IMPROVED DYEING WITH REDOX SYSTEMS .3. DYEING COTTON AND VISCOSE WITH DIRECT DYES

The dyeing properties of cotton and viscose fabrics with a direct dye, namely,direct Fast Orange S, in the absence and presence of some redox systems were investigated under different conditions. It was found that the color strength is much greater in the presence than in the absence of the redox system. Besides, dyeings obtained in the presence of the redox system retain more of their color strength after DMF extraction than dyeings obtained in the absence of the redox system. These findings suggest that in the presence of a redox system, dyeing involves covalent bonds, between cellulose and dye by a free radical mechanism in addition to their conventional attachment via physical forces.