Variations in clean wool colour following different cleaning and processing procedures: A dissertation in part fulfilment of the requirements for the Bachelor of Agricultural Science (Honours) degree at Lincoln College

Abstract

Corriedale midside fleece samples (n = 44) were collected in November. Greasy colour was assessed and susceptibility to discolouration determined by incubation. Tristimulus values were measured after cleaning by 3 procedures:4 bowl laboratory rake scouring, commercial minibowl scouring or preparation by the standard procedure for presale colour measurement. Samples from each cleaning method were heated (at 105°c for 15 minutes) or heated and then reheated (at 105°c for 30 minutes) or blank dyed, and tristimulus values measured. Tristimulus values after blank dyeing were predicted using a computer simulation model. Wools scoured commercially were significantly more discoloured than wools scoured in the laboratory or prepared by the standard procedure. Wools scoured in the laboratory had significantly higher Y-Z values than wools prepared by the standard procedure. Greasy colour and susceptibility to discolouration were significantly correlated (0.453). Greasy colour and the susceptibility to discolouration were poor predictors of subsequent processing colour. The correlations between wools scoured commercially and wools cleaned by the standard procedure were 0.662, 0.627 and 0.753 for Y, Z and Y-Z values respectively. The correlations between Y-Z values after cleaning and Y-Z values after heating, reheating or blank dyeing respectively were 0.738, 0.749 and 0.826 for laboratory scoured wools and 0.814, 0.458 and 0.475 for commercially wools. The predicted Y and Z values after blank dyeing were poorly correlated to the actual values measured after blank dyeing.