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Lacquer is a type of hard and usually shiny coating or finish applied to materials such as wood or metal. It is most often made from resin extracted from trees and waxes and has been in use since antiquity.
Asian lacquerware, which may be called "true lacquer", are objects coated with the treated, dyed and dried sap of Toxicodendron vernicifluum or related trees, applied in several coats to a base that is usually wood. This dries to a very hard and smooth surface layer which is durable, waterproof, and attractive in feel and look. Asian lacquer is sometimes painted with pictures, inlaid with shell and other materials, or carved lacquer, as well as maki-e and given other further decorative treatments.
In modern techniques, lacquer means a range of clear or pigmented that dry by solvent evaporation to produce a hard, durable finish. The finish can be of any sheen level from ultra to high gloss, and it can be further polished as required. Lacquer finishes are usually harder and more brittle than oil-based or latex paints and are typically used on hard and smooth surfaces.
In terms of modern finishing products, finishes based on shellac dissolved in alcohol are often called shellac or lac to distinguish them from synthetic lacquer, often called simply lacquer, which consists of synthetic polymers (such as nitrocellulose, Butyrate ("CAB"), or acrylic resin) dissolved in lacquer thinner, a mixture of various organic . Although synthetic lacquer is more durable than shellac, traditional shellac finishes are nevertheless often preferred for their aesthetic characteristics, as with French polish, as well as their "all-natural" and generally food-safe ingredients.
It has been confirmed that the lacquer tree has existed in Japan since nearly 12,600 years ago in the incipient Jōmon period. This was confirmed by radioactive carbon dating of the lacquer tree found at the Torihama shell mound and is the oldest lacquer tree in the world found as of 2011.
target="_blank" rel="nofollow"> 1万2千年前のウルシ木片 世界最古、福井で出土, The Nikkei, November 6, 2011 Lacquer was used in Japan as early as 7000 BCE, during the Jōmon period. Evidence for the earliest lacquerware was discovered at the Kakinoshima "B" Excavation Site in Hokkaido. The ornaments woven with lacquered red thread were discovered in a pit grave dating from the first half of the Initial Jōmon period. Also, at Kakinoshima "A" Excavation Site, earthenware with a spout painted with vermilion lacquer, which was made 3200 years ago, was found almost completely intact. Kakinoshima Excavation Site Hokkaido Government
During the Shang dynasty (1600–1046 BC), the sophisticated techniques used in the lacquer process were first developed and it became a highly artistic craft, although various prehistoric have been unearthed in China dating back to the Neolithic period. The earliest extant Chinese lacquer object, a red wooden bowl,Stark, Miriam T. (2005). Archaeology of Asia. Malden, MA : Blackwell Pub. p. 30. . was unearthed at a Hemudu culture (5000–4500 BC) site in China.Wang, Zhongshu. (1982). Han Civilization. Translated by K.C. Chang and Collaborators. New Haven and London: Yale University Press. p. 80. . By the Han dynasty (206 BC – 220 AD), many centres of lacquer production became firmly established.
The knowledge of the Chinese methods of the lacquer process spread from China during the Han dynasty, Tang dynasty and Song dynasty dynasties. Eventually it was introduced to Korea and Japan.Trade of lacquer objects travelled through various routes to the Middle East. Known applications of lacquer in China included coffins, music instruments, furniture, and various household items. Lacquer mixed with powdered cinnabar is used to produce the traditional red lacquerware from China.
From the 16th century to the 17th century, lacquer was introduced to Europe on a large scale for the first time through Nanban trade. Until the 19th century, lacquerware was one of Japan's major exports, and European royalty, aristocrats and religious people represented by Marie-Antoinette, Maria Theresa and The Society of Jesus collected Japanese lacquerware luxuriously decorated with maki-e. Urushi once attracted the world urushi-joboji.comMasayuki Murata. 明治工芸入門 p.24. Me no Me, 2017 The terms related to lacquer such as "Japanning", "Urushiol" and " maque" which means lacquer in Mexican Spanish, are derived from Japanese.
The trees must be at least ten years old before cutting to bleed the resin. It sets by a process called "aqua-polymerization", absorbing oxygen to set; placing in a humid environment allows it to absorb more oxygen from the evaporation of the water.
Lacquer-yielding trees in Thailand, Vietnam, Myanmar and Taiwan, called Thitsi, are slightly different; they do not contain urushiol, but similar substances called laccol or thitsiol. The result is similar but softer than the Chinese or Japanese lacquer. Burmese lacquer sets slower, and is painted by craftsmen's hands without using brushes.
