lac

lac, resinous exudation from the bodies of females of a species of scale insect ( Tachardia lacca ), from which shellac is prepared. India is the chief source of shellac, although some is obtained from other areas in Southeast Asia. The insects feed on the sap of the twigs of certain tropical trees, some of which are cultivated for this purpose. The resinous secretion hardens upon exposure to air and forms a protective incrustation around the female and young, which are thus held fast to the twigs. The twigs are scraped to remove the incrustation; this crude lac material is known as stick lac. If the stick lac is crushed, the wood splinters and other foreign materials removed, and the red coloring matter produced by the insects dissolved out, the residue when dried is seed lac. Seed lac is melted, filtered, and stretched into thin sheets, which are broken into flakes when cool. Orange-colored shellac is made from these flakes by dissolving them in alcohol. White shellac is made from bleached lac.

The Columbia Electronic Encyclopedia, 6th ed. Copyright © 2012, Columbia University Press. All rights reserved.

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