Wool, as it is shorn from the sheep, is known as grease wool. The first step in the manufacturing of wool is scouring, or removal of all grease and foreign matter. Within any given grade, as determined by length of staple and fineness of fiber, the yield of clean wool is the primary factor in determining the value of the original grease wool. The price of scoured or clean wool is multiplied by the percentage yield of clean wool to determine the value of the grease wool.
Esplin, Alma C.; Phillips, Ralph W.; and Madsen, Milton A., "Bulletin No. 298 - Wool Scouring Tests in Utah" (1941). UAES Bulletins. Paper 260.