Lac

[lak]

Lac is the scarlet resinous secretion of a number of species of Lac-producing insects, the most commonly cultivated of which is Kerria lacca.

The lac-producing insect is also known by numerous synonyms such as Laccifer lacca, Carteria lacca and Tachardia lacca. Kerria lacca belongs to the lac insect family Kerriidae, one of some 28 families of scale insects and mealy bugs comprising a large group of about 8000 described species of plant sucking insects, a few of which produce similar natural products (e.g., cochineal and crimson). Thousands of these tiny insects colonize branches of suitable host trees and secrete the resinous pigment. The coated branches of the host trees are cut and harvested as sticklac.

The harvested sticklac is crushed and sieved to remove impurities. The sieved material is then repeatedly washed to remove insect parts and other soluble material. The resulting product is known as seedlac. The prefix seed refers to its pellet shape. It is used in violin and other varnish and is soluble in alcohol. This type of lac was used in the finishing of 18th century fowling guns in the US. Seedlac which still contains 3-5% impurities is processed into shellac by heat treatment or solvent extraction.

Lac production is found in Assam and other parts of North-East India, Bangladesh, Myanmar, Thailand, Laos, Vietnam and parts of China. It is also found in Mexico.

Host trees

Kerria lacca can be cultivated on either cultivated or wild host trees.

In India the most common host trees are

In Thailand the most common host trees are

Rain tree (Samanea saman)
Pigeon pea (Cajanus cajan)

In China the common host trees include

Pigeon pea (Cajanus cajan)
Hibiscus species

In Mexico

Barbados nut (Jatropha curcas)

Uses

The use of lac dye goes back to ancient times. It has been used in India as a skin cosmetic and dye for wool and silk. In China it is a traditional dye for leather goods. The use of lac for dye has been supplanted by synthetic dyes. It is used in medicine as hepatoprotective and antiobesity drug.

References

http://www.szgdocent.org/resource/ff/f-arth3a.htm
http://www.beadnshop.com/lac-kashmiri-beads/ Beads and other products produced with the help of lac. Manufacturing process and information on site.
http://www.jatropha.de/ The Jatropha Website, for production in Mexico