An organic pigment prepared when a dye has been precipitated on a powdered, colourless, inorganic substrate. The term derives from the Latin word lacca, used in the Middle Ages to denote both lake pigments and the Lac dye. Because of its transparency, aluminium hydroxide is the most commonly used substrate or carrier. Barytes, barium sulphate, provides an opaque lake pigment. Other compounds used as carriers are: chalk, clay, gypsum, tin oxide, zinc oxide, white earth, and green earth. Often a mordant, such as tannic acid, lactic acid, or sodium phosphate, is used to fix the dye to the substrate. Many of the natural dyes were made into lake pigments, such as cochineal, kermes, madder and lac for use in oil painting. In the late 19th century the chemical industry discovered synthetic equivalents of madder and indigo and went on to produce a range of new ones from coal tar derivatives. These and many of the bright new pigments introduced in the 20th century have all been manufactured as lakes. Some, such as aniline dyes, are also prepared in this manner for use as paint pigments. See also: dye. Synonyms: Lakes Museum of Fine Arts, Boston (2000); Trench (2000). [J. Cassar, R. de Angelis]