shellac, solution of lac in alcohol or acetone. In commerce the name is applied to the resinous substance (lac) itself rather than to the solution. It ranges in color from orange to light yellow depending upon the extent to which it has been purified; the darker shellacs are the less pure. When bleached it is known as white shellac. Applied to surfaces such as wood and plaster, the solution forms a hard coating upon evaporation of the solvent. Shellac is widely used as a spirit varnish, as a protective covering for drawings and plaster casts, for stiffening in the manufacture of felt hats, in making sealing wax, and in electrical insulation.