In general, these artificial silks, manufactured as they are from wood pulp and other vegetable materials, are to be dyed with the Salt, Sulphur, or Vat dyes, care always being taken to expose them to the action of hot dye-liquors as short a time as possible. The Salt dyes are less apt to interfere with the brilliant lustre, but the Sulphur and Vat dyes have the great advantage of dyeing in a cold or lukewarm bath, without any loss in fastness. The Chardonnet silk has a special affinity for the Basic dyes, and in the trade is usually dyed both light and dark shades with these coloring matters, without previous mordanting, in a slightly acid bath. This practice, however, while simple and easy, is not to be recommended. For the Basic dyes, with but few exceptions, fugitive under all circumstances, are particularly sensitive to light, when dyed in light shades, upon such a brilliant and almost transparent medium as this is. On the other hand, articles made of artificial silk, being easily injured by rain, are not so liable to be exposed to the open weather as some other less delicate materials. The Viscose and Elberfeld silks (Glanzstoff) have less affinity for the Basic dyes, and dye more readily with the Salt and Sulphur colors than the Chardonnet silk, made from gun cotton. But it is perfectly possible to dye the latter also with fast colors of the Salt, Sulphur, or Vat classes, providing large amounts of dyestuff are used to bring up the shade. Indeed it is poor economy to be sparing of the coloring matter, when working with any kind of artificial silk. For speed is essential, and the dyer who lets his material remain long in the dye-bath is liable to get into difficulties. The artificial silk, after dyeing, should be finished much like natural silk, by rinsing and then passing through a bath containing some olive oil, emulsified in a weak bath of soda ash. This increases the lustre. It should also be dried at a fairly low temperature and, while drying, kept stretched out by hanging a wooden or glass rod in the loop of the hanging skein, or some similar device, taking care to avoid strain great enough to pull apart the weakened fibre. When dyeing this material great care should also be taken in tying up the individual skeins and in handling them. Turn them in the dye-bath as little as possible consistent with even dyeing. The threads, unless very tightly spun, are constantly liable to come untwisted, and the knots to untie, causing much annoyance.