Effect of Mordant Bleaching on the Optical and Mechanical Properties of Black Human Hair

Decolorisation of black human hair containing an excessive amount of melanin was carried out by alkaline peroxide bleaching under different mordanting conditions. The effect of iron mordanting methods on the optical, mechanical and tactile properties of bleached fibre was investigated. Sequestering agents, such as citric acid and oxalic acid, or reducing agents including phosphorous acid and sodium bisulphite, were employed to improve the selective absorption of iron into the fibre. The initial rate of bleaching and tactile properties were significantly affected by the amount of iron in the fibre which, in turn, was dependent on the type of mordanting auxiliary employed