Investigation into the effect of a plant-derived stabiliser on the light and wash fastness of sulphur-dyed cotton and nylon fabrics

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.