Great care must always be taken, in wool dyeing, to preserve the lustre and the soft effect of the wool, and to avoid felting. This can best be done by using moderate amounts of acid, by dyeing at moderate temperature and never raising the dye-bath quite to the boil; and finally, by handling the goods as little as possible in the acid dye-bath, consistent of course with exposing every portion equally to the action of the dyestuff. Cotton skeins can be worked and rubbed, and pulled, and thrown up and down in the hot dye-bath, without fear of injuring them. But wool should be handled carefully, and worked in the dye-pot quietly and gently, just sufficiently to accomplish two results. First, the wool at the bottom of the pot should be raised by a lifting and turning motion and replaced by fresh material; and second, when the wool is lowered back into the liquor it should be loosened, so as to allow the dye-liquor to penetrate the mass. CHAPTER IX DYEING FEATHERS The use of feathers and, especially, of ostrich feathers for millinery has, during the past few years, increased to enormous proportions. Besides the home product, from California and the Western States, which, however, is but small, the importation of raw feathers from abroad has averaged, during the past two or three years, nearly eight millions of dollars. As yet, the dyeing of these feathers is almost entirely confined to professionals—their processes, although simple, not being generally known or published. As before mentioned, feathers, like other animal products, can be colored with ease by either the Basic or the Acid dyestuffs. In practice, as with wool and silk, the Acid dyes are universally used, because of their greater variety, their greater fastness to light, and their better levelling properties. To use the Acid colors with success the following points must be carefully considered. First, the baths must be such as not to ruin or “burn” the feathers, i.e., they must leave intact the tiny barbules upon the barbs or “flues,” as the dyers call them, which make the feather look soft and full and not stringy. Second, the quill must be fully dyed, and the shaft, or stem of the feather, must also be colored just as well as the flues. This is a very common defect in feather dyeing. The quill, being hard and stiff and horny, is much more difficult to penetrate with the dyestuff than the soft, delicate fibres. If the feather, therefore, is dyed hurriedly or carelessly, the latter may be colored dark and full, long before the quill or the lower part of the stem has been dyed at all. This necessitates painting the stem after the finishing process, with oil colors, to match the rest of the feather. Finally, after dyeing, the feather must be properly finished so that the flues will not look woolly on the one hand, nor stringy on the other hand, but soft and full.