Source: Shellac is the purified product of lac, the red, hardened secretion of the insect Laccifer (Tachardia) lacca Kerr. This tiny insect sucks the sap of selected trees and bushes, and secretes lac as a protective covering. The name lac is said to derive from lakh, the Sanskrit word for one hundred thousand, a reference to the very large number of insects involved in producing appreciable amounts of the product.

Lac is cultivated in India, Thailand, and Burma.

The whitest lac is produced by insects infesting the kusum tree (Schleichera trijuga). The harvester cuts twigs coated with lac into small pieces called sticklac. The crude material is ground and soaked in water to remove debris and insect bodies. The remaining material is soaked in sodium carbonate, which removes laccaic acid, a complex mixture of at least four structurally related pigments. The resulting granules retain the yellow pigment erythrolaccin and are dried to form seedlac. Further treatment by melting, evaporating, or filtering yields shellac.

Uses of Shellac

The most common use is as a furniture finish, but it has also been used in the pharmaceutical industry, in dentistry, and in cosmetics.

Side Effects of Shellac

Little data are available. One report discusses contact cheilitis.

Toxicology:

Little data are available regarding toxicity. One study investigated the short-term inhalation toxicity in rabbits of a hair spray-containing shellac; the product did not induce any significant toxicologic problems. Shellac NF is food grade and is listed as Generally Recognized as Safe (GRAS) by the FDA. One report discusses contact cheilitis to shellac. Another report reviews bezoars (accumulations of foreign material in the stomach) such as shellac. This unusual collection in the GI tract, if untreated, may lead to anorexia, weight loss. bleeding, or perforation.

Summary: Shellac is a crude natural material composed of variable constituents. It is produced from insect Laccifer secretions, then treated to form the final product. Shellac is used in furniture finishing, tablet coatings and matrices, dentistry, and cosmetics. The crude product poses little health hazard, although commercial products that dilute shellac in solvents may pose a health problem.

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