The woolgrower, when the proper season of the year has arrived, gathers his flocks for shearing. The time varies in different climates, but is in the spring when the sheep no longer needs its wool for warmth. Different practices are employed in shearing; sometimes the sheep are washed in a running stream and then shut in a pen until they are thoroughly dried, or turned onto clean grass or straw, but more often they are not washed at all. The manufacturer often prefers unwashed pelts, because washing removes the suint; and unless the sheep are allowed to run long enough after the process to excrete more of this substance, the wool becomes harsh. There is also danger of felting the wool if there is any rubbing; therefore washing in running water is better than any other, since it carries off the dirt more easily and provides a constant supply of clear water.
Shearing consists in removing with shears the entire fleece of the sheep in one continuous sheet. Often the shearing is done by a machine, which gives rather better results than hand shearing, as it is more even. The pelt or fleece from each sheep is rolled into a compact bundle, and here again care must be taken that no dirt or vegetable matter is rolled up with the wool. The sheep should be sheared in a place free from straw, and no vegetable fiber cord should be used in tying the bundles, as it may become mixed with the wool and cause difficulty later. The single fleeces are combined into bags or bales and sent to market.
The first process after the wool reaches the manufacturer is opening and sorting the bales of fleeces. The task of the woolsorter is not the most pleasant. In the first place the fleeces are very dirty and odorous and, more serious still, often contain anthrax germs, which produce the disease commonly known as woolsorter's disease, with sometimes fatal results. To lessen the danger of contracting anthrax the best factories provide screens on the top of a duct, through which air is sucked. The expert woolsorter unrolls his fleece on top of this screen. The dust and germs are drawn down together as he rapidly separates the wool into the different grades, putting each grade into a basket provided for it.
The wool must next be freed from the large percentage of different impurities present. Dirt and animal matter from the ground, vegetable matter, burrs, leaves, sticks, etc., and the various excretions of the skin of the sheep are matted into the fleece. Several processes are necessary to remove these different impurities. First, the wool is washed. This opens the little scales of the woolen fibers, and allows them to shake apart and spread out. Hot water makes the wool harsh, so a moderate temperature must be maintained. Soap is used to remove the grease and dirt, but here again care must be used, for strong free alkali injures the wool. The alkaline carbonates seem to be best suited for scouring, as at moderate temperatures they do not appear to harm the wool.
Soft water is necessary for successful washing, and if only hard water is attainable it must be softened or have the lime precipitated by caustic soda. A soft potash soap should then be used, and in the last waters this soap should be neutral.
The wool is washed by being moved slowly through long troughs containing the water, soap, and carbonate. It is then squeezed through rollers.
The wash water contains valuable potash from the suint of the wool, and also oil and other substances, which are extracted for fertilizer and various purposes.
The wool must next be dried. Here again care must be used. Wool dried by artificial heat too rapidly is harsh. The best methods are either to lay the wool on a netting and blow heated air up through it or, better still, to dry it in a hydro-extractor, which, revolving at a high speed, forces the water out at the sides.
Carbonization is the process used to remove the vegetable impurities which do not come out in the scouring. These burrs, etc., stick so closely to the wool that the best method for removing them seems to be to destroy the vegetable matter completely by a chemical which does not harm the wool. Ordinarily the wool is saturated with dilute sulphuric acid, which is then dried. The drying process removes the water from the acid, which then takes up the water of the vegetable matter, thus disintegrating it. As the burrs, etc., then fall to pieces, a dusting process removes the pieces; the washing which the wool must undergo to remove the acid also removes the burrs.
The burring machine sometimes removes the burrs by a mechanical process, but this is not so satisfactory as carbonization.
When the wool has been washed thoroughly, dried, and carbonized, so much of the natural oil has been removed that if it is to be soft some oil must be returned before the succeeding processes are carried on. The best grades of oil are used for wool to be made into worsted yarns, as the oil remains in them longer; in woolen, however, it is all washed out in the milling processes; therefore cheaper oils may be used. The wool has now been converted from a dirty, oily, compact mass into a loose, fluffy, white pile, with comparatively little impurity, although still much tangled. The next step must be to convert this tangled mass into even, fine threads. Here the process is divided, first, into the making of woolen yarn; second, into the making of worsted yarn.