, keeping fan pattern perpendicularto mold.

AREAL WEIGHT—Weight of a fiber reinforcement perunit area (width times length) of tape or fabric.

ATOMS—Smallest possible unit of an element; maycombine with another atom or atoms to form acompound.

AUTOCLAVE MOLDING—Molding technique in whichan entire composite assembly is placed in an autoclave(or closed vessel with pressure/heat capability) at 50 to100 psi pressure to consolidate the laminate byremoving en-trapped air and volatiles.

AUTO-IGNITION TEMPERATURE—Lowesttemperature required to initiate or cause self sustainedcombustion in absence of a spark or a flame.

AUTOMATIC MOLD—Mold (for injection orcompression molding) that cycles repeatedly throughinjection phase without human assistance.

— B —

BAG MOLDING—Technique in which compositematerial is placed in rigid mold and covered with flexiblebag. Pressure is applied by vacuum, autoclave, press, orby inflating the bag.

BALANCED—Laminate design term used with aligned-fiber composites to indicate that each ply oriented at plustheta degrees is matched by a ply at minus thetadegrees. When plus theta is zero degrees, minus thetais 90 degrees. See related Symmetric. Laminate can bebalanced and not be symmetric.

BARCOL HARDNESS—Degree of material’s hardnessobtained by measuring resistance to penetration by asharp, steel point. This hardness corresponds roughly tothe degree of cure in a gel coat or laminate.



Page 1 of 18

APPENDIX C: Definitions of TermsCopyright 2008

BARCOL IMPRESSOR—Instrument invented by WalterColman during World War II to measure hardness of softmetals; manufactured by Barber-Colman Company. Twotypes are commonly used in the FRP industry. Model934 is used to check ultimate cure; Model 935 is usedfor initial readings prior to ultimate cure.

BATCH (OR LOT)—Identity for all material producedduring one operation possessing identical characteristicsthroughout.

BENZOYL PEROXIDE (BPO)—Catalyst used inconjunction with aniline accelerators or where heat isused as an accelerator.

BI-DIRECTIONAL—Arrangement of reinforcing fiberstrands in which half the strands are laid at right anglesto the other half; a directional pattern that providesmaximum product strength to those two directions.

BINDER—Bonding resin applied to glass fibers to holdthem in position in a broadgoods textile structure. Duringlamination, this resin is dissolved by the styrene inpolyester resin, and, if unsaturated, can become part ofthe final polymer network.

BINDERLESS CHOPPED STRAND MAT—Textilematerial consisting of short glass fibers held togetherwith polymer fiber cross-stitch; resembles choppedstrand mat without the binder. Also called StitchedChopped Strand Mat.

BLEEDER CLOTH—Layer of woven or nonwovenmaterial (not part of composite) that allows excess gasand resin to escape during molding process.

BLEEDING—Result of softening of backside of gel coat(typically by laminating resin, or post applied gel coat)which causes pigments (color) to reflow.

BLEED OUT—Excess liquid resin appearing at thesurface, primarily occurring during filament winding orfrom an RTM mold tube.

BOND STRENGTH—Stress required (as measured byload/bond area) to separate a layer of material fromanother material to which it is bonded. Also, amount ofadhesion between bonded surfaces.

BRACE—Integral structural element used to stiffen orstrengthen mold skin.

BREAKOUT—Separation or breakage of fibers whenedges of a composite part are drilled or cut.

BRIDGING—Condition that occurs when textile or sheetmaterial does not conform to inside edge or radius onmold or laminate surface.

BUCKLING—Failure mode usually characterized byfiber deflection rather than breaking.

BULK MOLDING COMPOUND (BMC)—Premixed blendof thermosetting resin, reinforcements, catalysts andfillers for use in closed molding process. Similar to sheetmolding compound (SMC), but mechanical qualities arenot as good and it is less expensive.

— C —CARBON (OR GRAPHITE) FIBER—Reinforcing fiberknown for its light weight, high strength, and highstiffness.

CARBOXYL—Chemical group characteristic of organicacids, which are incorporated into the polyester reactionprocess.

CAST POLYMER—Non-reinforced composite (resinused without reinforcing fibers). Combines polymers,fillers and additives as composites to meet specificapplications requirements.

CATALYST—In scientific sense, substance thatpromotes or controls curing of compound without beingconsumed in the reaction (initiator). Within thecomposites industry, free radical initiators such as MEKPare often referred to as ‘catalysts.’ Such usage isscientifically inaccurate since initiator is consumedduring usage.

CATALYST INJECTION—Used with spray equipment tocatalyze polyester at spray gun, therefore eliminatingneed to clean system within gel time of polyester.Internal mix guns require a solvent flush for cleaning gunhead.

CATALYST (PEROXIDE)—In FRP terms, substanceadded to resin or gel coat in controlled quantities tomake it gel and cure. Catalyst is reduced by accelerator,creating free radicals, which in turn initiatepolymerization.

CAVITY—Space between matched molds (pressuremolds) in which laminate is formed. Also a term for afemale mold.



Page 2 of 18


CENTIPOISE (CPS)—Unit of measure used todesignate a fluid’s viscosity. At 70°F, water is one cps;peanut butter is 250,000 cps.

CHALKING—Dry, powder-like appearance or deposit onexposed gel coat surface.

CHARGE PATTERN—Ply schedule used in parts madefrom sheet molding (SMC); pre-weighed number of SMCplies cut from SMC sheet and oriented to fill mold cavitywhen placed in mold and compressed.

CHOPPED STRAND—Uniform lengths of fibers formedby cutting continuous strand yarn or roving, usually from1/32 to two inches long. Lengths up to 1/8 inch arecalled milled fibers.

CHOPPED STRAND MAT (CSM)—Uniform lengths offibers held together by binder and added to increasecomposite part glass skin thickness. Relativelyinexpensive, generally used with other glass mats.

CLOSED MOLDING—Fabrication process in whichcomposite part is produced in a mold cavity formed byjoining of two or more tool pieces.

CLOTH—Fine weave of woven fiberglass.

COBALT—Used as accelerator for methyl ethyl ketoneperoxide catalyzed polyesters.

COEFFICIENT OF THERMAL EXPANSION (CTE)—Material’s fractional change in dimension for given unitchange of temperature.

COHESION—Tendency of single substance to adhere toitself. Also, force holding single substance together.

COHESIVE FAILURE—Failure of adhesive joint thatoccurs either within adhesive material or within one orboth ad-herends.

COMPOSITE—Material that combines fiber and bindingmatrix to maximize specific performance properties.Neither element merges completely with the other.

COMPRESSION MOLD—Mold that is open whenmaterial is introduced and that shapes material by heatand by the pressure of closing.

COMPRESSION MOLDING—See Part Six—Compression Molding.

COMPRESSIVE STRENGTH—Resistance to crushingor buckling force; maximum compressive load specimensustains divided by its original cross-sectional area.

CONDENSATION POLYMERIZATION—Polymerizationreaction in which simple by-products (e.g., water) areformed.

CONSOLIDATION—Processing step that compressesfiber and matrix to remove excess resin, reduce voidsand achieve particular density.

CONTACT MOLDING—Open-mold process thatincludes spraying gel coat, followed by hand layup orsprayup with glass and resin. Also called open molding.

CONTAMINANT—Impurity or foreign substance thataffects one or more properties of composite material.

CONTINUOUS FILAMENT MAT (CFM)—Textilematerial comprising continuous fibers, typically glass,that are swirled randomly in a construction with more loftthan chopped strand mat for the same areal weight.

CONTINUOUS FILAMENT STRAND—Individual fiberwith small diameter, flexibility and indefinite length.

CONTINUOUS LAMINATING—Process for formingpanels and sheeting in which fabric or mat is passedthrough resin dip, brought together between cellophanecovering sheets, and passed through heating zone forcure. Squeeze rollers control thickness and resin contentas various plies are brought together.

CONTINUOUS ROVING—Parallel filaments coated withsizing, gathered together into single or multiple strandsand wound into cylindrical package. May be used toprovide continuous reinforcement in woven roving,filament winding, pultrusion, prepregs, or high-strengthmolding compounds. (Also see ‘Chopped Strand.’)

COPOLYMER—Large chemical chain composed of twoor more dissimilar groups.

CORD, REINFORCING—Loosely twisted cord made upfrom rovings and designed for incorporation in moldingswhere edge reinforcement and high strength ribs arenecessary.

CORE—(1) Central component of a sandwichconstruction to which inner and outer skins are attached;common core materials include foam, honeycomb, paperand wood. (2) Channel in mold for circulation of heat-transfer media. (3) Part of complex mold tool that moldsundercut parts, also called core pin.

CORE CRUSH—Compression damage to core.



Page 3 of 18


CORE ORIENTATION—On honeycomb core, used toline up ribbon direction, thickness of cell depth, cell size,and transverse direction.

CORNER—Geometric feature characterized as pointwhere three edges come together, as in a box corner.Can be either inside corner or outside corner.

COSMETIC STABILITY—Capability of substance orpart to maintain appearance with respect to surfacesmoothness, color, gloss or other visual appearancecharacteristics.

CRAZING—Cracking of the resin due to internal stress.

CREEL—Device used to hold required number of rovingspools or other supply packages of reinforcement in de-sired position for unwinding.

CREEP—Over time, dimensional change in materialunder physical load (beyond initial elastic deformation).

CROSS-LAMINATED—Laminated so some layers areoriented at right angles to remaining layers with respectto grain or strongest direction in tension.

CROSS-LINKING—Process of bridging two polymerchains, which converts liquid to thermoset solid.

CRYSTALLINITY—Quality of molecular structure inwhich atoms are arranged in orderly, three-dimensionalpattern.

CURE—Polymerization or irreversible transformationfrom liquid to solid state with maximum physicalproperties, including hardness.

CURE TEMPERATURE—Temperature at whichmaterial attains final cure.

CURE TIME—Time required for liquid resin to reachmajority of polymerized state after catalyst has beenadded.

CURING AGENT—Catalytic or reactive agent thatinitiates polymerization when added to resin; also called‘hardener.’

— D —

DAMAGE TOLERANCE—Measure of ability ofstructures to retain load-carrying ability afterexperiencing damage (e.g., ballistic impact).

DELAMINATE—Separation of layers due to failure ofadhesion or cohesion of one component to others. Alsoincludes separation of layers of fabric from corestructure. May be associated with bridging, drilling, andtrimming.

DELAMINATION—Laminate defect that occurs due tomechanical or thermal stress and is characterized byseparation between laminae.

DEMOLD—To remove a part from a tool, or a tool froman intermediate model.

DENSITY—Weight per unit of volume, usuallyexpressed as pounds per cubic foot.

DESIGN ALLOWABLE—Limiting value for materialproperty that can be used to design structural ormechanical system to specified level of success with 95percent statistical confidence.

DIALLYL PHTHALATE (DAP)—In reinforced plastics,high-boiling monomer which will polymerize with heatand catalyst into clear, hard polymer.

DIBUTYL PHTHALATE—Lubricant for spray equipment.

