LAC

leading aircraftsman.

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(as used in expressions)

Lac Léman

Lac Moero

Saint Jean Lac

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▪ resinous secretion

also spelled  Lack,  

      sticky, resinous secretion of the tiny lac insect, Laccifer lacca, which is a species of scale insect. This insect deposits lac on the twigs and young branches of several varieties of soapberry and acacia trees and particularly on the sacred fig, Ficus religiosa (Bo tree), in India, Thailand, Myanmar (Burma), and elsewhere in Southeast Asia. The lac is harvested predominantly for the production of shellac (q.v.) and lac dye, a red dye widely used in India and other Asian countries. Forms of lac, including shellac, are the only commercial resins of animal origin.

      As early as about 1200 BC, lac products were being used in India as plastic and decorative materials. During the 17th century, after traders had introduced lac dye and, later, shellac to Europe, lac became commercially important there. Eventually, lac products came to be used in most of the industrialized countries of the world.

      The word lac is the English version of Persian and Hindi words that mean “hundred thousand,” indicating the large number of the minute insects required to produce lac. In fact, about 17,000 to 90,000 insects are needed to produce one pound of shellac.

      The maximum yield of resin and dye is obtained by gathering stick lac (i.e., the twigs with their living inhabitants) in June and November. Lac dye is obtained from ground stick lac by extraction with hot water or hot sodium carbonate solution.

      Seed lac is the resin, freed from the lac dye. After the seed lac is melted, strained through canvas, spread, cooled, and flaked, it becomes the shellac of commerce. The palest orange lac is the most valuable. See also cochineal.

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