These lacquers are also used on wooden products, furniture primarily, and on musical instruments and other objects. General Motors Oakland automobile brand automobile was the first (1923) to introduce one of the new fast drying nitrocelluous lacquers, a bright blue, produced by DuPont under their Duco tradename. Prior to their introduction, mass produced automotive finishes were limited in colour, with Japan Black being the fastest drying and thus most popular. Quick-drying solvent-based lacquers that contain nitrocellulose, a resin obtained from the nitration of cotton and other cellulostic materials, were developed in the early 1920s, and extensively used in the automobile industry for 30 years. R = (CH 2) 7CH=CHCH 2CH=CHCH 2CH=CH 2 and others. R = (CH 2) 7CH=CHCH 2CH=CH(CH 2) 2CH 3 or There are more than four forms of urushiol which is written as thus: In the lacquering of the Chinese musical instrument, the guqin, the lacquer is mixed with deer horn powder (or ceramic powder) to give it more strength so it can stand up to the fingering. Advanced decorative techniques using additional materials such as gold and silver powders and flakes ("makie") were refined to very high standards in Japan also after having been introduced from China. The process is called "kanshitsu" in Japan. It is used not only as a finish, but mixed with ground fired and unfired clays applied to a mould with layers of hemp cloth, it can produce objects without need for another core like wood. Later, pigments were added to make colours. There is some evidence that its use is even older than 8,000 years from archeological digs in China. Raw lacquer can be "coloured" by the addition of small amounts of iron oxides, giving red or black depending on the oxide. Unlike Japanese and Chinese Rhus verniciflua resin, Burmese lacquer does not cause allergic reactions it sets slower, and is painted by craftsmen's hands without using brushes. The end result is similar but softer than the Chinese or Japanese lacquer. Lacquer yielding trees in Thailand, Vietnam, Burma and Taiwan, called Thitsi, are slightly different they do not contain urushiol, but similar substances called "laccol" or "thitsiol". It sets by a process called "aqua-polymerization", absorbing oxygen to set placing in a humid environment (called "furo" or "muro" in Japanese, means "a bath" or "a room") allows it to absorb more oxygen from the evaporation of the water. The trees must be at least 10 years old before cutting to bleed the resin. Lacquer mixed with powdered cinnabar is used to produce the traditional red lacquerware from China. Known applications of lacquer in China included coffins, plates, music instruments and furniture. Trade of lacquer objects traveled through various routes to the Middle East. With the discovery of lacquer ware in Japan dating back to Jōmon period, conflicting theories claim that technology may have been independently developed in Japan. It was believed that Japan had also been using lacquer from ancient times, but the systematic process of application was developed by the Chinese. The contemporary theory held that from China, knowledge of lacquer technology was introduced to Korea, and from there to Japan. The Chinese treated the allergic reaction with shell-fish. The fresh resin from the Rhus trees causes urushiol-induced contact dermatitis and great care is required in its use. Insect lac was introduced to India from Persia (Iran). In India the insect lac was first used from which India first extracted a red dye, later what was left of the insect was a grease that was used for lacquering objects. There are two types of lacquer: one is obtained from the Rhus tree and the other from an insect. The process of lacquer application in India is different from China and Japan. Lacquer skills became very highly developed in India and Asia, and many highly decorated pieces were produced. The phenols oxidize and polymerize under the action of an enzyme laccase, yielding a substrate that, upon proper evaporation of its water content, is hard and fairly resistant to mechanical stress. In order for it to set properly it requires humidity and warm temperature. Urushiol-based lacquers differ from most other lacquers in that they are slow-drying, water based, and set by oxidation and polymerisation, rather than by evaporation alone. The active ingredient of the resin is urushiol, a mixture of various phenols suspended in water, plus a few proteins. They do not, however, stand up well to ultraviolet light. These lacquers, made from the resin of the tree Rhus verniciflua, produce very hard, durable finishes that are both beautiful, and very resistant to damage by water, acid, alkali or abrasion. The earliest known lacquers were made in China or Japan, with earliest discovery dating back to 7000 B.C.
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