Relationship between pigmented fibre in raw and processed wool when other dark fibre is controlled - a review

Abstract

This paper reviews the outcomes of processing trials that studied the relationships between both inherent and transferred pigmented fibre levels in raw wool with those found in processed top. Worsted processing of white Corriedale and Merino wool batches containing inherent isolated pigmented wool fibres produced tops with higher counts than found in the raw wool. These increases are consistent with expectations based on the known high levels of fibre breakage occurring during worsted processing. In contrast, the relatively shorter fibres arising in contamination situations involving contacts with coloured sheep have shown levels in top to be less than those found in the raw wool; apparently associated with the biased separation of these short fibres to the noil product during worsted combing. Whatever its origin if dark fibre is present in the raw wool then the risk remains that wool top and noil will as a consequence be affected. It is recommended that processors select only those wool lots that have the lowest identifiable risk (e.g. as indicated by the DMFR scheme) to satisfy orders for critical white and pastel products. These risk assessments could ultimately include Dark and Medullated fibre tests on core sample wool from sale lots for added confidence.