DIELECTRIC—Nonconductor of electricity; ability ofmaterial to resist flow of an electrical current.

DIELECTRIC STRENGTH—Voltage required to causeelectrical arc to penetrate insulating material.

DIETHYLANILINE (DEA)—Accelerator used inconjunction with BPO catalyst, or as co-promoter forcobalt/MEKP systems.

DILUENT—Diluting (reducing or thinning) agent.

DIMENSIONAL STABILITY—Capability of substance orpart to maintain its shape when subjected to varyingforces, moments, degrees of temperature and moisture,or other stress.

DIMETHYLANILINE (DMA)—Accelerator used inconjunction with BPO catalyst; more effective than DEA.

DIMPLES—Small sunken dots in gel coat surface,generally caused by foreign particle, air void, or catalystdroplets in gel coat or laminate.

DISPERSION—Homogeneous mixture of suspendedsolid particles in liquid medium.

DISTORTION—Wavy gel coat surface reflection oftenfound in conjunction with print-through. Commonlycaused by problem in laminating system.



Page 4 of 18


DOUBLER—Extra layers of reinforcement for addedstiffness or strength where fasteners or other abrupt loadtransfers occur.

DRAFT ANGLE—Mold or mandrel’s taper or angle forease of part removal (minimum of 3 degrees isrecommended).

DRAPE—Ability of fabric (or prepreg) to conform toshape of contoured surface

DRAIN OUT—Leaking, sagging and puddling oflaminating resin from reinforcement.

DRY SPOT—Laminate defect that occurs duringmolding process and is characterized by dry, unwetfibers that have never been encapsulated by matrixmaterial.

DUPLICATION MOLD—A mold made by casting over orduplicating another article.

— E —

EDGE—Geometric feature characterized as line formedwhere two panels on different planes come together.When angle between two panels is between zero and180 de-grees, edge is inside. When angle is between180 and 360 degrees, edge is outside.

E-GLASS—Electrical glass; refers to borosilicate glassfibers most often used in conventional polymer matrixcomposites.

ELASTICITY—Capacity of materials to recover originalsize and shape after deformation.

ELASTIC LIMIT—Greatest stress material is capable ofsustaining without permanent strain remaining aftercomplete release of stress.

ELASTOMER—Material that substantially recoversoriginal shape and size at room temperature afterremoval of deforming force.

ELONGATION—Increase in length of section undertension when expressed as percentage differencebetween original length and length at moment of rupture.

ENAMEL—Gel coat or surface coat which cures tackfree.

ENCAPSULATING—Enclosing article in closedenvelope of plastics) by immersion. Milled fibers or shortchopped strands are often poured with catalyzed resininto open molds for casting electrical components.

END—Strand of roving consisting of given number offilaments is considered an end before twisting.

END COUNT—Exact number of strands contained inroving.

EXOTHERMIC HEAT—Internally developed heataccompanying chemical reaction, (e.g., curing).

EXTENDERS—Low-cost materials used to dilute orextend higher-cost resins without excessive reduction inproperties.

— F —FABRIC, NONWOVEN—Material formed from fibers oryarns without interlacing, (e.g., stitched nonwoven broadgoods).

FABRIC, WOVEN—Material constructed of interlacedyarns, fibers, or filaments .

FABRICATION—Process of making composite part ortool.

FATIGUE—Failure of material’s mechanical propertiescaused by repeated stress over time.

FATIGUE STRENGTH—Maximum cyclical stresswithstood for given number of cycles before materialfails.

FADING—Loss of color in gel coat.

FEEDEYE—Mechanism on filament winding machinethrough which roving is dispensed onto mandrel.

FELT—Fibrous material made up of interlocking fibersby mechanical or chemical action, pressure or heat.Felts may be made of cotton, glass or other fibers.

FEMALE—Archaic term formerly used to describeconcave surface or inside edge or feature.

FIBER—Individual rod of sufficiently small diameter tobe flexible, having known or approximate limit of length.

FIBER ARCHITECTURE—Arrangement of fibers andfiber bundles in textile construction.



Page 5 of 18


FIBER BLOOMING—Fiber and resin are eroded byweathering or sandpaper at different rates. Resins erodebefore fiber. As a result, fiber rich surface, when sanded,often has fibers protruding; called fiber blooming.

FIBER CONTENT—Amount of fiber in compositeexpressed as ratio to the matrix by weight.

FIBER ORIENTATION—Direction of fiber alignment innonwoven or mat laminate; most fibers are placed insame direction to afford higher strength in that direction.

FIBER PRINT—Cosmetic defect, visible on exterior gelcoat surface that resembles fiber bundle and reflectsarchitecture of glass reinforcement bundle at or near partsurface.

FIBER REINFORCED PLASTICS (FRP)—General termfor composite material or part that consists of plasticmatrix containing reinforcing fibers such as glass orcarbon having greater strength or stiffness than plastic.FRP is most often used to denote glass fiber-reinforcedplastics. ‘Advanced composite’ usually indicates high-performance aramid or carbon fiber-reinforced plastics.

FIBERGLASS—Fibers similar to wool or cotton fibers,but made from glass; sometimes call fibrous glass.Glass fiber forms include cloth, yarn, mat, milled fibers,chopped strands, roving, woven roving.

FILAMENT—Single, thread-like fiber or number of thesefibers drawn together. Variety of fiber characterized byextreme length, which permits its use in yarn with little orno twist and usually without spinning operation requiredfor fibers.

FILAMENT WINDING—Process for production of high-strength, light-weight products in which tape, roving orsingle strands are fed from creel through bath of resin(or fed dry using pre-impregnated roving) and wound onsuitably designed mandrel. Wound mandrel can becured at room temperature or in oven.

FILLERS—Relatively inert organic or inorganic materialswhich are added to resins or gel coats for special flowcharacteristics, to extend volume, and to lower cost ofarticle being produced.

FINISH—Surface treatment applied to fibers or filamentsafter they are fabricated into strands, yarn or wovenfabrics to allow resins to flow freely around and adhereto them.

FIRE POINT—Lowest temperature at which liquid inopen container will give off enough vapors to continue toburn once ignited. Fire point generally is only slightlyhigher than flash point.

FISH EYES—Circular separation in gel coat filmgenerally caused by contamination such as silicone, oil,dust, water, freshly waxed mold, or low gel coatviscosity.

FLASH POINT—Lowest temperature at whichsubstance emits enough vapors to form flammable orignitable mixture with air near the surface of thesubstance being tested.

FLEXURAL MODULUS—Ratio, within elastic limit, ofapplied stress in test sample in flexure to correspondingstrain in outermost fibers of sample.

FLEXURAL STRENGTH—Strength of material (inbending) expressed as stress of bent test sample atinstant of failure; usually expressed in force per unitarea.

FLOODING—High delivery rate from spray gun; inpigmented systems, difference in color between surfaceand bulk of film.

FLOW METER—Instrument designed to measure flowof liquid.

FRACTURE—Rupture of surface of laminate due toexternal or internal forces; may or may not result incomplete separation.

FRAMING—Structure that supports mold skin and itsbracing.

FREE RADICALS—Highly reactive molecular fragmentscapable of initiating chemical reactions, such aspolymerization of polyester resins.

FRIABLE—Term used to describe material that, whendry, can be crumbled, pulverized, or reduced to powderby hand pressure.

FRP—Fiber Reinforced Polymers; with evolution of newfibrous materials, GRP (or GRFP) becomes GlassReinforced Polymers term.

FUMED SILICA (Aerosil, Cabosil)—Thickening agentused in polyesters to increase flow or sag resistancequalities.



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— G —

GEL—Partial cure stage in plastics resins of a viscous,jelly-like state where liquid material starts to transforminto solid.

GEL COAT—Surface coat, either colored or clear,providing cosmetic enhancement and protection for thelaminate.

GEL TIME—Length of time that catalyzed polyesterremains workable after hardener is added.

GELATION—Transition of liquid to soft solid.

GENERATION—Term used to describe single step inprogression from concept to master mold to productionmold when molding composite parts with multiple moldsfrom same pattern.

GLASS TRANSITION—Reversible change inamorphous polymer between viscous or rubberycondition and hard, relatively brittle one.

GLASS TRANSITION TEMPERATURE (Tg)—Approximate temperature above which increasedmolecular mobility causes a material to become rubberyrather than brittle. The measure value of Tg can vary,depending on the test method. (A widely acceptedmethod is Differential Scanning Calorimeter—DSC.)

— H —

HAND LAYUP—Laminating by ‘hand’ as opposed tousing spray equipment. Usually requires mat and fabricreinforcements in sheet form.

HAP—Acronym for Hazardous Air Pollutants. Over 180chemicals identified by Congress in 1990 Clean Air Act,Section 112. In this law, Congress mandated EPA tocontrol emissions of these chemicals. EPA hasendeavored to do this through series of MACT standards(see ‘MACT’).

HARDENER—Substance that reacts with resin topromote or control curing action.

HEAT—Term used colloquially to indicate anytemperature above ambient (room) temperature, towhich part or material is or will be subjected.

HEAT-CONVERTIBLE RESIN—Thermosetting resinconvertible by heat to an infusible and insoluble mass.

HEAT-DISTORTION TEMPERATURE (HDT)—Temperature at which test bar deflects certain amountunder specified load (e.g., temperature at which materialsoftens).

HEAT-PRESSURE LAMINATES—Laminates moldedand cured at pressures not lower than 1000 psi.

HELICAL—Ply laid onto mandrel at an angle, often 45degree angle.

HERMETIC—Completely sealed, air-tight.

HONEYCOMB—Manufactured product of sheet metal orresin-impregnated sheet (paper, fibrous glass, etc.) thathas been formed into hexagonal shaped cells. Used ascore material for sandwich construction.

HOOP—Ply laid onto mandrel at 90 degree angle.

HOOP STRESS—Circumferential stress in cylindricallyshaped part as result of internal or external pressure.

HOT POT—Catalyst is mixed with gel coat or resin inmaterial container prior to spraying, as opposed tointernal or external gun mixing.

HYBRID COMPOSITE—Composite with two or moretypes of reinforcing fibers. Also refers to compositeprepared from a polymer which uses more than one typeof chemistry, such as XYCON

®polyester/polyurethane

hybrid material.

HYBRID RESIN—Resin with two or more types ofchemistries combined.

HYDROPHOBIC—Moisture resistant capability,moisture re-pelling.

HYGROSCOPIC—Moisture absorbing capability.

— I —

IMPREGNATE—Saturation of reinforcement with aresin.

IMPREGNATED FABRIC—See ‘Prepreg.’

INCLUSION—Physical and mechanical discontinuityoccurring within material or part.

INHIBITOR—A substance designed to slow down orprevent chemical reaction; chemical additive that slowsor delays cure cycle.

INITIATOR—Substance added to resins and gel coats tomake them gel or cure. Also see catalyst.



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INJECTION MOLDING—Method of forming plastic todesired shape by forcibly injecting polymer into a mold.

