Sulphur-dyed cellulosic textiles are susceptible to washing powders containing activated peracid formulations resulting in obvious fading during repeated laundering.This study presents a novel one-bath/two-stage exhaust finishing process to improve the oxidative wash fastness of CI Leuco Sulphur Black 1-dyed cotton fabric. The effect of the combined Tinofix ECO and Bayprotect Cl after-treatment was to impart better colour fastness to oxidative International Organisation for Standardisation (ISO) 105 CO9 washing of the dyed cotton compared with those dyed fabrics aftertreated with Tinofix ECO alone. In addition, while the dyed fabrics rub and light fastness performances were unchanged by the after-treatments, some improvement in the tensile strength of the combined Tinofix ECO and Bayprotect Cl after-treated fabrics was observed.

The importance of sulphur dyes are realized due to the fact that they offer an economical method of achieving dyeing of good color strength and acceptable fastness on cellulosic substrates. However, the main limitations associated with this class of dye are the lack of availability of bright colors and it’s fading on exposure to laundering with detergent and perborates/peroxides formulations. In order to meet the growing requirements of customers regarding the higher wash fastness, garment traders are in turn demanding their suppliers to achieve these properties against single and multiple washes. In this study, sulphur black 1 dyed cotton fabric has been aftertreated with Fixapret CP, Bayprotect Cl and CC (Choline Chloride) with various sequential combinations to improve the wash fastnesss of the dyed fabric against the aggressive ISO-1O5 CO9 washing system. Sequential application of Bayprotect Cl followed by CC was found to offer a significant improvement causing a 12% reduction in percentage colour loss relating to the untreated fabric, which was comparable to the independent application of Fixapret CP with minimum deleterious effects on the hue, chroma and tensile strength of the fabric.

In this study, cotton fabric and nylon fabric were dyed with a range of commercial sulphur dyes and the light and wash fastness of the coloured fabrics was investigated.The effect of after-treating the coloured cotton and nylon fabrics with a tannin-based commercial product, Bayprotect Cl, in the presence or absence of sodium sulphate in the treatment bath, was found to significantly improve the light fastness of the sulphur-dyed cotton, and the photoprotective effect was partially stable to ISO 105-C06 washing. In addition, the tannin-based after-treatment also improved the colour stability of the dyed fabrics to the perborate-based ISO 105-C06 washing. The possible mechanisms for the improved fastness properties are also discussed. The application of sulphur dyes to nylon is potentially commercially useful but has been limited because of the reported poor light fastness of the dyeings. The photoprotective effect of the tannin-based after-treatment was investigated with a view to providing the necessary commercial performance. However, it was established that on this fibre, the light fastness improvement was marginal, and the associated wash fastness to oxidative bleach-based ISO 105-C06 washing was limited.