THE ROMANCE OF SILK.

New Zealand Herald, Volume LXIV, Issue 19714, 13 August 1927, Page 4 (Supplement)

THE ROMANCE OF SILK.

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Last week, the wonderful story of the the discovery of silk was told in this column. This week, you will learn how artificial silk is made, this being one of the most interesting scientific discoveries of the present generation. It seems difficult to believe that silk stockings and the soft, beautiful materials from which dresses and underclothing are ma'de, are manufactured from wood, and yet such is actually the case. No longer are the humble little silkworms of China responsible for these beautiful materials. Whole forests are now required tp provide the world with its silk. For it is from trees that artificial silk is made. Fourfifths of the artificial silk on the world's markets is obtained from wood-pulp, the remainder originating from cotton. In both cases, however, the

processes through which the cellulose goes are the same. From the forests of Sweden, Norway, and Canada the wood pulp is exported to Britain. From the moment it reaches the textile factory until the time it becomes a dainty fabric, it is watched over and treated by the industrial chemist. This wizard does not see in his raw material some beautiful silk gown. For him it means endless dreary lines of chemical equations and lengthy calculations. On its arrival at the works the pulp, in the form of sheets, is cut up and is then immersed in a bath of caustic soda solution. It is then " mangled" and pulled to pieces by a toothed machine until a white fluffy mass results. The alkali cellulose

— """""———— en j f or a day or two, at the end of which it is sprayed with a sulphur compound, which turns | the pulp a red colour. Tho sulphurated liquid is next drawn off by suction, and the red material again given a causic bath, but of weaker strength. This completed, the substance is ground to remove any lumps, the presence of which would ruin the finished fabric.

The viscose, as it is now, is allowed to mature. It is at this stage that the critical steps have to be taken. The time allowed to age, the temperature at which it is kept, make all the difference between success and failure. Sulphur is lost during the rest, and other chemical changes occur.

The viscose is filtered and washed in the purest, . lime-free water. After this it goes into the " spinning" bath, which consists of acid and sugar. The acid converts tho red substance—boasting the formidable name of xanthogeriate—into white hydrate of cellulose, which assumes a thread-like farm. Thp lhst traces of sulphur are removed from the thread. It is bleached carefully, washed, dried, and is then ready for reeling or weaving.

From the time the pulp enters the factory till the finishing of the product no handling occurs; so sensitive is the material during some of tho stages of manufacture that tho slightest contact with a humac hand would render the fabric of inferior quality, if not useless.