INTEGRAL HEATING—System in which heatingelements are built into a tool, forming part of the tool andusually eliminating need for oven or autoclave as heatsource.

INTERFACE—Surface between two materials in glassfibers, (e.g., area at which glass and sizing meet). Inlaminate, area at which reinforcement and laminatingresin meet.

INTERLAMINAR—Existing or occurring between two ormore adjacent laminae.

INTERLAMINAR SHEAR—Shearing force thatproduces displacement between two laminae alongplane of their interface.

IN SITU—In original position. In filament winding, usedto indicate mandrel that remains in place after winding,as opposed to mandrel that is removed after winding.

ISOTROPIC—Arrangement of reinforcing materials inrandom manner, resulting in equal strength in alldirections.

— J —JACKSTRAWING—Prominence of fiberglass patternhaving turned white in the laminate because glass hasseparated from resin due to excessive exothermic heat;usually associated with thick, resin rich laminates.Cosmetic problem only.

— K —KEVLAR

™—Strong, lightweight aramid fiber

trademarked by Dupont; used as reinforcement fiber.

— L —LAMINA—One layer of laminate; can be chopped fiberreinforced plastic layer, textile reinforced plastic layer, orcore material, etc. Plural is laminae.

LAMINATE (noun)—Panel that consists of multiplelaminae that are permanently bonded together.

LAMINATE (verb)—Action of manufacturing laminate(noun) by arranging one or more laminae. In FRP, eachlamina usually consists of a fibrous reinforcement and aresinous matrix material.

LAMINATED PLASTICS—Material consisting ofsuperimposed layers of synthetic materials that havebeen bonded together, usually by means of heat andpressure, to form single piece.

LAMINATION—Laying on of layers of reinforcingmaterials and resin, much like buildup of plywood.Several layers of material bonded together.

LAY-UP—Placing reinforcing material onto mold andapplying resin to it; can be done by hand or by usingspray-up equipment. Lay-up is sometimes used as aterm for the work piece itself.

LOW-PRESSURE LAMINATES—Laminates moldedand cured in range of pressures from 400 psi down toand including pressure obtained by mere contact ofplies.

LOW PROFILE—Resin compounds formulated for low,zero, or negative shrinkage during molding.

— M —

MACROSCOPIC—Large enough to be visible atmagnification of 60x or less.

MACT—Acronym for Maximum Achievable ControlTech-nology. Standards established by the EPA inresponse to the 1990 Clean Air Act, Section 112. Thesestandards set forth regulations for reduced emissions ofHazardous Air Pollutants (see ‘HAP’).

MALE—Archaic term formerly used to describe convexsurface or outside edge or feature.

MANDREL—Elongated mold around which resin-impregnated fiber, tape or filaments are wound to formstructural shapes or tubes.

MASS—Quantity of matter contained in a specific body.In reference to polyesters, mass is measured in terms ofweight and/or volume.

MASTER MODEL—General term for full-scalerepresentation of part design. Incorporates all geometryfor one of the part surfaces. (See also ‘Pattern’ and‘Plug.’)



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MASTER MOLD—General term for durable, robust full-scale representation of part design. Used to producemultiple copies of production mold.

MAT—Fibrous reinforcing material composed ofchopped filaments (for chopped-strand mat) or swirledfilaments (for continuous-strand mat) with binder appliedto maintain form; available in blankets of various widths,weights, thicknesses and lengths.

MATCHED-METAL MOLDING/MATCHED-DIEMOLDING—Method of closed molding in whichreinforced plastics are molded between two close-fittingmetal molds mounted in hydraulic press. Generallyconsidered most economical mass production methodfor manufacturing FRP parts in large volumes.

MATRIX—Material in which fiber reinforcements ofcomposite system is imbedded. Thermoplastic andthermoset resin systems can be used, as well as metaland ceramic.

MEK PEROXIDE (MEKP)—Abbreviation for methyl ethylketone peroxide; free radical source commonly used asinitiator for polyesters in FRP industry.

MEK (SOLVENT)—Abbreviation for methyl ethyl ketone;colorless flammable liquid commonly used in spray gunclean up procedures.

MICRO CRACKING—Cracks formed in compositeswhen thermal stresses locally exceed strength of matrix.

MICROSCOPIC—Small enough to require magnificationmuch greater than 10x to be visible.

MIL—Unit used in measuring film thickness anddiameter of fiber strands, glass, wire, etc., (one mil =.001 inch).

MILLED FIBERS—Carbon or glass used for makingfiber-filled putty or BMC strands hammer-milled intoshort fiber lengths of 1/32 inch, 1/16 inch, 1/8 inch and1/4 inch.

MODULUS OF ELASTICITY—Material property thatdescribes relationship between tension, compression orshear forces, and deflection experienced by material.Known as Young’s Modulus for isotropic materials intension. Modulus is independent of specimen geometry;therefore, it is a material property.

MOISTURE ABSORPTION—Pick-up of water vaporfrom air by a material. Relates only to vapor withdrawnfrom air by a material ; must be distinguished from waterabsorption, which is gain in weight due to take-up ofwater by immersion.

MOLD—(1) To shape plastics parts by heat andpressure. (2) Cavity or matrix into/onto which plasticscomposition is placed and from which it takes its form.Female: Made into. Male: Made onto. (3) Assembly of allparts that function collectively in molding process.

MOLD CLAMPING METHOD—RTM process featurethat describes how mold pieces are held together.

MOLD COAT—Coat of resin over bare mold. Used toseal mold and make smooth surface on which to moldparts. Essentially the same as a gel coat.

MOLD OPEN-CLOSE METHOD—RTM process featurefor separating mold pieces to allow insertion of dry glassand removal of finished part.

MOLD RELEASE—A substance used on the mold or inthe compound to prevent sticking and for ease of partrelease.

MOLD SKIN—Element of cure tool with hard surfacethat is polished to high gloss. This surface forms oneexternal face of production part during molding process.

MOLDING—Forming of part by various means, such ascontact, pressure, matched die and continuouslaminating, into given shape.

MOLECULES—Chemical units composed of one ormore atoms.

MONOFILAMENT—Single filament of indefinite length;generally produced by extrusion.

MONOMER—A relatively simple compound capable ofpolymerization with itself or with a compatible resin. Itmay also is be used to dissolve or dilute polyester.

— N —NANOMETER—Abbreviated (nm) and equal to onemillimicron or one billionth of meter, used to measurewavelengths of light.

NET SHAPE—Part fabrication resulting in finaldimensions that do not require machining or cutting.



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NON-DESTRUCTIVE INSPECTION (NDI)—Determiningmaterial or part characteristics without permanentlyaltering test subject. Nondestructive testing (NDT) andnondestructive evaluation (NDE) widely consideredsynonymous with NDI.

NPG®—Registered trademark (of Eastman Chemical

Company) for neopentyl glycol.

NON-AIR INHIBITED RESIN—Resin, cure of which willnot be inhibited or stopped by presence of air, possiblydue to surfacing agent added to exclude air from resinsurface.

NON-VOLATILE MATERIAL—Material remaining afterheating to condition short of decomposition.

— O —

ONE-OFF—Fabrication process in which single part isfabricated.

ORANGE PEEL—Backside of gel coated surface thattakes on rough wavy texture of orange peel.

ORIFICE—Opening, generally referred to regardingspray tip size.

ORIGINAL EQUIPMENT MANUFACTURER (OEM)—Com-panies that design and build products bearing theirname.

OUT-GASSING—Release of solvents, volatiles, gassesand moisture from composite parts under vacuum.

— P —

PAN (POLYACRYLONITRILE)—Base material inmanufacture of some carbon fibers.

PARALLEL-LAMINATED—Laminated so all layers ofmaterial are oriented approximately parallel with respectto the grain or strongest direction in tension. Also calledunidirectional. This pattern allows highest loading ofreinforcement, but gives maximum strength in only onedirection.

PART CONSOLIDATION—Process of compositesfabrication in which multiple discrete parts are designedand fabricated together into single part, thus reducingnumber of fabricated parts and need to join those partstogether.

PARTING AGENT—See ‘Mold Release.’

PATTERN—General term for master model that isusually constructed from single material or material type.Pattern is generally not durable and suitable forproducing only one (or small number) of molds.Sometimes used interchangeably with Plug.

PEEL PLY—Layer of material applied to a layup surfacethat is removed from the cured laminate prior to bondingoperations, in order to leave clean, resin-rich surfaceready for bonding.

PEEL STRENGTH—Strength of adhesive bond obtainedby stress that is applied ‘in a peeling mode.’

PEROXIDES—Category of compounds containingunstable O-O (or O-OH) Group: Oxygen to Oxygenatoms; used as initiators.

PHENOLIC RESIN—Thermosetting resin produced bycondensation of aromatic alcohol with aldehyde,particularly phenol with formaldehyde.

PIGMENT—Ingredient used to impart color, as in gelcoats.

PIGMENT SEPARATION—Mottled (varied color)appearance of gel coat surface.

PINHOLES—Small air bubbles in gel coat film, fewenough to count. Generally larger in size than porosity.

PLASTICS—High molecular weight thermoplastics orthermosetting polymers that can be molded, cast,extruded or laminated into objects; major advantage ofplastics is they can deform significantly without rupturing.

PLUG—General term for master model that is usuallyhand-crafted from variety of materials. Plug is generallynot durable; suitable for producing only one (or smallnumber) of molds. Sometimes used interchangeably with‘Pattern.’

PLY—Fabric/resin or fiber resin/layer bonded toadjacent layers in composite.

PLY SCHEDULE—Layup of individual plies or layers tobuild laminate (FRP). Plies may be arranged (scheduled)in alternating fiber orientation to produce multi-directionalstrength part (see ‘Fiber Architecture’).

POLYESTER (Unsaturated)—Resin formed by reactionbetween dibasic acids and dihydroxy alcohols, one ofwhich must be unsaturated (typically maleic anhydride)to permit cross-linking.



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POLYMER—Large chemical chain composed of manyrepeating groups such as polystyrene.

POLYMERIZATION—Chemical reaction of linkingmolecules or chains of molecules.

POLYVINYL ALCOHOL (PVA)—Water soluble releaseagent.

POROSITY—Small air bubbles in composite or gel coatfilm; too numerous to count. Generally smaller in sizethan pinholes.

POSTCURE—Exposure of cured resin to highertemperatures than during molding; necessary in certainresins to attain complete cure and ultimate mechanicalproperties.

POT LIFE—See ‘Gel Time.’

POTTING—Similar to encapsulating, except steps aretaken to insure complete penetration of all voids in objectbefore resin polymerizes.

PREFORM—Preshaped fibrous reinforcement formedby distribution of chopped fibers by air, water flotation, orvacuum over surface of perforated screen toapproximate contour and thickness desired in finishedpart. Also, compact pill of compressed premixedmaterials.

PREFORM MAT—Fiber reinforced mat shaped like moldin which it will be used. Eliminates need for overlappingcorners in molding.

PREHEATING—Heating of compound prior to moldingor casting in order to facilitate operation, reduce moldingcycle, or remove volatiles.

