Improvement in Wash Fastness of Dyed Silk by Aftertreatment with Commercial Syntan/Metal Salts

Silk yarns were dyed by using commercial basic, reactive and pre-metallised acid dyes. An aftertreatment with a commercial synthetic tanning agent (syntan) was applied to the dyeings and the aftertreated dyeings were further treated with metal salts in an attempt to improve wash fastness properties. When all samples (untreated, syntanned and syntanned/ backtanned speciments) were subjected five times to a repeated wash testing (ISO 105CO1), it was found that the fastness, to repeated wash testing, was improved, as expected by an aftertreatment with the commercial syntan. Further, significant, the two-stage, syntan/metal salts aftertreatment raised the level of wash fastness of the syntanned samples.