This category of the textile industry includes mills such as wool scouring, top making and general raw wool cleaning. Raw wool must be cleaned by wet processes before the fibre can be dry processed to produce yarn or fabric. Neither cotton nor synthetic fibres require this initial wet cleaning before processing. Scouring begins with sorting the fleece and feeding it to a hopper. The wool is then carried through a series of scouring bowls where scour liquor flows counter-current to it. Detergent is added in the third and fourth bowls to emulsify the grease and oils. The scoured wool is then dried. In mills where the cleaned wool is converted into wool top, the wool is combed and gilled. The products are short fibres (used for wool yarn) and long fibres (used for wool top). Figure 2 shows the manufacturing processes of a wool scouring mill .