Profile: Baoding Arpino Trading Co., Ltd. specializes in providing dyestuffs. Our products are widely used in leather, textile, paper and cosmetics industries. We are now engaged in manufacturing acid dyes, direct dyes, reactive dyes, disperse dyes, vat dyes and fluorescent whiteners. An acid dye is a dye, chemically a sodium (less often-ammonium) salt of a sulfuric, carboxylic or phenol organic acid. Acid dye is soluble in water and possesses affinity for amphoteric fibers while lacking direct dye's affinity for cellulose fibers. When dyeing, ionic bonding with fiber cationic sites accounts for fixation of colored anions in the dyed material. Acids are added to dyeing baths to increase the number of protonated amino-groups in fibers.