PREMIX—Mixture of resin, pigment, filler and catalystfor molding.

PREPREG—Resin-impregnated cloth, mat or filamentsin flat form that can be stored for later use. Resin oftenpartially cured to tack-free state called ‘B-staging.’Additives can be added to obtain specific end-useproperties and improve processing, storage andhandling characteristics.

PRERELEASE—Premature release of the gel coat orlaminate from the mold.

PRESSURE BAG—Tailored bag (usually rubbersheeting) placed against the in an open mold, handlayup process. Air or steam pressure (up to 50 psi) isapplied between the bag and pressure plate located overmold.

PRIMARY LAMINATE—‘Bulk’ or ‘second’ laminate;laminate applied after skin coat has cured. Generallythicker than skin coat.

PRINT-THROUGH—Transfer through gel coat film ofimage of glass strands.

PRODUCTION MOLD—Durable, robust mold used toproduce hundreds or thousands of part copies.Laminated production molds are best manufactured fromlaminated master molds.

PROFILE—Surface contour of part viewed from edge orcross section. When describing cosmetic features,profile is the roughness of surface on scale large enoughto affect visual appearance but small enough to beinsignificant with respect to dimensional functionality.Low profile corresponds to very smooth surface; highprofile corresponds to surface with greater roughness.

PROMOTER—See ‘Accelerator.’

PROTOTYPE—Process of creating test part notintended for commercial release that establishes design,material and fabrication parameters for new product.May require multiple iterations (repetitions) to arrive atfinal/commercial part design.

PULTRUSION—Automated continuous process formanufacturing composite rods, tubes and structuralshapes having constant cross section. Roving and otherreinforcements saturated with resin and continuouslypulled through a heated die, where part is formed andcured. Cured part then automatically cut to length.

— R —

RAMPING—Gradual programmed increase/decrease intemperature or pressure to control cure or cooling ofcomposite parts.

REINFORCED MOLDING COMPOUND—Reinforcedcompound in form of ready-to-use materials, asdistinguished from premix, as ‘BMC’ or ‘Gunk.’



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REINFORCEMENT—Strong, relatively inert materialmolded into plastics to improve strength, stiffness andimpact resistance. Usually fibers of glass, carbon, boronmineral, synthetic polymer, ceramic, textile, sisal, cotton,etc., in woven or nonwoven form.

RELEASE AGENT—See ‘Mold Release.’

RELEASE FILM—Impermeable film layer that does notbond to composite during cure.

RESIN—Any of class of natural or synthetic polymers,solubilized or semi-solid, generally of high molecularweight having no definite melting point. Used inreinforced products to surround and hold fibers. Mostresins are polymers.

RESIN INFUSION—To draw or force resin into dryreinforcement already in mold cavity.

RESIN PRESSURE HEAD—RTM process feature; stateof pressure across a part from injection point to ventpoint; driving force that causes resin to flow through andsaturate fiber pack.

RESIN RICH—Localized area filled with excess resin ascompared to consistent resin/fiber ratio.

RESIN STARVED—Localized area lacking sufficientresin for fiber wetout.

RESIN TEARING—Separation of vehicle from pigments/fillers in gel coat film, usually seen as black wavy lines.

RESIN TRANSFER MOLDING (RTM)—Molding processin which catalyzed resin is pumped into two-sided,matched mold where fibrous reinforcement has beenplaced. Mold and/or resin may or may not be heated.

RESIN TRANSFER SCHEME—RTM process featurethat describes pathway used to transfer resins into fiberpack.

RIBBON DIRECTION—On honeycomb core, direction inwhich honeycomb can be separated; direction of onecontinuous ribbon.

ROVING—Collection of bundles of continuous filamentseither as untwisted strands or as twisted yarns. Forfilament winding, generally wound as bands or tapeswith as little twist as possible.

RUBBER PLUNGER MOLDING—Variation of matched-die molding process which uses heated metal femalemold (or outer half) and rubber plunger male mold.Applicable for relatively small molds with modestundercuts where low pressures are involved.

— S —S-GLASS—Magnesia/alumina/silicate glassreinforcement designed to provide very high tensilestrength. Commonly used in high-performance parts.

SAGS/RUNS—Sag: Slumping of gel coat or resin film.Run: Running of gel coat film or laminating resin.

SANDWICH LAY-UP—Laminate composed of twooutside layers of reinforced material such as glass matand inside layer or layers of honeycomb, glass cloth, orother light-weight core material.

SCRIMP—Seemann Composite Resin Infusion MoldingProcess. (See ‘Resin Infusion.’) Pulls vacuum beforeresin entry.

SEALANT—Applied to joint in paste or liquid from thathardens in place to form seal.

SECONDARY BONDING—Joining together by adhesivebonding of two or more previously cured parts, orsubsequent lamination onto earlier cured laminatesurface.

SET—To convert resin into fixed or hardened state bychemical or physical action, such as condensation,polymerization, vulcanization or gelation.

SHEAR—Stress resulting from applied forces. Causedby two contiguous parts of body sliding, relative to eachother, in direction parallel to their plane of contact. Incross shear, plane of contact is composed of resin andglass fibers. In interlaminar shear (ILS), plane of contactis composed of resin only. In liquids, force andmovement of components or layers against each other.

SHEET MOLDING COMPOUND (SMC)—Ready-to-mold, glass-fiber-reinforced, thickened polyester materialprimarily used in closed molding. Similar to bulk moldingcompound (BMC), but with improved mechanicalproperties.

SHELF LIFE—Length of time uncatalyzed polyesterremains workable while stored in tightly sealedcontainer; also referenced as ‘storage life.’



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SHOT—One complete cycle on injection moldingmachine. Shot weight is measured compound deliveredto completely fill mold in injection or transfer molding.

SISAL—White fiber produced from leaves of agaveplant. Used as reinforcing filler, in short chopped lengths,to impart moderate impact resistance.

SIZING—Water-soluble solution of chemical additivesuse to coat filaments; additives protect filaments fromwater absorption and abrasion. They also lubricatefilaments and reduce static electricity (see chapter on‘Open Molding’).

SKIN LAMINATE—Thin, glass laminate applied directlyagainst gel coat to provide durability by eliminatingentrapped air, and good cosmetic quality by isolating gelcoat from subsequent laminate shrinkage due toexotherm heat.

SLAVE PUMP—Small, specifically sized pump driven bymaster gel coat or resin pump to deliver catalyst in ratioof one to three percent.

SOLVENT—Liquid used to dissolve and clean materials.

SPEC—Specification of properties, characteristics or re-quirements particular material or part must have to beacceptable to potential user of material or part.

SPECIFIC GRAVITY—Ratio of weight of any volume ofsubstance to weight of equal volume of some substancetaken as standard unit; usually water for solids andliquids, and air or hydrogen for gasses.

SPRAY-UP—Process in which glass fibers, resin andcatalyst are simultaneously deposited in mold. Roving isfed through chopper and ejected into resin streamdirected at mold. Catalyst and accelerated resin may besprayed from one or two guns. Glass resin mix is thenrolled by hand before curing.

STABILIZER—Additive for polymers which aidsmaintenance of certain properties.

STIFFNESS—Structural property that describesrelationship between forces and moments applied to,and stretching and bending deflections experienced byany item.

STRAIN—Deformation resulting from stress.

STRANDS—Primary bundle of continuous filamentscombined into single compact unit without twist.

STRESS—Internal resistance to change in size orshape, expressed in force per unit area.

STRESS CORROSION—Preferential attack of areasunder stress in corrosive environment, where such anenvironment alone would not have caused corrosion.

STRESS CRACK—External or internal cracks incomposite caused by tensile stresses; cracking may bepresent internally, externally or in combination.

STYRENE MONOMER—Unsaturated aromatichydrocarbon, used in plastics. In polyester, a reactivediluent.

SUBSTRATE—Material on which adhesive-containingsubstance is spread for any purpose, (e.g., bonding orcoating).

SURFACE PROFILE—Cosmetic quality of surface (see‘Profile’).

SURFACING AGENT—Material (commonly paraffinwax) that allows surface of polyesters to cure; limitsadhesion of another coat of resin if first is thoroughlycured. May be removed by sanding or rubbing with steelwool.

SURFACING VEIL—Used with other reinforcing matsand fabrics to enhance quality of surface finish.Designed to block out fiber patterns of underlyingreinforcements; also called ‘surfacing mat.’

SYMMETRIC—Laminate design term used withcomposites to indicate that laminate is symmetric aboutthe plane, midway through its thickness.

— T —TACK—Stickiness.

TBPB—Abbreviation for tertiary-butyl perbenzoate usedas catalyst (initiator) in high temperature molding ofpolyester resin systems.

TBPO—Abbreviation for tertiary-butyl peroctoate usedas catalyst in high speed, heated cures of polyester resinsystems.

TENSILE STRENGTH—Maximum stress sustained bycomposite specimen before it fails in tension test.

TEXTILE—Any type of sheet material made from fibersthat are woven, knitted, knotted, stitched or bondedtogether.



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THERMAL CONDUCTIVITY—Ability to transfer heat.

THERMAL SHOCK—Rapid temperature changescausing large thermal stresses.

THERMAL STRESS—Occurs when change intemperature causes materials to expand and contract atdifferent rates. Can form within and between layers oflaminate as well as between laminate and steel frame.

THERMAL STRESS CRACKING—Crazing or crackingof some thermoset or thermoplastic resins fromoverexposure to elevated temperatures or cyclictemperature variations.

THERMOCOUPLE—Assembly used to sense andrecord temperature.

THERMOPLASTICS—Polymers that can be repeatedlysoftened when heated, hardened when cooled.Thermoplastics such as polymers and copolymers ofacrylics, PET, polycarbonates, nylons, fluorocarbons andstyrene are fast becoming important engineeringmaterials.

THERMOSETS—Materials that will undergo or haveundergone chemical reaction, leading to relativelyinfusible state. Typical materials are aminos (melamineand urea), unsaturated polyesters, alkyds, epoxies andphenolics; not reformable.

THIXOTROPIC—Condition in which material possessesresistance to flow until it is agitated (mixed, pumped, orsprayed).

THIXOTROPIC INDEX (TI)—Indication of sag resistancedetermined by dividing low shear viscosity by high shearviscosity.

TOOL—Mold, either one- or two-sided, and either openor closed, in or upon which composite material is placedto make part, also ‘mold.’

TOOLING GEL COAT RESIN—Special polyestersdesigned for moldmaking.

TOUGHNESS—Measure of ability of material to absorbenergy.

— U —

UNDERCUT—Negative or reverse draft on the mold.Split molds necessary to shape pieces that are undercut.

UNIDIRECTIONAL—Refers to fibers oriented in thesame direction, such as unidirectional fabric, tape orlaminate; often called UD.

UPPER MOLD TYPE—RTM process feature thatdescribes materials and construction used for matingmold.

