Reducing Pigmented Fibres in White Wool

The presence of dark fibres in white wool results in reduced profits or in cost recovery claims by wool processors and in reduced confidence in wool as an apparel fibre, which ultimately means lower prices for greasy wool. The allowances set by fabric manufacturers for contaminants are extremely small, typically no more than 3 contaminant faults per garment or per running metre of fabric, while spinners set limits of about 100 dark fibres per kg of top to guard against claims involving white and pastel fabrics and garments (Foulds 1988). Although dark fibres in wool are usually urine stained or melanin pigmented they can sporadically be of non-sheep origin, such as fodder bale twine which can render a top almost worthless (G. H. Michell & Sons Pty Ltd pers. comm.).