Êtes-vous un étudiant de l'EPFL à la recherche d'un projet de semestre?
Travaillez avec nous sur des projets en science des données et en visualisation, et déployez votre projet sous forme d'application sur GraphSearch.
Concept
Lac
Résumé
Lac is the resinous secretion of a number of species of lac insects, of which the most commonly cultivated is Kerria lacca.
Cultivation begins when a farmer gets a stick 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 material. The resulting product is known as seedlac. The prefix seed refers to its pellet shape. Seedlac, which still contains 3–5% impurity, 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.
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, lacquerware, skin cosmetic, ornaments 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. These are being used very widely nowadays.
Kerria lacca can be cultivated on either cultivated or wild host plants.
In India the most common host plants are:
Dhak (Butea monosperma)
Ber (Ziziphus mauritiana)
Kusum (Schleichera oleosa) (reported to give the best quality and yield)
In Thailand the most common host plants are
Rain tree (Albizia saman)
Pigeon pea (Cajanus cajan)
In China the common host plants 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.
Source officielle
À propos de ce résultat
Cette page est générée automatiquement et peut contenir des informations qui ne sont pas correctes, complètes, à jour ou pertinentes par rapport à votre recherche. Il en va de même pour toutes les autres pages de ce site. Veillez à vérifier les informations auprès des sources officielles de l'EPFL.