Fibers and

Threads

Cloth can yield:class &individual characteristics.

Matching fibers involves comparing:type of fiber, color, type of dye,production method.

Classification of FiberClassification of FiberUntil 19th C. only natural fibers used tomake clothing• Mineral – think earth… glass, asbestos• Animal – silk, wool, fur• Vegetable (plant) – cotton, linen, hemp• Synthetic – rayon, nylon, acetate

– Currently 50% all fibers are synthetic

Many different natural fibers that come from plants and animals are used in the production of fabric.

http://www.fireflydiapers.com/articles/diaperarticle_naturalfibersabsorb.htm

Cotton fibers are the plant fibers most commonly used in textile materials

The animal fiber most frequently used in the production of textile materials is wool, and the most common wool fibers originate from sheep.

Natural Fibers

More than half of all fibers used in the production of textile materials are synthetic or man-made.

Nylon, rayon, and polyester are all examples of synthetic fibers.

Cross-section of a man-made fiber

Synthetic Fibers

Fibers under a microscope

Synthetic Fibers: Petroleum is the basis for these fibers, and they have very different characteristics from other fibers.

Monomers are joined together to form polymers. The fibers produced are spun together into yarns.

They have no internal structures, and under magnification they show regular diameters.

Comparison of Natural and

Synthetic Fibers Visual Diagnostics of Some Common Textile Fibers

under Magnification

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are needed to see this picture.

• Fibers can be twisted (spun) into:any length, thick or thin, loose, or tight.

• A blend can be made to meet different

needs such as resistance to wrinkling.

• Fibers can be woven into fabrics. – Threads are arranged side by side (the

warp). – More threads (the weft) then are

woven back and forth crosswise in one of a number of different patterns through the warp.

Weave Patterns

What are some tests that will help to identify a fiber?

Burn Test Burning a fiber can give you hints to the type of fabric based on what you see:

• Characteristic odors• Residues• Beading• Smoke or smolder?

• Flame or no flame?

Solvent/Solubility Test

Can the fiber dissolve in certain solvents?Often the following

solvents are used to help ID a fiber:

• HCl• NaOH• Bleach• Acetone• Dry-Cleaning Solvent

Stain Test(They show these types of tests in laundry commercials all the time.)

• Will blood stain the cloth?

• Will blood ‘bead’ off?

• Is this lipstick?

Microscopic Tests

What can you see using the microscope?

• Weave• Braids• Folds & Twists• Translucency• Fraying• Was it cut or ripped?

Collection Methods The two most common ways to collect

fiber evidence are:

#1. The Tape Method… (you probably have done this before when you have held a critter and they have left half of their white fur on your black shirt.)

#2. Sweeping/Vacuuming Method: work well but collects LOTS of other debris.

So… Where else besides clothing do you look for fibers?

•Rugs•Drapes•Couches•Pillows•Cars

You can really learn a lot of stuff

from fiber and other trace material.

Stuff like:• Skin cells on ropes…

(kidnapping, murder, suicide?)

• Fibers on duct tape….

(kidnappers’ tool of choice…)

• Rope characteristics:

# of strands, twist direction, weave pattern, color, diameter, weight

• Soil, rocks, debris

give possible location

• Building materials

• Wood & plant material