Reactive dyes are the main group of dyes used in the textile industry. They are very effective in fabric dyeing due to the reactive groups capable of forming covalent bond with a hydroxyl or amino group on the fiber. Reactive dyes with the bright color, good level dyeing, good fastness to wet processing, complete chromatography, and the application of the convenience and lower cost, etc., are widely used in cotton, linen, rayon, silk, wool fibers and its blended fabric dyeing and printing.

Vat dyes are one of the most important dyes for dyeing and printing on cotton and cellulosic fibers. They have excellent all-round fastness, which includes-washing, light, perspiration, chlorine and rubbing fastnesses. Vat dyes are insoluble in water and have to be dissolved in water by using sodium hydroxide and sodium Hydrosulphite. The dyes are applied in a soluble, reduced form to impregnate the fiber and then oxidized in the fiber back to its original insoluble form.