The operation of leveling the nap on cloth is much used in the woolen and worsted trades, as well as in the case of certain cotton fabrics. Shearing regulates the height of the nap or protruding fibers found on the surface of goods. The machine used may have one or two shear blades or more. A blade is exceedingly short in order to shave, shear, or cut off the undesirable portions. It can be arranged or set to leave a certain height of even, uniform nap on goods, since the blade can be
raised or lowered, as desired. The blade is regulated to the thirty·second part of an inch. Thus, a nap could be 4/32 or 6/32 of an inch in height.
The blades are on the principle of those on a lawn mower. The material to be sheared passes under the blade and all fibers longer than the setting of the blade are taken off neatly and cleanly. There remains an evened—off surface on the fabric that leaves a sort of pile effect.
Goods may be run through the shear any number of times to produce a good surface. The operator has to be on guard constantly to watch for knots, loops, or other parts of the cloth that may be cut, and thereby rip a goodly portion of the material. When these raised places come around to the blade, the shearer raises the blade to admit the passage of the cloth underneath. These blemishes are later cared for by the menders and sewers before the cut is finally passed.