How is lac made by scale insects used in shellac and varnishes?

Lac is a resinous secretion produced by the Indian lac insect, a type of scale insect. To produce commercial shellac, the raw material—known as stick lac—is harvested from tree branches, crushed, and processed to remove the red lac dye. The remaining resin, called seed lac, is melted, strained, cooled, and flaked into the amber-colored product known as shellac.12

Shellac functions as a natural thermoplastic, meaning it softens when heated and hardens upon cooling. Its use in varnishes and finishes stems from its ability to dissolve in alcohol. These alcohol-based solutions are widely applied as primers and finishes for wood furniture and floors. Additionally, alkali emulsions of shellac are utilized in the production of sealers, cements, and self-polishing waxes. Beyond these applications, shellac serves as an intermediate in nitrocellulose lacquers and has historically been used in various manufactured goods, including sealing wax and molded articles.2