The first step in the manufacture of woolen items is the shearing of wool from sheep, a practice that often varies in the way it is carried out. In some countries, for instance, all wool from a single sheep is shorn at once, while in other areas different grades of wool are removed separately. The latter methodology makes the following step, the grading and sorting of the wool, a simpler, more expedient process. After sorting, sheep wool undergoes scouring, a washing process that removes grease, perspiration, and debris from the fibers. When dried, the scoured wool is usually carded and combed before the processes of roving and spinning are begun. Once yarn has been spun from the wool, it is ready for knitting or weaving, but the cloth it is used to produce may also be subjected to a number of procedures in order to generate specific characteristics, such as waterproofing and shrink resistance.