To Tell Artificial Silks.

Kaipara and Waitemata Echo, 19 June 1914, Page 2

To Tell Artificial Silks.

Artificial silk is fast coming to be a very important textile material, and is being used in ever-increasing quantities by the trade. It is employed as an adjunct not only to the silk industry itself but is also being used in connection with wool and cotton in the preparation of a great variety of fabrics. It is even being used largely in knot goods and hosiery, in combination with cotton and mercerised cotton. The dyer therefore is meeting more and more with this product, and as there are three different kinds of artificial silks in general use, and as these different varieties possess certain differences in structure and quality, ft really becomes a question of considerable importance to the dyer to know one variety from another. This is more especially important because one silk may stand a treatment which would be fatal to another. The three artificial silks now to be met with on the market are described in the "Wool and Cotton Reporter" as follows :— 1. Collodion silk, known as Chardonnet, or nitrosiik. It is prepared from nitrated cotton. 2. Cuperate silk, known as Glanzstoff, Pault Elberfeld silk. It is prepared from a solution of cellulose in cuprammonium solution. 3. Viscose silk. This is prepared from a solution of cellulose in a mixture of caustic soda and carbon bisulphide. In their outward appearance the three forms of artificial silk are so nearly alike "that it would not be possible to distinguish between them. Even a microscopic examination by an experienced observer does not lead to any positive conclusion as to the kind of silk. A fairly simple test, however, according to "Paper," and one which may be easily carried out by the average dyer, is the following : A sample of the silk to be tested is I placed in a small porcelain dish and concentrated sulphuric acid is poured over the fibres. If the sample consists of a collodion silk no colouration appears until about an hour has elapsed, when the acid solution will acquire a pale yellow colour. In the case of cuprate silk the acid becomes yellow immediately. In viscose silk the acid immediately develops a reddish brown, deepening to a rusty brown.—"Chemical Engineer."