Shellac is generally made from two ingredients, raw seed lac and ethyl alcohol. In fact, most companies want to purify shellac as completely as possible—impurities from the bug, the cocoon etc. are removed, as are natural waxes. Shellac is generally shipped in dry or flaked form and is re-moisturized with an alcohol solvent, generally denatured alcohol. Some companies add ingredients to lengthen the shelf life of their product but will not reveal these proprietary additives. Shellac that is bleached (or made into clear shellac) are dissolved in sodium carbonate and centrifuge to remove insolubles and then bleached with sodium hypochlorite.
Some of the main uses of shellac in different fields are :
- Shellac dissolves in wide variety of alkaline or rapidly drying alcoholic solvents but is resistant to a number of other solvents particularly hydrocarbons.
- Its films shows excellent adhesion to a wide variety of surfaces, possessing high gloss, hardness and strength.
- Shellac is powerful bonding material with low thermal conductivity and a small coefficient of expansion. Its thermal plasticity and capacity of absorbing large amounts of fillers are noteworthy.
- Its electrical properties include high dielectric strength, low deelectric constant and characteristic freedom from tracking.
- It is resistant to the action of ultraviolet rays.
- Shellac is non-toxic.