28 adhesives
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Transcript of 28 adhesives
WOOD MATERIALS TECHNOLOGY
4th Edition
Chapter 28Adhesives
AdhesivesShelf life
– Best before date – how long the glue will keep in its container or packaging
Pot life– The time that the glue remains usable in a pot– Also known as open assembly time
Closed assembly time– The time you have to adjust and cramp the pieces before
the glue starts to set
How a glue works
Specific adhesion– The holding power of
the glue itself
Mechanical adhesion– The grip it has on the
material, e.g. cracks, crevices, pores
Types of adhesive
Scotch glue/pearl gluePVA glueCasein glueContact/impact glueFormaldehyde glueEpoxy resinsAliphatic (yellow) glueSuperglueHot melt glue
Scotch glue/pearl glue
Scotch/pearl/animal glueWater soluble – dissolves in
waterStrong smellNot heat resistantLong shelf lifeMust be prepared in glue
potUsed for veneering
PVA glue
PolyVinyl Acetate (PVA) – Water soluble– Water-resistant types
available– Ready to use from container– Strong bond– Requires cramps– Sets in 4 – 12 hours– Mainly used for bonding wood
Epoxy resin
Expensive Glue and hardener – 2 partVery strong glueBonds different materialsQuick setting
Impact/contact glue
Used for veneering Solvent-based Harmful if inhaledStrong smellAvoid skin contact
Fixing veneer or laminate to wooden base
Using contact glue
Superglue
Very strong bond Quick-setting Expensive – only for small jobsWater-resistant glueBonds many different materialsAvoid skin contact – harmful
Hot melt glue
Glue sticks are melted in the hot gun
Hot liquid glue is squeezed out with the trigger
Glue sets quickly
Applying glueMethods
Fit joints without glue and check
Apply glue to pieces Assemble joints carefullyCramp pieces lightly and
firmlyWipe off all excess glue with
a clean damp clothCheck for square
Assembly
Quiz
What do the letters PVA stand for?
– PolyVinyl Acetate
Name the tool and state its use
• Hot melt glue gun− An electrically heated gun
used for heating and applying hot melt glue
Which glue might be used to bond two metals together?
– Epoxy resin glue– Superglue
Where might you use animal glue?
• Scotch/animal/pearl glue− Usually used for
veneering
Suggest a suitable adhesive to be used when forming the laminated piece of this project
– PVA glue– Casein glue
Suggest a suitable adhesive for bonding the veneer to the base
A suitable glue might be– Contact glue– Scotch/animal glue