The dyeing of silk part 2: Aftertreatment with natural and synthetic tanning agents

Moderate/deep shades on silk were produced using three non-metallised and two pre-metallised acid dyes. Three aftertreatments, namely a syntan, syntan + cation and modified full back tan, improved the fastness of the dyeings to repeated wash testing at 40 °C. However, the extent of this improvement varied for the dyes used. For the two pre-metallised acid dyes and one non-metallised acid dye, the modified full backtan gave marginally superior results whereas for the remaining non-metallised acid dyes, there was little difference in the magnitude of the improvement imparted by the three aftertreatments. In terms of the depth of shade obtained at the end of the five wash tests, the modified backtan gave markedly paler dyeings in the case of the three non-metallised dyes used whilst similar depths of shade were obtained in the case of the two pre-metallised acid dyes, irrespective of aftertreatment used. The aftertreatments also varied in terms of their effects on the hue and chroma of the dyeings, with the modified full backtan generally imparting greatest colour change.