— V —

VACUUM BAG MOLDING—Molding process forminimizing emissions voids and maximizingreinforcement content, forcing out entrapped air andexcess resin from layups, by drawing vacuum intoflexible film draped over part. Also considered ‘ResinInfusion.’ Vacuum may be drawn after resin entry.

VACUUM-ASSISTED RESIN TRANSFER MOLDING(VARTM)—Infusion process where vacuum draws resininto one-sided mold; cover, either rigid or flexible, isplaced over top to form vacuum-tight seal.

VAPOR BARRIER—Material through which water vaporwill not pass readily or at all.

VEIL—Tissue of fibers which drapes and wets easily; ofparticular value to provide resin-rich barrier to corrosionor glass print, as in surfacing veil.

VISCOSITY—Fluid’s resistance to flow.

VOIDS—Laminate defect that occurs during moldingprocess; characterized by lack of resin material(entrapped air, un-wetted fibers).

VOLATILE MATERIAL—Material vaporizing underspecific conditions short of decomposition; nonvolatilematerial remains.

VOLATILE ORGANIC COMPOUNDS (VOC)—Carbon-containing chemical compounds (e.g., solvents orliquids) that evaporate readily at ambient or processtemperatures. Environmental, safety and healthregulations often limit exposure to these compounds, solow VOC content is preferable.

— W —WARP—Yarns running lengthwise and perpendicular tothe narrow edge of woven fabric.

WARPAGE—Dimensional distortion in composite part.



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WATER JET—High-pressure water stream used forcutting polymer composite parts.

WAX—Mold release agent or surfacing agent.

WEAVE—Pattern by which fabric is formed frominterlacing yarns. In plain weave, warp and fill fibersalternate to make both fabric faces identical. In satinweave, pattern produces satin appearance with warproving crossing over several fill rovings and under nextone (e.g., eight-harness satin would have warp rovingover seven fill rovings and under eighth).

WEAVE PRINT—Extreme form of fiber print resemblingarchitecture of woven or stitched glass ply just below ornear gel coat surface.

WEFT—Yarns running perpendicular to warp in wovenfabric.

WET LAY-UP—Application of liquid resin to dryreinforcement in the mold.

WET WINDING—Filament winding wherein fiber strandsare impregnated with resin immediately before theycontact mandrel.

WETOUT—Process in which reinforcing material can becompletely saturated with resin. Rate usually determinedvisually and measured in elapsed time.

WETTING AGENT—Surface-active agent that promoteswetting by decreasing cohesion within liquid.

WHISKER—Short single crystal fiber or filament used asreinforcement in matrix.

WIND ANGLE—Measure in degrees between directionparallel to filaments and established reference.

WINDING PATTERN—Regularly recurring pattern offilament path in filament winding after certain number ofmandrel revolutions.

WIRE MESH—Fine wire screen used to increaseelectrical conductivity. Typically used to dissipateelectrical charge from lightning or electromagneticinterference.

WITNESS MARK—Defect in gel coat surface profile thatcorresponds to some feature, either in underlyinglaminate or on/in molding surface; sometimes calledmark-off.

WOVEN ROVING FABRIC—Heavy fabrics woven fromcontinuous filaments in roving form. They drape well, arequickly impregnated are intermediate in price betweenmats and yarn cloths, and contribute to higher glasscontent.

WOVEN TAPE—Tape of various thicknesses wovenfrom continuous filament yarns.

WRINKLE—Imperfection in surface of laminate thatappears to be crease in one of outer layers; occurs invacuum-bag molding when bag improperly placed.

— X —X-AXIS—Axis in plane of laminate used as zeroreference.

— Y —Y-AXIS—Axis in plane of the laminate perpendicular tothe x-axis.

YARN—Twisted strand of roving.

YOUNG’S MODULUS—Ratio of normal stress tocorresponding strain for tensile or compressive stressesless than proportional limit of material.

— Z —Z-AXIS—Reference axis normal to laminate plane incomposite laminates.

ZERO MOLD—General term for intermediate piece oftooling that resembles production model but belongs toearlier generation. Molded from part-image mastermodel (pattern or plug); subsequently used to producemaster model.



Page 15 of 18


REFERENCES:

Advanced Composites Glossary

Blaise Technoire, San Marcos, CA

ACMA (Composites Fabricators Association)

Composites Technology (Vol. 2, No. 3, May/June 1996),Ray Publishing, Inc., Wheatridge, CO

Engineered Materials Handbook: Composites (Vol. 1,1987), Cyril A. Dostal, Sr. Ed., ASM International, MetalsPark, OH

Handbook of Composites (1982), George Lubin, Ed.,Van Nostrand Reinhold, New York, NY

Introduction to Composites, 3rd Ed. (1995), Society ofthe Plastics Industry, Washington, DC

Whittington’s Dictionary of Plastics, 3rd Ed. (1993),James Carley, Ed., Technomics, Lancaster, PA



Page 16 of 18




Page 17 of 18







Page 18 of 18

APPENDIX D: Additional Information


Part Eleven, Chapter IVCopyright 2008

In This Chapter

1. Useful Conversion Factors

2. Drums (Stick Measurement)

3. Conversion Table/Materials Coverage Charts

4. Comparison of Sizes

5. Temperature Conversion Table

6. Record of Current Products

7. Gel Coat Spray Test Sheet

8. Mixing

9. Catalyst Levels

10. Application Helpful Hints

11. Wet-to-Cured

12. Service Kit items

13. Equipment Maintenance/Cleanup Procedures

14. Catalyst Precautions

1. USEFUL CONVERSION FACTORS

PEROXIDE/COBALT/POLYESTER RESIN

1 fluid oz. MEK

peroxide*

1 gm wt. MEK peroxide

1 cc MEK peroxide

1 gm wt. MEK peroxide

= 33.1 gms MEK peroxide

= 0.0302 fluid oz. MEK peroxide

= 1.12 gms MEK peroxide

= 0.89 cc MEK peroxide

1 fluid oz. cobalt**

1 gm wt. cobalt

1 cc cobalt

1 gm wt. cobalt

= 30.15 gm. wt. cobalt

= 0.033 fluid oz. cobalt

= 1.02 gms cobalt

= 0.99 cc cobalt

1 gal. polyester resin,

unpigmented

1 lb. polyester resin

unpigmented

1 lb. polyester resin

unpigmented

= 9.2 lbs.

= 13.89 fluid oz.

= 411 cc

*9% active oxygen ** 6% solution



Page 1 of 26

APPENDIX D: Additional InformationCopyright 2008

WEIGHT VOLUME

1 gm (gram) = 0.0022 lbs.

= 0.0353 oz.

= 0.001 Kg

1 cc (cubic centimeter) = 1 ml ( milliliter)

= 0.000264 gallons

= 0.0338 fluid oz.

1 lb. (pound) = 16 oz.

= 453.6 gms

= 0.454 Kg

1 U.S. gallon = 3785 cc

= 128 fluid oz.

= 231 cubic inches

1 oz. (ounce)

(avoirdupois)

= 0.0625 lbs.

= 28.35 gms

= 0.0284 Kg

1 fluid oz. = 29.57 cc (or ml)

= 0.00781 gallons

1 Kg (Kilogram) = 1000 gms

= 2.205 lbs. (av.)

= 35.27 oz. (av.)

WEIGHT/VOLUMETRIC ADDITIVE CHART

% by Weight

.01

% by Weight

.10

% by Weight

1.0

Approx.

Volume2

gm cc1 oz.1 gm cc1 oz.1 gm cc1 oz.1

1 quart .11 .11 .004 1.11 1.11 .037 11.12 11.12 .375

1 gallon .44 .44 .015 4.45 4.45 .150 44.50 44.50 1.500

5 gallons 2.22 2.22 .075 22.25 22.25 .750 222.50 222.50 7.500

1 drum 23.58 23.58 .795 235.80 235.80 7.950 2358.50 2358.50 79.5000

% by Weight

1.2

% by Weight

1.8

% by Weight

2.0

Approx.

Volume2

gm cc1 oz.1 gm cc1 oz.1 gm cc1 oz.1

1 quart 13.35 13.35 .450 20 20 .675 22.25 22.25 .750

1 gallon 53.40 53.40 1.800 80 80 2.700 89.00 89.00 3.000

5 gallons 267.00 267.00 9.000 400 400 13.500 445.00 445.00 15.000

1 drum 2830.20 2830.20 95.000 4240 4240 143.100 4717.00 4717.00 159.00



Page 2 of 26


SPECIFIC GRAVITY FACTOR/ADDITIVES DENSITY COMPENSATION FACTOR/PRODUCTS

1. Based on the weight/gallon of 8.33 pounds for

approximate measurements; for more accurate ad-

ditions, divide the number of cc’s or oz. shown in the

table on the preceding page by the proper factor

supplied below:

970-C-981 Ethylene Glycol ......................... 1.11

970-C-903 Cobalt ........................................ 1.02

970-C-960 Styrene ...................................... 0.91

970-C-951 Inhibitor Solution ....................... 0.98

970-C-940 Wax Solution .............................. 0.91

970-C-943 Fisheye Solution ........................ 0.97

2. Based on an average weight/gallon of 9.8

pounds. For more accurate additions, divide the

number of cc’s or oz. shown in the table on the

preceding page by the proper factor supplied below:

944-W-016 .......................................................1.10

Other gel coats ................................................0.97

040-4812 ..........................................................0.91

3. Cured weight/gallon:

Polyester resins (9.0 lbs. liquid) .......................9.90

Fiberglass (roving) ........................................ 21.15

Specific gravity (factor) is the ‘ratio of the weight of any

substance to that of an equal volume of water.’ The

weight gallon of water is 8.33 pounds; therefore divide the

weight/gallon of a given substance by 8.33 (see preceding

examples). When using water as the standard, 1 cc or ml

(volume) is equal to 1 gram (weight).

The specific gravity is a very useful conversion factor for

converting volume to weight or weight to volume.

Example A:

If percent by weight is desired and the addition is to be

by volume, divide weight desired by the specific gravity.

30 grams of catalyst desired

cc graduate going to be used

30/1.12 = 27 cc’s to equal 30 grams

Example B:

If volume is known and gram weight is desired,

multiply volume by specific gravity.

2000 cc’s of white gel coat

Weight ÷ gallon of white gel coat is 10.9

10.9 ÷ 8.33 = 1.31 specific gravity

2000 x 1.31 = 2620 grams of white gel coat

Remember:

Grams to cc’s, divide by specific gravity

Cc’s to grams, multiply by specific gravity

See Drum Measurement Chart in this section to

determine how much material is in a drum.

2. DRUMS (STICK MEASUREMENT)



Page 3 of 26




Page 4 of 26


3. CONVERSION TABLE/MATERIALS COVERAGE

CHART

Conversion Table

Millimeter/Inch

MM INCHES

0.25400

0.30480

0.35560

0.40640

0.45720

0.50800

0.60960

0.71120

0.81280

0.91440

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

0.01000

0.01200

0.01400

0.01600

0.01800

0.02000

0.02400

0.02800

0.03200

0.03600

0.03937

0.07874

0.11811

0.15748

0.19685

0.23622

0.27559

0.31496

0.35433

0.39370

0.43307

0.47244

0.51181

0.55118

0.59055

0.62992

0.66929

0.70866

0.74803

0.78740

Gel Coat

Wet to Cured

Correlation

APPROX.

