shellac

Shellac is a natural resin secreted by lac insects of the genus Kerria, most notably Kerria lacca. The insects inhabit various host trees in Asia, especially in the Indian subcontinent, where they produce resin that coats twigs and branches. Harvested resin is processed into flakes, refined, and dissolved in alcohol to form a viscous coating used for finishes and coatings.

Shellac comes in waxed and dewaxed forms and in several color grades, including blonde, orange, and garnet. It is soluble in alcohol but insoluble in water, drying to a hard, glossy film. Shellac films are moderately resistant to acids but sensitive to heat and ultraviolet light; older finishes can amber with age and exposure.

Primary uses include traditional wood finishing for furniture, musical instruments, and antiques, where it provides a warm, high-gloss surface that can be buffed. It is also used as a glazing agent in certain foods and candies (E904) and as a protective coating in some pharmaceuticals and cosmetics. In restoration work, dewaxed shellac is often preferred for compatibility with common solvents and finishes.

Historically, shellac has been used for centuries in the Indian subcontinent, with European trade expanding its use in the 18th and 19th centuries. The rise of synthetic lacquers reduced its dominance in some applications, but shellac remains valued for certain traditional finishes and niche uses.

Safety and handling: shellac finishes are generally considered non-toxic and edible when used as a glaze; however, dust can irritate the skin or lungs, and the resin is soluble in alcohol, requiring proper handling of solvents. It is not typically used for exterior, weather-exposed applications.