Raw lacquer can be "coloured" by the addition of small amounts of , giving red or black depending on the oxide. There is some evidence that its use is even older than 8,000 years from archaeological digs in Japan and China. Later, pigments were added to make colours. It is used not only as a finish, because if 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. The process is called "kanshitsu" in Japan. 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.
There are a number of forms of urushiol. They vary by the length of the R chain, which depends on the species of plant producing the urushiol. Urushiol can also vary in the degree of saturation in the carbon chain. Urushiol can be drawn as follows: , where:
R = (CH2)14CH3 or
R = (CH2)7CH=CH(CH2)5CH3 or
R = (CH2)7CH=CHCH2CH=CH(CH2)2CH3 or
R = (CH2)7CH=CHCH2CH=CHCH=CHCH3 or
R = (CH2)7CH=CHCH2CH=CHCH2CH=CH2
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The basic unprocessed lacquer is called raw lacquer (生漆: ki-urushi in Japanese, shengqi in Chinese). This is directly from the tree itself with some impurities filtered out. Raw lacquer has a water content of around 25% and appears in a light brown colour. This comes in a standard grade made from Chinese lacquer, which is generally used for ground layers by mixing with a powder, and a high-quality grade made from Japanese lacquer called kijomi-urushi (生正味漆) which is used for the last finishing layers.
The processed form (in which the lacquer is stirred continuously until much of the water content has evaporated) is called guangqi (光漆) in Chinese but comes under many different Japanese names depending on the variation, for example, kijiro-urushi (木地呂漆) is standard transparent lacquer sometimes used with pigments and kuroroiro-urushi (黒呂色漆) is the same but pre-mixed with iron hydroxide to produce a black coloured lacquer. Nashiji-urushi (梨子地漆) is the transparent lacquer but mixed with gamboge to create a yellow-tinged lacquer and is especially used for the sprinkled-gold technique. These lacquers are generally used for the middle layers. Japanese lacquers of this type are generally used for the top layers and are prefixed by the word jo- (上) which means 'top (layer)'.
Processed lacquers can have oil added to them to make them glossy, for example, shuai-urushi (朱合漆) is mixed with linseed oil. Other specialist lacquers include ikkake-urushi (釦漆) which is thick and used mainly for applying gold or silver leaf.
The problem with using nitrocellulose in lacquers was its high viscosity, which necessitated dilution of the product with large amounts of thinner for application, leaving only a very thin film of finish not durable enough for outdoor use. This problem was overcome by decreasing the viscosity of the polymer (the term actually post-dates the empirical solution, with Staudinger's modern structural theory explaining polymer solution viscosity by length of molecular chains not yet experimentally proven in 1920s) with heat treatments, either with 2% of mineral acid or in an autoclave at considerable pressure.
The first practical nitrocellulose enamel Glossy White S.2567, still for interior use, was introduced in 1919 in the UK by Nobel Explosives.
In 1923, General Motors' Oakland brand automobile was the first to introduce one of the new fast-drying nitrocellulose lacquers, a bright blue, produced by DuPont under their Duco tradename. In 1924 the other GM makes followed suit, and by 1925 nitrocellulose lacquers were thoroughly disrupting the traditional paint business for automobiles, appliances, furniture, musical instruments, caskets, and other products. Henry Ford and, in the UK, Herbert Austin were introducing nitrocellulose lacquers at the same time, and soon the market flourished.Nitrocellulose lacquers are also used to make firework fuses waterproof. The nitrocellulose and other resins and plasticizers are dissolved in the solvent, and each coat of lacquer dissolves some of the previous coat. These lacquers were a huge improvement over earlier automobile and furniture finishes, both in ease of application and in colour retention. The preferred method of applying quick-drying lacquers is by spraying, and the development of nitrocellulose lacquers led to the first extensive use of spray guns. Nitrocellulose lacquers produce a hard yet flexible, durable finish that can be polished to a high sheen. Drawbacks of these lacquers include the hazardous nature of the solvent, which is flammable and toxic, and the hazards of nitrocellulose in the manufacturing process. The lacquer grade of soluble nitrocellulose is closely related to the more highly nitrated form which is used to make explosives. They become relatively non-toxic after approximately a month since, at this point, the lacquer has evaporated most of the solvents used in its production.
One drawback of water-based lacquer is that it has a tendency to be highly reactive to other fresh finishes such as quick-dry primer (excluding waterborne lacquer primers), caulking and even some paints that have a paint/primer aspect. Tannin bleed-through can also be an issue, depending on the brand of lacquer used. Once it happens, there is no easy fix as the lacquer is so reactive to other products.
Water-based lacquer used for wood finishing is also not rated for exterior wear, unless otherwise specified.
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