Lacquer

The term lacquer is used for a number of hard and potentially shiny finishes applied to materials such as wood. These fall into a number of very different groups. The term lacquer is used for a number of hard and potentially shiny finishes applied to materials such as wood. These fall into a number of very different groups. The term lacquer originates from the Sanskrit word lākshā (लाक्षा) representing the number 100,000, which was used for both the lac insect (because of their enormous number) and the scarlet resinous secretion, rich in shellac, that it produces that was used as wood finish in ancient India and neighbouring areas. 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 to feel and look at. Asian lacquer is sometimes painted with pictures, inlaid with shell and other materials, or carved, as well as dusted with gold and given other further decorative treatments. In modern techniques, lacquer means a range of clear or coloured wood finishes that dry by solvent evaporation or a curing process that produces a hard, durable finish. The finish can be of any sheen level from ultra matte to high gloss, and it can be further polished as required. It is also used for 'lacquer paint', which is a paint that typically dries better on a hard and smooth surface. In terms of modern products for coating finishes, lac-based finishes are likely to be referred to as shellac, while lacquer often refers to other polymers dissolved in volatile organic compounds (VOCs), such as nitrocellulose, and later acrylic compounds dissolved in lacquer thinner, a mixture of several solvents typically containing butyl acetate and xylene or toluene. Lacquer is more durable than shellac. The English lacquer is from the archaic French word lacre 'a kind of sealing wax', from Portuguese lacre, itself an unexplained variant of Medieval Latin lacca 'resinous substance' from Arabic lakk, from Persian lak, from Hindi lakh (Prakrit lakkha). These ultimately derive from Sanskrit lākshā (लाक्षा), which was used for both the Lac insect and the scarlet resinous secretion it produces that was used as wood finish. Lac resin was once imported in sizeable quantity into Europe from India along with Eastern woods. Lacquer sheen is a measurement of the shine for a given lacquer. Different manufacturers have their own names and standards for their sheen. The most common names from least shiny to most shiny are: flat, matte, egg shell, satin, semi-gloss, and gloss (high). In India the insect lac, or shellac was used since ancient times. Shellac is the secretion of the lac bug (Tachardia lacca Kerr. or Laccifer lacca). It is used for the production of a red dye and pigment (red lake), and for the production of different grades of shellac, used in surface coating. Urushiol-based lacquers differ from most others, being slow-drying, and set by oxidation and polymerization, rather than by evaporation alone. In order for it to set properly it requires a humid and warm environment. 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. These lacquers produce very hard, durable finishes that are both beautiful and very resistant to damage by water, acid, alkali or abrasion. The active ingredient of the resin is urushiol, a mixture of various phenols suspended in water, plus a few proteins. The resin is derived from trees indigenous to East Asia, like lacquer tree Toxicodendron vernicifluum, and wax tree Toxicodendron succedaneum. The fresh resin from the T. vernicifluum trees causes urushiol-induced contact dermatitis and great care is required in its use. The Chinese treated the allergic reaction with crushed shellfish, which supposedly prevents lacquer from drying properly. Lacquer skills became very highly developed in Asia, and many highly decorated pieces were produced.