The wash-off of dyeings using interstitial water part 2: Bis(aminochlorotriazine) reactive dyes on cotton

2% omf dyeings of three, bis(aminochlorotriazine) reactive dyes on cotton were washed-off using a five-stage process recommended by the dye maker and a novel method that utilised two water rinses and treatment with damp nylon beads. Whilst similar levels of fastness were obtained using four temperatures in the final water rinse stage (ie cold (ambient), 50 °C, 70 °C and 98 °C) of the bead wash-off processes, a final rinse in water at 98 °C imparted levels of staining that were similar to those achieved using the five-stage wash-off process. The depths of shade and colour of the dyeings achieved using the bead wash-off methods were very similar to those obtained for the recommended process. When 5% omf dyeings were washed-off using a bead process that employed a commercial wash-off auxiliary and a cold water final rinse stage, levels of staining and shade change were obtained that were comparable to those secured using a recommended, six-stage, recommended wash-off process. As the beads adsorbed a sizeable amount of vagrant dye that was removed during wash-off, the various bead wash-off processes generated either only one or two coloured rinse liquors compared to the five or six coloured rinse liquors that ensued from the standard wash-off process, thereby constituting a lower effluent load.

► Novel wash-off using two water rinses and treatment with damp nylon beads.
► For 2% omf dyeings, a final rinse in water at 98 °C gives similar wash fastness as a five-stage standard wash-off.
► For 5% omf dyeing, wash-off using beads and auxiliary with a cold water final rinse gives similar fastness as a six-stage, standard wash-off.
► Beads adsorb a large amount of vagrant dye removed during wash-off so less coloured rinse liquor produced.
► Bead wash-off consumes less energy and water than standard wash-off.