Shellac – A Short History and Description

2013.11.09

Shellac begins with a resin secreted by the tiny female lac scale (primarily Kerria lacca), native to India and Southeast Asia.  The Sanskrit word lākṣā meaning “one hundred thousand” was given to the insects, which cover the branches in vast numbers.  Then by extension it was applied to the secretions, which have been processed into dyes and finishes for thousands of years.  Both lacquer and shellac share this root, although modern lacquers are complex chemical polymers no longer derived from insect or plant resins.

The sticklac is crushed, sieved, and washed to produce seedlac and lac dye.  The seedlac is further refined and manipulated into buttonlac and shellac.  Shellac exhibits a range of colors from garnet to lemon, depending on the host tree species and harvest season.  Bleach processing produces the lighter shades up to an almost transparent finish, but the most widely used color is the mid-range orange or amber.  The resin contains about five percent wax, which can reduce the transparency and water resistance.  Dewaxed shellac is a convenient option, or the wax can be separated with siphoning.

Shellac is considered foodsafe and is used as a glazing for hard candies, fruits, and pills (especially timed-release).  Some phonograph records were made from a compound including shellac as the binder, before the widespread use of vinyl.  There are many other historical and current uses for the material besides finishing furniture.

The primary solvent for shellac is alcohol, and the resulting liquid form has a shelf life of six months to three years (this can vary considerably due to storage conditions).  Over time, the shellac loses water resistance and the ability to solidify into a cured finish.  When fresh and properly applied, shellac dries to a relatively hard and durable high-gloss bioadhesive polymer, essentially a natural plastic.  It is not as scratch- or water-resistant as lacquer or polyurethane, but shellac can be retouched with a new coat because the previous coat(s) will partially dissolve and merge with the new coat.

Beginning around 2010, there has been a global shortage of shellac due to poor harvests, thus driving up the costs.  Currently a pound of shellac flakes retails for $25 – $40.