Lac

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For other uses, see Lac (disambiguation).

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Lac is the scarlet resinous secretion of the insect Laccifer lacca. Laccifer lacca belongs to the family of scale insects and mealy bugs Coccoidea a large family of plant sucking insects. 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 shellac 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.

[edit] Host trees

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

In India the most common host trees are
- Dhak (Butea monosperma)
- Ber (Ziziphus mauritiana)
- Kusum (Schleichera oleosa)
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

[edit] 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.

It has a mention in the ancient Vedic book called the Manusmrti, or the 'Laws of Manu'. This book is the source of all the laws regarding caste in India. It lays down who can eat with whom, who can marry whom, who can touch whom; and it also lays down how those who infringe those laws should be punished. Thus, for example, it is decreed: "XII. 4. If the shudra [a member of the labouring caste, or an Untouchable] intentionally listens for committing to memory the Veda, then his ears should be filled with molten lead and lac; if he utters the Veda, then his tongue should be cut off; if he has mastered the Veda his body should be cut to pieces."

Shellac (the refined form of lac) is used in several industrial applications, such as:

Surface coatings
Textiles
Printing
Cosmetics and pharmaceuticals
Adhesives
Electrical industry

Shellac was also used to manufacture 78 rpm phonograph records from 1897 until the 1950s, when vinyl plastic, being much more durable, was used instead.