MILS WET

MILS

CURED

10

12

14

16

18

20

24

28

32

36

7

8

10

11

13

14

16

19

24

29

Resin to use to achieve ‘x’ percent of glass when glass

weight is known. Determine what percentage of glass is

desired; multiply glass weight by resin factor.

Desired

% of

Glass

Factor for Resin

30

31

32

33

33.33

34

35

36

37

38

39

40

2.33

2.22

2.12

2.03

2.00

1.94

1.86

1.78

1.70

1.63

1.56

1.50



Page 5 of 26


MISCELLANEOUS

10 cc (ml) per catalyst cap

1 jigger = 1.5 fl. ounces

100 gms. = approx. 3 fl. ounces gel coat

or 1 ½” x 2 ½” (in 8 oz. jar)

1 fluid ounce = 2 tablespoons (T.)

= 6 teaspoons (t.)

= 29.6 cubic centimeters (cc)

1 cup = 8 fl. oz. = 16 T. = 48 t.

128 fl. ounces = 1 gallon

approx. 36 eye drops/gram of 970-C-951 (inhibitor solution)

approx. 30 eye drops/gram of 970-C-981 (viscosity thickener)

approx. 36 eye drops/gram of catalyst

Density glass = approx. 1.6 gms./cc

or 162.5 lbs./ft.3

or 21.6 lbs./gallon

Materials Coverage

Theoretical—Assuming No Loss

WET FILM

THICKNESS Sq. Ft./Gal.

Gal./1000

Sq. Ft.

0.001” (1 mil)0.003” (3 mils)0.005” (5 mils)

0.010” (10 mils)0.015” (15 mils)0.018” (18 mils)0.020” (20 mils)0.025” (25 mils)0.030” (30 mils)0.031” (31 mils)0.060” (60 mils)0.062” (62 mils)

1600.0534.0320.0160.0107.089.080.064.053.051.027.026.0

0.631.903.106.309.40

11.2012.5015.6019.0019.5038.0038.00

CATALYZATIONThe importance of proper catalyzation when using polyesterscannot be emphasized enough. Over catalyzation, as well asunder catalyzation, can cause a variety of problems. Using the9.0% active oxygen catalyst, recommended catalyzation levelsare:

Recommended@ 77%

Mini-mum

Maxi-mum

Gel CoatsLaminatingResinsMarble Resins

1.8%1.2%1.2%

1.2%.9%.5%

3.0%2.4%2.4%

Ideal catalyst level for gel coat is 1.8%; 1.2% for laminatingand marble resins at 77°F. Add .07 catalyst to the ideal % foreach °F below 77°F to no lower than 60°F and a maximumtotal of 3.0% gel coat and 2.4% for laminating and marbleresins.

Example: When testing gel coat, ambient plant temperaturesare found to be 70°F ( or 7°F below 77°F):

7°F x .07 = 0.491.8% + 0.49 = 2.3% for that plant temperature

NOTE: Check liquid temperature of catalyst, resin and gel coatto be tested.

Units of Area

Unit Square

Inches

Square

Feet

Square

Yards

Square

Centimeter

Square Meters

Sq. inch

Sq. foot

Sq. yard

Sq. cm.

Sq. meter

1

144

1296

0.155

1550

0.006944

1

9

0.001076

10.7639

0.000772

0.11111

1

0.00012

1.19598

6.45162

929.034

8361.31

1

10000

0.000645

0.092903

0.836131

0.0001

1

Units of Length

Unit Inches Feet Yards Centimeter Meters

Inch

Foot

Yard

Mile

Cm.

Meter

1

12

36

63360

0.3937

39.37

0.08333

1

3

5280

0.03281

3.3808

0.02777

0.3333

1

1760

0.01094

1.09361

2.54

30.48

91.44

160934

1

100

0.0254

0.3048

0.9144

1609.34

0.01

1

Units of Volume

Unit Cubic

Inches

Cubic

Feet

Cubic Yards Cubic

Centimeters

Cubic inch

Cubic foot

Cubic yard

Cubic cm.

Cubic meter

1

1728

46656

0.06102

61203

---

1

27

---

35.314

---

0.03704

1

---

1.3079

16.3872

28317

764.559

1

1000000



Page 6 of 26


4. COMPARISON OF SIZES

FROM 0 to 1 INCH

(ACCEPTED DEPTH-OF-FINENESS GAUGE READINGS, INCHES,

MILLIMETERS, MICRONS, U.S. AND TYLER SIEVES)

FINENESS GAUGE

READINGS

SIEVES

Prod.

Club

Mils Hegman Inches Millimeter

s

Microns

U.S.

Std. Eq.

No.

Tyler

Mesh

10

9

0.00

0.25

0.40

0.50

0.75

8

7½

7

6 ½

0.00000

0.00025

0.00040

0.00050

0.00075

0.0000

0.0064

0.0102

0.0127

0.0191

0

6.4

10.2

12.7

19.1

8

7

0.80

1.00

1.20

1.25

1.50

6

5½

5

0.00080

0.00100

0.00120

0.00125

0 00150

0.0203

0.0254

0.0305

0.0318

0.0381

20.3

25.4

30.5

31.8

38.1 400 400

6

5

1.60

1.75

2.00

2.10

2.25

4½

4

3½

0.00160

0.00175

0.00200

0.00210

0.00225

0.0406

0.0445

0.0508

0.0533

0.0572

40.6

44.5

50.8

53.3

57.2

325

270

325

270

4

3

2.40

2.50

2.75

2.80

2.90

3

2½

0.00240

0.00250

0.00275

0.00280

0.00290

0.0610

0.0635

0.0699

0.0711

0.0737

61.0

63.5

69.9

71.1

73.7

230

200

250

200

2

1

3.00

3.20

3.25

3.50

3.60

2

1½

1

0.00300

0.00320

0.00325

0.00350

0.00360

0.0762

0.0813

0.0826

0.0889

0.0914

76.2

81.3

82.6

88.9

91.4

170 170

0

3.75

4.00

½

0

0.00375

0.00400

0.00410

0.00490

0.00590

0.0953

0.1016

0.1041

0.1250

0.1490

95.3

101.6

104.1

125.0

149.0

140

120

100

150

115

100



Page 7 of 26


COMPARISON OF SIZES continued:

FINENESS GAUGE

READINGS

SIEVES

Prod.

Club

Mils Hegman Inches Millimeter

s

Microns

U.S.

Std. Eq.

No.

Tyler

Mesh

0.00700

0.00830

0.00980

0.01170

0.01380

0.1770

0.2100

0.2500

0.2970

0.3500

177.0

210.0

250.0

297.0

350.

80

70

60

50

45

80

65

60

48

42

0.01650

0.01970

0.02320

0.02800

0.03310

0.4200

0.5000

0.5900

0.7100

0.8400

420.0

500.0

590.0

710.0

840.0

40

35

30

25

20

35

32

28

24

20

0.03940

0.04690

0.05550

0.06250

0.06610

(1/16”)

1.0000

1.1900

1.4100

1.5875

1.6800

1000.0

1190.0

1410.0

1588.0

1680.0

18

16

14

12

16

14

12

10

0.07870

0.09370

0.11100

0.12500

0.13200

(1/8”)

2.0000

2.3800

2.8300

3.1750

3.3600

2000.0

2380.0

2830.0

3175.0

3360.0

10

8

7

6

9

8

7

6

0.15700

0.18750

0.22300

0.25000

0.31250

(3/16”)

(1/4”)

(5/16”)

4.0000

4.7600

5.6600

6.3500

7.9300

4000.0

4760.0

5660.0

6350.0

7930.0

5

4

3½

5

4

3½

0.37500

0.43750

0.50000

0.62500

(3/8”)

(7/16”)

(1/2”)

(5/8”)

9.5200

11.1000

12.7000

15.9000

9520.0

11100.0

12700.0

15900.0

0.75000

0.87500

1.00000

(3/4”)

(7/8”)

(1”)

