英文科學(xué)讀本 第五冊(cè)·Lesson 59 Wool—Its Manufacture

Lesson 59 Wool—Its Manufacture

Our examination of the different coverings of animals has shown us that Nature not only provides each creature with a suitable coat, but arranges also for an increased growth of that coat during the inclement season of the year. The sheep's coat is no exception to the rule; it is at its thickest and best during the winter. Like all other creatures, however, it would begin to lose its coat, by a natural shedding of the wool, on the return of warm weather. Instead of leaving the wool, therefore, to fall out during the summer, the farmer cuts it off each spring. With him the sheep-shearing season is always a busy one, as the work must be done at the proper time, and will admit of no delay. Think what it must be to the Australian farmer. A single "squatter's" run in Australia is frequently many miles in extent, and the sheep on it are numbered by hundreds of thousands. Not only the quality of the wool, but the health of the sheep themselves, would be affected by delay in the shearing, and consequently there is great demand for men to do the work.

The shearing process is practically the same everywhere. The sheep are first driven into a shallow pond, and well washed, after which they are allowed to run about in the sunny fields to dry. The shearer then cuts away the wool with a large pair of shears, shearing upwards from the under parts of the body, to the sides, neck, and back.

All the wool from one sheep is called a fleece. The wool from different parts of the fleece varies much in quality— that from the breast, neck, and back being the best, that from the hinder parts the least valuable.

The raw wool is very greasy and very dirty; hence the first business in preparing it for the manufacturer is to thoroughly cleanse it. This is done by boiling it in great coppers, with plenty of soap to dissolve and separate the grease and dirt.

When this is done, the wool is usually dyed the required color, and then the fibers are torn asunder by means of revolving iron spikes, until they form a loose, fluffy down.

If we examine a piece of flannel or some other worsted fabric, we find it an easy matter to separate the material, thread by thread, just as we did the calico and linen. It is just as easy to untwist the threads themselves, and if we did this, we should find that the fabric is made by practically the same processes of spinning and weaving, as those with which we have already become familiar.

There is one material difference, however, in the treatment of the two sorts of wool. The short-staple, wavy, serrated wool is sometimes known as carding-wool; the long-staple as combing-wool.

In the combing process the long, loose fibers are merely drawn out and arranged side by side, as in the combing of cotton fibers. In the carding of the short-staple wool, care is taken to arrange the fibers side by side, in such a way that the ends of some and the roots of others lie together, and the teeth or serrations point in contrary directions. The result of this arrangement is that, when such threads are twisted to form yarn, the serrations catch one in the other, and prevent them from untwisting. The spinning and weaving processes are the same for woollen as for worsted goods, but when a worsted fabric leaves the loom, it is quite finished and ready for use. Not so the piece of cloth.

If we compare a piece of flannel with a piece of broadcloth, we find the warp and woof threads, which are so plain in the former, cannot be seen in the latter; the surface is a smooth, close, and glossy nap. This difference is brought about by the process of fulling or felting. In this process the cloth is folded and beaten with large, heavy hammers for many hours—even days. This causes the fibres of the wool to felt or mat together, so that the cross threads of warp and woof are no longer visible, the little serrations on the fibers being the real cause of the felting.

Of course, this folding and beating of the woven material tends to thicken it considerably, and at the same time makes it shrink, both in length and breadth.

After fulling, the nap of the cloth is raised in a curious way. A great number of the flower-heads (seed-vessels) of the teasel, a plant something like a thistle, are fixed to a large, broad wheel, which is made to pass very rapidly over the cloth, so that the teasels sweep its surface continually. The teasels are covered with little elastic hooks, and these, as they sweep over the cloth, catch up the loose fibers of the wool, and make them stand as a nap. This raised nap is then made smooth and level by means of shears, after which all that remains to be done is to damp, brush, and press it, so as to give it a soft, smooth, glossy surface.