Improvements in the Dyeing of Wool at Low Temperatures by the Use of Amine or Ammonia Pretreatments

Pretreatments of wool with strong solutions of amines and ammonia have been reported to increase dye adsorption rates in many cases. The effect has been ascribed to the formation of beta-aminoalanine residues in the wool with a resultant increase in its electrical potential. The effect of more dilute solutions of ammonia and dimethylamine is reported here. The possibility that the amines act simply as alkaline hydrolysis promoters has been examined by taking into account internal pH effects. The addition of salt to the amine treatment solution has been shown to be very advantageous so that ‘low-temperature-dyeing’ wool may be readily prepared by a simple ammonia-salt pretreatment