Super-black Wool Dyeing with Reactive Dyes

Environmental scrutiny of textiles is increasing as customers become more conscious of what treatments are done to their clothing. Each step of textile processing should have a minimal impact on the environment. Dyeing of super-black shades on wool has traditionally been done using chromium dyes. Chromium in effluent can have a major toxicological impact on the environment. Wool reactive dyes offer an alternative to chromium dyes in achieving super-black shades on wool. This work aimed to increase the knowledge of wool reactive black dyes on chlorinated and unchlorinated wool. Colour strength of wool dyed with reactive dyes was inferior to dyed with chrome dyes with regards to super-black colour. It was found that there were different dyeing behaviours between chlorinated and untreated wool fabrics when dyeing with two black reactive dyes - Lanasol NSC and Lanasol CE-PV. Dye exhaustion was investigated by imaging the cross-section of the wool fibre during different stages of the dyeing process and determining the total dye absorption spectrophotometrically. The total amount of dyes exhausted was lower on chlorinated fabric than that on untreated wool fabric. The temperature of dye migration into the fibre was found to be higher than for normal reactive dyes. It was found that 80�C was a more suitable temperature to hold at to allow for controlled migration of the dye into the fibre. The wash, rub and tensile strength were all found to be the same as or better than chromium dyed fabric. In order to improve the exhaustion on chlorinated wool fabrics, sodium bisulphite and urea were trialled before and after the application of dyes. No obvious positive results were obtained by the usage of those two chemicals during the dyeing process.<p></p>