Acid Dyes is is a type of dye that is applied from an acidic solution. In the home or art studio, the acid used in the dyebath is often vinegar (acetic acid) or citric acid. In textiles, acid dyes are effective on protein fibers particularly animal hair fibers such as wool, alpaca, and mohair. Acid dyes are generally divided into three classes which depend on fastness requirements, level dyeing properties and economy. The classes overlap and generally depend on type of fiber to be colored as well as the process used.