Scouring of cotton or man-made fibres to remove oils or lubricants is done at either the hank, yarn or fabric stage, prior to dyeing. This is not the case for wool, where the large quantity of impurities present means that it is always necessary to scour the fibre in its raw state. Cotton and flax scouring is usually done at high temperature using caustic liquor, whilst wool goods require a milder soap and soda, or detergent scour at low temperature. Raw wool scouring, washing and drying is usually done in a single continuous operation prior to blending.
The milling of woollen fabrics is a process, which effectively compacts the textile structure producing a change in handle from a slight to a dense matting or felting. The process is undertaken at low temperature using soap and soda or detergent. The process was originally undertaken on old open topped wooden milling machines, some of which are still in use because of their gentleness in processing and hence better fabric finish that they can provide. More modern milling machines resemble winches in shape and basic design, they may not be as gentle as the old machines, but they can be used for a wider range of processing.