Artificial Silk

New Zealand Tablet, Volume XXXV, Issue 19, 9 May 1907, Page 15

Artificial Silk

A textile fibre which has recently come into the market is artificial silk. This is a French development which is yet scarcely on its feet, but promises a great future. The present output is about one-eighth that of annual silk, or about 4UOO tons per annum. The selling price is about 14s per" pound, as against 18s for animal silk. The centre of the new industry is in France, but there are also factories in Belgium, Switzerland, Germany, Spain, and Italy. - Artificial silt is produced from the vegetable compound cellulose, which substance is also the basis of silk-worm silk. The raw material from which artificial silk is produced is chiefly cotton fibre, though paper and wood pulp can also be used. The lowest grades of cotton pan be used for this purpose. The cotton 1 or puilp is first cleansed and. b-leacjhed by chloride of lime. It is next soaked in a mixture of three parts sulphuric acid and two parts nitric acid. The temperature of the acid bath must be held between 85deg. F. a nfl lOOdeg. F. This treatment is called nitrating, and has for "its end to rende: the cellulose soluble in a mixture of alcohol and ether. A bath of some drying oil, such as cotton seed or castor oil, is used after the nitrating bath,. The solution thus produced is a syrup-like liquid which is run into a closed tank, and subjected to a pressure of several atmospheres. This tan'c has at the bottom a number of glass tubes having a diameter o£ about l-150inch, and any convenient length. The outlets of the tuibtes dip in,to or overhang a basin of cold water. Through these capillary tubes, by the air 'pressure in tank, the liquid, now called pyroxylin, is forced in fine streams, which coagulate and barden'immiediaitely they touch the water. From the water bath the naw solid threads are wound on spools, and passed through a heated an 4 ventilated chamber. The hot air in the chamber vaporizes, and drives off the alcohol from the th-eads. By suitable tubes this alcohol is carried to a condenser, where it is recovered and used over again. The dried threads are very combustible, and are next treated 'to a bath of sulphydrate of ammonia o~ potassium arjd then washed in cold water. They are now become no more inflammable than ordinary smin cotton. The fibre is then ready to be spun into cables of any desired' diameter. The resulting thread is very toiugh, and more lustrous than^andmal silk. The special uses of artificial silk, and for which it is superior to animal silk, is in lace making and for weaving fajbrics in' which the pattern stands in high relief. Such poods are tapestries, upholstery, and brocades. Thf* fabrics are as durable as an^ animal silks. This fibre is also the best known material for maling; incandescent mantles for gas burners. Mantles of a*ti- ■ ficial silk, when impregnated with saHs of thorium ard cerium, give the best possible light, and last about six times as* long as ordinary mantles. Artificial silk filfeiments, when carbonised, meike excellent ' car Lions ' for incandescent electric lights. The filaments when treated with shellac and easier- oil are used for making tobth brushes. Cloth t made from artificial silk can be 'bleached white, and fast-Hyed with red, blue, violet, saffron,- or black dyes p-f t&e, aniline group.