Fine, short wools are sorted according to the number of counts of yarn they are expected to spin, as 48’s, 60’s, 70’s, and so on. Thus we see there are different methods of indicating qualities in different districts, and also of indicating differences of qualities between the woolen and worsted branches of the trade.
It may be noted that the quality of the wool varies in the same way as the quality of the flesh. The shoulder is finest in grain and most delicate, so the wool is finer in fiber. There is more wear and tear for the sheep at its haunches than at its shoulders, hence the wool is longer and stronger; about the neck the wool is short, to prevent the sheep from being weighted down while eating, etc.; the wool on the back becomes rough and thin, being most exposed to the rain. From the foregoing it will be readily seen that there is necessity for careful sorting, in order to insure obtaining an even running yarn, and subsequently a uniform quality of fabrics.
Wool Washing. Fleece wool as it comes into the market is either in the “grease,” that is, unwashed and with all the dirt which gathers on the surface of the greasy wool; or it is received as washed wool, the washing being done as a preliminary step to the sheep shearing. Wool, unlike cotton, cannot be worked into yarn without being thoroughly cleansed of its impurities. These impurities consist of greasy and sweaty secretions, of the nature of a lubricant to the fiber. Combined with dirt, sand, etc., which adhere to the wool, these secretions form an encrusting compound, known as yolk, which acts as a natural preservative to the wool, keeping it soft and supple. This compound, with other extraneous matter, must be removed before the wool is in a workable condition. The amount of yolk varies, the greatest amount being found in fine, short wools from the warm climates. In long-staple wool the amount of yolk is comparatively small.
WASHING ROOM
Various methods of removing these impurities have been tried; one is the use of absorbent substances, such as fossil meal, alumina, etc., to withdraw the greasy matter, so that the remaining impurities can be easily removed by washing. In other methods, naphtha or similar solvent liquids are used to dissolve the wool fats. This is followed by washing in tepid water to dissolve the potash salts, leaving the dirt to fall away when the other substances are no longer present. To work this method with safety requires a costly and intricate plant with skilled supervision. The method which is practically in universal use is washing the wool in alkaline solutions, properties of which combine with and reduce the impurities to a lathery emulsion which is easily washed off from the wool.
Great stress is laid upon the necessity of care in the washing process, as the luster may be destroyed and a brownish-yellow tint given to the wool, the spinning properties very seriously injured, the softness destroyed, or the fiber dissolved. Some wools are easy to wash, requiring little soap and a reasonable temperature; other wools are cleansed with great difficulty. A note, therefore, should be made of any particular brand or class of wool requiring special attention, to serve as a guide in the treatment of future lots. The danger lies in using unsuitable agents,—hard water, excessive temperatures, strong reagents, etc.
Caustic alkalies have a most destructive effect on wool as they eat into it and destroy its vitality. Carbonate alkalies are less severe. Whatever cleansing substances are used, it is essential that they should be free from anything that is likely to injure the wool—that they remove the impurities and still preserve all the qualities in the wool. If the washing is properly performed the alkaline portion of the yolk is removed, leaving only the colorless animal oil in the fiber. If the work is not thoroughly done the wool passes as “unmerchantable washed.” “Tub washed” is the term applied to fleeces which are broken up and washed more or less by hand. Scoured wool is tub washed with warm water and soap, and then thoroughly rinsed in cold water until nothing remains but the clean fiber.
DEGREASING PLANT—REMOVING GREASE FROM WOOL