19.1000

22.2000

25.4000

19100.0

22200.0

25400.0



Page 8 of 26


5. TEMPERATURE CONVERSION TABLE

-100 to 0

C

488

493

499

504

510

516

521

527

532

538

910

920

930

940

950

960

970

980

990

1000

F

1670

1688

1706

1724

1742

1760

1778

1796

1814

1832

1000 to 3000

C

30.6

31.1

31.7

32.2

32.8

33.3

33.9

34.4

35.0

35.6

36.1

36.7

37.2

37.8

87

88

89

90

91

92

93

94

95

96

97

98

99

100

F

188.6

190.4

192.2

194.0

195.8

197.6

199.4

201.2

203.0

204.8

206.6

208.4

210.2

212.0

100 to 1000

C

-38.3

-37.8

-37.2

-36.7

-36.1

-35.6

-35.0

-34.4

-33.9

-33.3

-32.8

-32.2

-31.7

-31.1

-30.6

-30.0

-29.4

-28.9

-28.8

-27.8

-27.2

-26.7

-26.1

-25.6

-25.0

-24.4

-23.9

-23.3

-22.8

-22.2

-21.7

-21.1

-20.6

-20.0

-19.4

-18.7

-18.3

-17.8

-37

-36

-35

-34

-33

-32

-31

-30

-29

-28

-27

-26

-25

-24

-23

-22

-21

-20

-19

-18

-17

-16

-15

-14

-13

-12

-11

-10

-9

-8

-7

-6

-5

-4

-3

-2

-1

0

F

-34.6

-32.8

-31.0

-29.2

-27.4

-25.6

-23.8

-22.0

-20.2

-18.4

-16.6

-14.8

-13.0

-11.2

-9.4

-7.6

-5.8

-4.0

-2.2

-0.4

1.4

3.2

5.0

6.8

8.6

10.4

12.2

14.0

15.8

17.6

19.4

21.2

23.0

24.8

26.6

28.4

30.2

32.0

C

282

288

293

299

304

310

316

321

327

332

338

343

349

354

360

366

371

377

382

388

393

399

404

410

416

421

427

432

438

443

449

454

460

466

471

477

482

540

550

560

570

580

590

600

610

620

630

640

650

660

670

680

690

700

710

720

730

740

750

760

770

780

790

800

810

820

830

840

850

860

870

880

890

900

F

1004

1022

1040

1058

1076

1094

1112

1130

1148

1166

1184

1202

1220

1238

1256

1274

1292

1310

1328

1346

1364

1382

1400

1418

1436

1454

1472

1490

1508

1526

1544

1562

1580

1598

1616

1634

1652

C

538

593

649

704

760

816

871

927

982

1038

1093

1149

1204

1260

1316

1371

1427

1482

1538

1593

1649

1000

1100

1200

1300

1400

1500

1600

1700

1800

1900

2000

2100

2200

2300

2400

2500

2600

2700

2800

2900

3000

F

1832

2012

2192

2372

2552

2732

2912

3092

3272

3452

3632

3812

3992

4172

4352

4532

4712

4892

5072

5252

5432

C

73.3

-72.8

-72.2

-71.7

-71.1

-70.6

-70.0

-69.4

-68.9

-68.3

-67.8

-67.2

-66.7

-66.1

-65.6

-65.0

-64.4

-63.9

-63.3

-62.8

-62.2

-61.7

-61.1

-60.6

-60.0

-59.4

-58.9

-58.3

-57.8

-57.2

-56.7

-56.1

-55.6

-55.0

-54.4

-53.9

-53.3

-52.8

-52.2

-51.7

-100

-99

-98

-97

-96

-95

-94

-93

-92

-91

-90

-89

-88

-87

-86

-85

-84

-83

-82

-81

-80

-79

-78

-77

-76

-75

-74

-73

-72

-71

-70

-69

-68

-67

-66

-65

-64

-63

-62

-61

F

148.0

146.2

144.4

142.6

140.8

139.0

137.2

135.4

133.6

131.8

130.0

128.2

126.4

124.6

122.8

121.0

119.2

117.4

115.6

113.8

112.0

110.2

108.4

106.6

104.8

103.0

101.2

-99.4

-97.6

-95.8

-94.0

-92.2

-90.4

-88.6

-86.8

-85.0

-83.2

-81.4

-79.6

-77.80 to 100

C

-5.56

-5.00

-4.44

-3.89

-3.33

-2.78

-2.22

-1.67

-1.11

-0.56

0

0.56

1.11

1.67

2.22

2.78

3.33

3.89

4.44

5.00

5.56

6.11

6.67

7.22

7.78

8.33

8.89

9.44

10.0

10.6

11.1

11.7

12.2

12.8

13.3

13.9

14.4

15.0

15.6

16.1

22

23

24

25

26

27

28

29

30

31

32

33

34

35

36

37

38

39

40

41

42

43

44

45

46

47

48

49

50

51

52

53

54

55

56

57

58

59

60

61

F

71.6

73.4

75.2

77.0

78.8

80.6

82.4

84.2

86.0

87.8

89.6

91.4

93.2

95.0

96.8

98.6

100.4

102.2

104.0

105.8

107.6

109.4

111.2

113.0

114.8

116.6

118.4

120.2

122.0

123.8

125.6

127.4

129.2

131.0

132.8

134.6

136.4

138.2

140.0

141.8

C

38

43

49

54

60

66

71

77

82

88

93

99

100

104

110

116

121

127

132

138

100

110

120

130

140

150

160

170

180

190

200

210

212

220

230

240

250

260

270

280

F

212

230

248

266

284

302

320

338

356

374

392

410

413

428

446

464

482

500

518

536



Page 9 of 26


INSTRUCTIONSTo convert from Celsius to Fahrenheit:

1. Find Celsius degrees in center column.

2. Read equivalent Fahrenheit degree

in right-hand column.

To convert from Fahrenheit to Celsius:

1. Find Fahrenheit degree in center column.

2. Read equivalent Celsius degree in left hand

column.

INTERPOLATION FACTORS

0.56

1.11

1.67

2.22

2.78

1

2

3

4

5

1.8

3.6

5.4

7.2

9.0

3.33

3.89

4.44

5.00

5.56

6

7

8

9

10

10.8

12.6

14.4

16.2

18.0

-51.1

-50.6

-50.0

-49.4

-48.9

-48.3

-47.8

-47.2

-46.7

-46.1

-45.6

-45.0

-44.4

-43.9

-43.3

-42.8

-42.2

-41.7

-41.1

-40.6

-40.0

-39.4

-38.9

-60

-59

-58

-57

-56

-55

-54

-53

-52

-51

-50

-49

-48

-47

-46

-45

-44

-43

-42

-41

-40

-39

-38

-76.0

-74.2

-72.4

-70.6

-68.8

-67.0

-65.2

-63.4

-61.6

-59.8

-58.0

-56.2

-54.4

-52.6

-50.8

-49.0

-47.2

-45.4

-43.6

-41.8

-40.0

-38.2

-36.4

C

-17.8

-17.2

-16.7

-16.1

-15.6

-15.0

-14.4

-13.9

-13.3

-12.8

-12.2

-11.7

-11.1

-10.6

-10.0

-9.44

-8.89

-8.33

-7.78

-7.22

-6.67

6.11

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

F

32.0

33.8

35.6

37.4

39.2

41.0

42.8

44.6

46.4

48.2

50.0

51.8

53.6

55.4

57.2

59.0

60.8

62.6

64.4

66.2

68.0

69.8

16.7

17.2

17.8

18.3

18.9

19.4

20.0

20.6

21.1

21.7

22.2

22.8

23.3

23.9

24.4

25.0

25.6

26.1

26.7

27.2

27.8

28.3

28.9

29.4

30.0

62

63

64

65

66

67

68

69

70

71

72

73

74

75

76

77

78

79

80

81

82

83

84

85

86

143.6

145.4

147.2

149.0

150.8

152.6

154.4

156.2

158.0

159.8

161.6

163.4

165.2

167.0

168.8

170.6

172.4

174.2

176.0

177.8

179.6

181.4

183.2

185.0

186.8

143

149

154

160

166

171

177

182

188

193

199

204

210

216

221

227

232

238

243

249

254

260

266

271

277

290

300

310

320

330

340

350

360

370

380

390

400

410

420

430

440

450

460

470

480

490

500

510

520

530

554

572

590

608

626

644

662

680

698

716

734

752

770

788

806

824

842

860

878

896

914

932

950

968

986

C to F = C (1.8) + 32

F to C = (F-32) ÷1.8



Page 10 of 26


6. RECORD OF CURRENT PRODUCTS

This page is provided as a suggested format for recording CCP products currently used.

PRODUCT CODE GEL TIME CATALYST VISCOSITY

1.

2.

3.

4.

5.

6.

7.

8.

9.

10.

11.

12.

13.

14.



Page 11 of 26


6. RECORD OF CURRENT PRODUCTS

This page is provided as a suggested format for recording CCP products currently used.

PRODUCT CODE GEL TIME CATALYST VISCOSITY

15.

16.

17.

18.

19.

20.

21.

22.

23.

24.

25.



Page 12 of 26


7. GEL COAT SPRAY TEST SHEET

Purpose: 1. To determine proper amount of delivery.

2. To determine proper amount of catalyst.

3. To determine proper spray application.

GENERAL COMMENTS/RECOMMENDATIONS

1. Spray area location 1.

2. Spray person 2.

3. Type parts 3.

4. Molds (condition, type wax, etc.) 4.

5. Method of spraying (molds tilted, scaffolding, etc.) 5.

6. Staging conditions 6.

7. Mixing procedures 7.

8. Moisture/oil 8.

9. Other 9.

CALIBRATION

10. Material Batch # Batch Date 10.

11. Temperature 11.

12. Gun 12.

13. Fluid orifice 13.

14. Needle 14.

15. Air cap 15.

16. Atomizing pressure 16.

17. Hose (atomizing) 17.

18. Supply (model /size/ratio) 18.

19. Pump air pressure 19.

20. Hose (fluid) 20.

21. GPM/PPM (454 g’s is 1 pound) 21.

22. Other 22.

23. Catalyst (brand/type/lot) 23.

24. Supply 24.

25. Orifice size 25.



Page 13 of 26


GEL COAT SPRAY TEST SHEET continued:

26. Dilution ratio 26.

27. Percent catalyst desired 27.

28. Gram s/cc’s desired (line 21 x 27) 28.

29. Catalyst pressure 29.

30. Hose 30.

31. Catalyst atomizing pressure 31.

32. Hose 32.

33. Ball(s) setting 33.

34. Catalyst delivery 34.

35. Percent catalyst (line 34÷21) 35.

36. Control gel time 36.

37. Gun gel time 37.

38. Film gel time 38.

39. Layup time 39.

40. Other 40.

APPLICATION

41. Identification (mold #/part #) 41.

42. Start/finish/total time 42.

43. Spray distance 43.

44. Number of passes 44.

45. Mils per pass 45.

46. Total mils 46.

47. Other 47.



Page 14 of 26


8. MIXING

MIXING

DO NOT OVERMIX.

OVERMIXING CAN

REDUCE VISCOSITY.

GEL COAT SHOULD

BE MIXED FOR

10 MINUTES

PRIOR TO

SHIFT STARTUP.

THE GEL COAT

SHOULD BE

MIXED TO THE SIDES

OF THE CONTAINER.

USE THE LEAST AMOUNT

OF TURBULENCE

POSSIBLE.



Page 15 of 26


9. CATALYST LEVELS

CATALYST LEVEL

IDEAL CATALYST LEVEL FOR GEL COAT

IS 1.8% AT 77ºF.

The following catalysts are recommended for use with CCP Gel Coats:

Luperox® DDM-9

Luperox® DHD-9

Chemtura Hi-Point 90

Norox® MEKP-925

Norox® MEKP-9

MINIMUM APPLICATION TEMPERATURE IS 60ºF.

MAXIMUM

CATALYST LEVEL

IS 3.0%

MINIMUM

CATALYST LEVEL

IS 1.2%



Page 16 of 26


ADJUST CATALYST LEVEL 0.07

FOR EACH DEGREE FROM 77ºF.

IF COOLER THAN 77ºF, ADD 0.07 UP TO A CATALYST LEVEL OF 3.0%.

EXAMPLE#1: TEMPERATURE OF GEL COAT IS 70ºF.

7 X 0.07 = 0.49 + 1.8% = 2.3%

IF WARMER THAN 77ºF, SUBTRACT 0.07 DOWN TO

A MINIMUM CATALYST LEVEL OF 1.2%.

EXAMPLE #2: TEMPERATURE OF GEL COAT IS 85ºF.

8 X (-0.07) = (-0.56) + 1.8% = 1.24%



Page 17 of 26


10. APPLICATION HELPFUL HINTS

APPLICATION

HELPFUL HINTS

1. MIX GEL COAT PER RECOMMENDATIONS.

2. CHECK CALIBRATION ON A REGULAR

BASIS.

3. THE FIRST PASS SHOULD BE A THIN, WET,

CONTINUOUS FILM.

4. MAINTAIN A WET LINE.

5. SPRAY 3 PASSES FOR A TOTAL OF 18

MILS

(± 2 MILS) WET.



Page 18 of 26


11. WET-TO-CURED

GEL COAT WET-TO-CURED

THICKNESS CORRELATION

Low VOC (HAP) Gel Coat

versus

Standard Gel Coat

MILS WET

10

12

14

16

18

20

24

28

32

36

MILS CUREDStandard Gel Coat

7

8

10

11

13

14

16

19

24

29



Page 19 of 26


MILS CUREDwith Low VOC (HAP)

Gel Coat*

5 to 7%

Improvement* Dependent on the actual VOC (HAP) of the gel coat, and on application and environmental conditions.

