Effects of the KMnO4/Salt Shrinkproofing Treatment on the Frictional Properties of Wool Fibers

Abstract

Following on the observation that the KMnO4/salt shrinkproofing process attacks the scales on the intrados of the crimp of wool fibers preferentially, the “static” friction of wool fibers over polished horn in aqueous media has been measured by the standard capstan method under conditions chosen to ensure that some contact is made with the intrados of the crimp. It has been found that the treatment causes a large increase in the with-scale friction and in some circumstances a decrease in the frictional difference. When the proportion of contact with the intrados of the crimp is reduced, these effects become much smaller. Both types of frictional change are the result of degradation of the material inside the scale-cells, which makes the scales, when wet, softer and less elastic than the scales of untreated fibers. Experimental conditions determine whether this softening is expressed as an increase in with-scale friction or as a decrease in the frictional difference.