The term 'lacquer' is sometimes rather indiscriminately used to represent various different materials including natural resin varnishes and synthetic coatings based on polyesters, acrylics and cellulose derivatives. Oriental lacquer, which the Japanese call urushi, is, however, a unique material. The main raw material used in the lacquer process, that is the lacquer itself, is made from the sap of several species of trees of the family Anacardiaceae, the most important of which is Rhus vernicifera (also called Rhus vernicifua and sometimes considered to belong to the genus Toxicodendron). Other species of importance include Rhus succedana from Taiwan and Vietnam and Melanorrhoea usitata found in Thailand and Burma. Other members of the same family growing in South East Asia and other tropical zones produce similar materials. These include mango, and cashew which is used by some commercial restorers and craftsmen working in Japan.
In China where use of the sap originated, archaeological evidence has continued to push back the earliest known date for lacquer items at least to about 700 bc (Kuwayama, 1988). In 1978 there were estimated to be 410 000 000 lacquer trees in China with an annual production of some 2 000 tons of lacquer. About 250 g of sap are obtained from each tree. This huge output reflects the use of lacquer in China as an industrial plastic used in the manufacture of insulators and oil pipelines as well as domestic wares and art objects. In Japan, where the use of lacquer is confined to art objects and domestic wares, production in the same year was estimated at five tons.
Lacquer has been used in the production of a wide range of decorative art objects, sculptures and buildings. Variations in method are found all over Asia but the technique was brought to perfection by the Japanese. Rhus species are relatives of the sumac and poison ivy and are toxic, producing in most people an allergic reaction with skin rashes and blistering which can be severe. Once cured, however, the risk of unfavourable reaction is very slight. Cashew lacquer, a less toxic substitute for urushi lacquer, has been marketed as Polycite by the Mitsubishi Petrochemical Company.
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