An adhesive is a substance used to join two or more parts together to form a single unit. Adhesives are widely used in the manufacture of veneers, plywoods and other laminated wood products and for fixing wall and ceiling linings, tiles and other flooring. The use of adhesives has many advantages over traditional methods of bolting, riveting and welding. Glue is a general term used to denote an adhesive substance. Following are the different types of adhesives.
Animal protein glue: It is obtained by boiling the waste pieces of animal skins, bones etc. in hot water. Animal glue creates a strong and tough joint and is easy to apply. But it is affected by wet and humid conditions.
Natural resin glue: It is prepared from natural resin. It is used for labelling, building paper etc.
Synthetic Resin Glue: This glue is based on synthetic resin. This can be either a thermosetting glue or a thermoplastic glue. Thermosetting becomes permanent after the glue sets. Thermoplastic glue can be made into plastic again by reheating.
Nitrocellulose glue: It is made from pyroxylene, a nitrated cellulose. It is obtained by treating cellulose with nitric acid. It forms films, which adhere strongly to the glass.
Rubber glue: It is prepared by dissolving rubber in benzene. It is used to join rubber, plastic, glass, etc.
Special glue: It is specially formulated for joining metals. Cycle weld is a modified form of rubber and is used to join aluminum sheets. Araldite is another type of special glue. It is used to join light metals.
Starch glue: It is prepared from vegetable starch. It has good strength in dry conditions. But it is not moisture resistant. It is cheap and used in interior quality of plywood.
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