12. SERVICE KIT ITEMS

SERVICE KIT ITEMSListed in this section are tools and equipment necessary for checking out field problems with polyester. The list can also

be used as a basic reference for items a customer should have in order to run trouble-shooting and calibration tests.

Item Source

Scales—Ohaus 0-250 gms

0-2000 gms

1

1

Single pan balance 0-2610 gms 2

1

Applicator sticks 1

Tongue depressors 2

Graduated

cylinders

10 mil

100 mil

1000 mil

2

2

2

Paper tubs 2

Graduated

measuring cups

3 oz/85 MI 2

Measurematic

Catalyst Dispenser

2

Small plastic

bottles and eye

droppers

7

Disposable gloves 2

Disposable particle

mask

2

Disposable

coveralls

Size M

Size L

2

Disposable shoe

covers

One size 2

Paint strainer 2

Magnifier flashlight 10X 3

Respirator 1



Page 20 of 26


Item Source

Pocket magnifier (for

dry film thickness)

1

Mil gauges 3

Atomizing air gauge

and regulator

#73-125 8

Drum mixer 5-21-0065 8

Putty knife 5

Can opener 5

Pocket thermometer -30°F to

+120°F

1

Adjustable wrench 5

Pliers 5

Screwdrivers 5

Masking tape 1

Barcol impressor #934 6

Safety glasses 1

Tes Tape glucose

enzymatic test strip

7

(catalyst detector)

Draw-down bars and

paper

3

Weight/gallon cup 3

SOURCES

1. Chemical/Scientific supplier (check Yellow

Pages under ‘lab supplies’).

2. United Industrial Sales Co.

4410 Glenbrook Road

Willoughby, OH 44094

or other fiberglass supplier

3. Paul N. Gardner Company

316 NE First Street

Pompano Beach, FL 33060

Ph: 800-762-2478

4. BYK-Gardner

Rivers Park II

9104 Guilford Road

Columbia, MD 21046

Ph: 800-343-7721

5. Hardware store or similar establishment

6. Barber Colman

1354 Clifford Ave

Love’s Park, IL 61132-2940

Ph:815-637-3222

7. Drug store

8. ITW Poly-Craft

4100 McEwen, Suite 125

Dallas, TX 75244

Ph:972-233-2500

Customer Service: 800-423-3694

Fax: 972-702-9502



Page 21 of 26

13. EQUIPMENT MAINTENANCE AND CLEANUP PROCEDURES

EQUIPMENT MAINTENANCESpray guns and support equipment represent a considerable investment. A planned program of maintenance should be

put in place to protect that investment. Also, refer to equipment manuals for specific instruction.

A maintenance program should include the following review and checklist:

A. Maintain spare parts for all spray guns, pumps,

hoses, catalyst injectors or catalyst slave

pumps:

1) Air cap, nozzle and needle.

2) Packings and gaskets.

3) Extra hoses and fittings.

4) Extra gauges.

B. Continuously monitor the following:

1) Catalyst flow.

2) Condition of all hoses (no kinks or

frayed hoses).

3) Spray pattern and technique.

4) Contamination—if present, remove.

5) Use of proper protective equipment.

C. Daily checklist:

1) Drain water traps every three hours—

more often if needed.

2) Mix gel coat adequately but not

excessively.

Do not overmix gel coats. Overmixing can

break down a gel coat’s viscosity, thereby

increasing sag tendencies. Overmixing also

causes styrene loss, which could contribute

to porosity. Gel coats should be mixed once

a day, for 10 minutes. The gel coat should be

mixed to the sides of the container with the

least amount of turbulence possible. Air

bubbling should not be used for mixing. It is

not effective and only serves as a potential

for water or oil contamination.

3) Inventory catalyst for day’s use. Check

catalyst level. If using a slave arm

pump, check for air bubbles.

4) Start pumps with regulator backed all

the way out. Open valve and charge air

slowly, checking for leaks. Do not let the

pump cycle (both strokes) more than 1

per second.

5) To shut down:

a) Turn off all air pressures and back

regulator out.

b) Bleed lines.

c) Store pump shaft down to keep wet.

d) Check for material and catalyst

leaks.

6) Remove spray tips and clean

thoroughly. Lightly grease all threads.

Protect tips from damage.

7) Secure the area. Remove all solvents

and check for hot spots. Remove and

properly dispose of any collections of

catalyzed material, catalyst/material

combinations, trimming, and FRP dust.

D. Weekly (or more often, if needed) checklist:

1) Calibrate each spray gun for material

flow.

2) Calibrate each catalyzer or catalyst

slave pump for catalyst flow.

3) Check gel time of gel coat through the

gun versus gel time of known control.

4) Clean filter screens.

SPRAY EQUIPMENT CLEANUP PROCEDURES



Page 22 of 26

These instructions are not all-inclusive. For specific

instructions, consult equipment manuals.

A. Relieve all pressure from pump and lines.

B. Place pump in container of solvent.

C. Wipe down outside of pump.

D. Remove and clean spray tips.

E. Turn up pressure slowly until pump barely

pumps with trigger pulled.

F. Run two to three gallons of solvent through

pump and lines, spray into bucket for proper

disposal, then relieve pressure. Do not let

the pump cycle (both strokes) more than

one per second.

G. Carefully open bypass at filter.

H. Remove and clean filter—replace if

necessary.

I. Immerse pump in clean solvent.

J. Repeat Steps F through G.

K. Wipe hoses and gun own.

L. Grease or lubricate appropriate parts as

necessary.

M. Inspect for worn parts and order

replacements.

N. Make sure pump is stopped in the down

position to prolong packing life.

0. Relieve all pressure and back regulators off

to ZERO setting.

14. CATALYST PRECAUTIONS

CATALYST PRECAUTIONSSTORAGE

Methyl ethyl ketone peroxide (MEKP) formulations should

be stored as follows:

STORE IN ORIGINAL CONTAINER IN A COOL

PLACE. For maximum shelf life storage temperature

should be below 85ºF (29ºC), If peroxide freezes,

thaw at room temperature. Do not apply heat. Large

quantities (>500 lbs.) should be stored in a separate

free-standing structure in accordance with all laws,

regulations, and insurance carriers.

STORE SEPARATELY. Prevent contact with foreign

materials, contaminants, PROMOTERS, RED OR

WHITE LABEL ITEMS, IRON, BRASS, COPPER and

other OXIDIZABLES or other flammable items. MEKP

must be stored away from the manufacturing area

and separated from other combustibles or materials

that could induce decomposition. Failure to observe

these precautions could result in fire or explosion.

NEVER STORE IN A REFRIGERATOR THAT

CONTAINS FOOD OR THAT IS USED FOR FOOD

STORAGE!

POST SIGNS AROUND STORAGE AREA

READING:

DANGER!—NO SMOKING!—KEEP AWAY!

FLAMMABLE STORAGE!

AUTHORIZED PERSONNEL ONLY!

SAFETY AND HANDLING

MEKP catalyst formulations are oxidizing materials and

should be handled with care. MEKP catalyst can be

hazardous to personnel and equipment if not handled in a

safe manner.

FIRST AID—AVOID CONTACT AND INHALATION!

EYES—Immediately wash eyes with large volumes of

water for 15 minutes and get medical aid.

SKIN—Immediately remove contaminated clothing

and rewash before wearing. Wash well with soap and

water.

CATALYST PRECAUTIONS continued:

SWALLOWING—Administer milk or water and call a

physician immediately. DO NOT induce vomiting.

Have physician contact the appropriate state Poison

Control Center which will be listed under Emergency

Numbers on the first page of the local phone

directory.



Page 23 of 26


INHALATION—Remove to fresh air and get

immediate medical aid. Prolonged inhalation should

be avoided.

Personnel should wear proper PROTECTIVE CLOTHING

when handling MEKP catalyst, such as SAFETY

GLASSES, GLOVES, APRONS, AIR MASKS, BARRIER

CREAMS, etc.

Drain containers thoroughly and flush empty containers

with water-detergent mixture before discarding. Work area

should be well ventilated. All work surfaces, containers,

etc. in contact with MEKP should be scrupulously cleaned

and all contamination avoided. Work area should be

equipped with sprinklers.

Never bring into manufacturing area more MEKP catalyst

than can be used immediately. Rotate stocks

systematically according to date received or lot number, in

order that the oldest materials are used first.

DO NOT MIX OR STORE WITH ACCELERATORS

such as dimethyl or diethylaniline or cobalt

naphthenate, thiols, or other promoters, accelerators

or reducing agents. Special care must be taken to

avoid contamination with combustible materials,

strong oxidizing or reducing agents or accelerators for

polymerization reactions, etc.

Equipment and containers for handling MEKP catalyst

should be made of 304 or 316 stainless steel

(vented), glass (vented), Teflon®, polypropylene,

polyethylene, Tygon, silicone rubber, or high purity

aluminum.

Dilution is not recommended. If the user elects to

dilute material, use only pure suitable diluents.

NEVER USE ACETONE!

IF SPILLAGE OCCURS, use a non-combustible

material like vermiculite or perlite absorbent to soak

up spilled material. Using a non-sparking shovel

and/or dust pan, collect the saturated absorbent and

deposit in double polyethylene bags and wet

thoroughly with water. Remove the polyethylene bags

of absorbent to a remote protected outside area that

is safe from the spread of fire should the material self-

ignite. Do not place bags in direct sunlight. For proper

disposal contact a hazardous waste disposal

company, local authorities, or state EPA. Any usage,

paper towels, etc.,should be disposed of in this same

manner. Be sure to remove any isolated or hidden

pockets of MEKP.

FIRE

MEKP catalyst does not ignite easily but will burn very

vigorously after ignition. This peroxide must be kept away

from all sources of heat and ignition such as radiators,

steam pipes, direct rays of the sun, open flames, and

sparks.

SMALL FIRES—Use Class B Fire Extinguishers (dry

chemicals, foam or carbon dioxide) or water fog.

Halon is also recommended.

LARGE FIRES—NOTIFY FIRE DEPARTMENT

IMMEDIATELY! Evacuate all non-essential

personnel. Fight fire from a safe upwind distance with

water, preferably a fog spray or foam. AVOID

INHALATION OF FUMES—use air masks if

available.

KEEP ENDANGERED CONTAINERS COOL WITH

WATER SPRAY TO PREVENT OVERHEATING.

FLUSH DAMAGED AREA WELL WITH WATER—

AVOID WASHING MEKP DOWN SEWERS. FIRE

MAY RESULT! DO NOT ATTEMPT CLEAN-UP

UNTIL DAMAGED AREA IS AT ROOM

TEMPERATURE AND ALL SIGNS OF DANGER

ARE GONE.

All information in this bulletin is based on testing, observation, and other

reliable sources of data. It is presented in good faith and believed to be

accurate. The buyer and/or user assumes all risks and liabilities arising

from the use or in connection with the use of these products. CCP

neither assumes nor authorizes any person or company to assume for

it any liability in connection with the sales and/or use of its products,



Page 24 of 26



Page 25 of 26







Page 26 of 26

CCP Composites Cookbook

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