Acid Blue 25  Acid Blue 25 (C20H13N2NaO5S) is an acid dye that is water-soluble and anionic and used for adsorption researches. The structure is an anthraquinone. Acid Blue 25 is powder-like and poorly soluble in water. The dye is soluble in solvents such as acetone and ethanol. Acid Blue 25 is used for dyeing wool, silk and mixed fabric and printing them in a direct method. The dye is extensively utilized to color leather, paper, cellulose, and PC blends during the manufacturing process.