Lac

For other uses, see Lac (disambiguation).

Lac tubes created by Kerria lacca

Resin secreted by the female lac bug on trees is processed and sold as dry flakes.

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

Cultivation begins when a farmer gets a stick (broodlac) that contains eggs ready to hatch and ties it to the tree to be infested. Thousands of lac insects colonize the branches of the 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. Seedlac which still contains 3–5% impurities is processed into shellac by heat treatment or solvent extraction.

The leading producer of lac is Jharkhand, followed by the Chhattisgarh, West Bengal, and Maharashtra states of India. Lac production is also found in Bangladesh, Myanmar, Thailand, Laos, Vietnam, parts of China, and Mexico.

Etymology

See also: Lacquer

The word Lac is derived from the Sanskrit word lākshā' (लाक्षा) representing the number 100 thousand, which was used for both the Lac insect (because of their enormous number) and the scarlet resinous secretion it produces that was used as wood finish, skin cosmetic and dye for wool and silk in ancient India and neighbouring areas. Lac resin was once imported in sizeable quantity into Europe from India along with Eastern woods.

Host trees

Pongam or Honge (Millettia pinnata) is a native of India and grows in profusion, generally planted as avenue trees by the forest department. It's renowned for its shade and is well known in traditional uses for its medicinal properties. It is also grown as a host plant for lac insects. The tree is also one of the food plants for Common Cerulean (Jamides celeno).

Kerria 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), (Reported to give the best quality and yield).
• 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)

Estimated yields per tree in India are 6–10 kg for kusum, 1.5–6 kg for ber, and 1–4 kg for dhak. The bugs' life cycles can produce two sticklac yields per year, though it may be better to rest for six months to let the host tree recover.

Harvesting

Lac is harvested by cutting the tree branches that hold sticklac. If dye is being produced, the insects are kept in the sticklac because the dye color comes from the insects rather than their resin. They may be killed by exposure to the sun.

On the other hand, if seedlac or shellac is being produced, most insects can escape because less colored pale lac is generally more desired.

Uses

The use of lac dye goes back to ancient times. It was used in ancient India and neighboring areas as wood finish, skin cosmetic and dye for wool and silk. In China it is a traditional dye for leather goods. Lac for dye has been somewhat replaced by the emergence of synthetic dyes, though it remains in use, and some juices, carbonated drinks, wine, jam, sauce, and candy are colored using it.

Lac is used in folk medicine as a hepatoprotective and anti-obesity drug. 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 United States. the lac is highly inflammable as mentioned in the ancient Indian epic Mahabharata.

Production levels

India exported significant amounts of sticklac derivatives, especially lac dye, from the 1700s to the late 1800s. Production declined as synthetic dyes emerged, and after the late 1940s, production of seedlac and shellac also declined due to replacement.

In the mid-1950s, India annually produced about 50,000 tons of sticklac and exported about 29,000 tons of lac; by the late 1980s the figures were about 12,000 tons and 7,000 tons, respectively. By 1992-93, India's lac exports fell further to 4,500 tons. In the same period, Thailand's production increased somewhat, with annual lac exports of around 7,000 tons in the 1990s, mainly of seedlac. China exported only about 500 tons of shellac per year in the 1990s but produced more lac internally: 4,000-5,000 tons of sticklac and 2,000-3,000 tons of shellac in Yunnan province, with additional, smaller production in Fujian province. While India, Thailand, and China are the major lac producers, Bangladesh, Myanmar, Vietnam, and Sri Lanka also play small roles.

Species

• Kerria lacca - the true lac scale.
• Paratachardina decorella - the rosette lac scale.
• Paratachardina pseudolobata - the lobate lac scale.

See also

• Carmine (E120) - Another pigment extracted from an insect.
• Lacquer - A product that was at one time made from lac, but in modern common usage now refers to a separate product with similar properties.
• Shellac - A protective coating.

External links

• Indian Institute of Natural Resins and Gums - IINRG, formerly Indian Lac Research Institute - ILRI
• FAO - Insect dyes - Lac - Summary of Basic Information