Mordant, << MAWR duhnt, >> is a chemical that combines with dyes to prevent them from dissolving easily. The dye alone might wash out, but the compound formed by the dye and the mordant will not, so the color is long lasting. Common mordants include salts of chromium, iron, aluminum, tin, or other metals. These are basic or metallic mordants. They are used with two kinds of dyes, acid dyes and direct dyes. Tannic acid, lactic acid, and oleic acid are other common mordants. These are acid mordants, and they combine with another group of dyes called basic dyes. The compounds of basic mordants with dyes are called lakes. When alizarin, an acid dye, is mordanted with a basic aluminum salt, it colors cotton cloth a bright red, called Turkey red. See also Lake [dye] .
