Lac is the resinous secretion of a number of species of lac insects, of which the most commonly cultivated is Kerria lacca.
The word lac is derived from the Sanskrit word lākshā’. It was used for both the lac insect and the scarlet resinous secretion it produces. This resin has been used for making traditional and tribal bangles, and still used as sealing wax by the India Post. It is also 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.
Kerria lacca can be cultivated on either cultivated or wild host plants.
In India the most common host plants are Pongam o honge (Millettia pinnata), generally planted as avenue trees by the forest department, well known in traditional uses for its medicinal properties, Dhak/Palas (Butea monosperma), Ber (Ziziphus mauritiana) and Kusum (Schleichera oleosa).
In Thailand the most commun trees are the rain tree(Albizia saman) and Caiano (Cajanus cajan). In China Caiano (Cajanus cajan) and 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.
The use of lac dye goes back to ancient times. It was used in ancient India and neighbouring 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 coloured 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.
For dyeing fabric. The achieved color is burgundy red.