The dyeing of supermicrofibre nylon with acid and vat dyes

5% omf dyeings of three 1:2 pre-metallised acid dyes displayed poor fastness to repeated washing at 60 °C on 0.05 dtex ‘supermicrofibre’ artificial nylon suede. Although fastness was improved by an aftertreatment with the full backtan, considerable dye loss still occurred during repeated washing, which was attributed to the large surface area of the microfibre substrate. In contrast, the wash fastness of 4% omf dyeings of three vat dyes, applied as both the alkali leuco and acid leuco variants, was substantially better than that of the acid dyes, despite the considerably higher colour strength of the vat dyeings. Although the rub fastness of the vat dyeings was higher than that of the acid dyeings, the level of rub fastness, especially wet, was only moderate. The colour and colour strength of the acid leuco dyeings were generally different to those of the alkali leuco dyeings.