ABSTRACT
Abstract: Acid dyes are anionic, soluble in water and are essentially applied from acidic bath. These dyes are applied on wool, silk and nylon when ionic bond is established between protonised –NH2 group of fibre and acid group of dye. Overall wash fastness is poor although light fastness is quite good. As dye and fibre contain opposite electrical nature, strike rate and uptake of acid dye on these fibres is faster; electrolyte at higher concentration is added to retard dye uptake and to form levelled shades. Acid generates cation on fibre and temperature helps to substitute negative part of acid with anionic dye molecules.
