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RAYON


THE HISTORY OF ARTIFICIAL SILK


In 1734, a great French naturalist, Reaumur, said: “Silk is only a liquid gum which has been dried. Could we not make silk ourselves from gum and resin?” Nothing practical, however, was done until 1883, and it was done by an Englishman, Joseph Wilson Swan. He took out a patent for squeezing a mixture of wood and cotton pulp through small holes and thus produced threads. He did more than that; he actually made artificial silk woven goods and showed them at the Inventions Exhibition in London, in 1885.

Although Swan was the first person to produce artificial silk filaments, the experiments of John Mercer, who invented the mercerising process of cotton yarns, should be borne in mind. He found that, if caustic soda was filtered through cotton, the cotton became semi-transparent, contracted and thickened. Its strength was increased to that of linen, and the filaments became round instead of flat which consequently made it glossier. Although Mercer is not usually associated with the invention of artificial silk, he deserves some of the credit; for the use of caustic soda is one of the important stages in the production of artificial silk. It was Mercer who discovered the remarkable solvent effect caustic soda has on many organic substances, both animal and vegetable. The year later a Frenchman, Count Cardonnet, experimented with the production of artificial silk. In the same year, 1884, he opened the first factory at Besancon. He may be considered, therefore, the founder of the artificial silk industry. His process involved the production of artificial silk by the nitro-cellulose process. Today that process has gone out of use almost entirely.

The aim of Swan’s original experiments was to make a filament for incandescent lamps. He succeeded in that, and then made a finer filament for textile purposes.

Swan’s laboratory was at Bromley in Kent. This laboratory became the headquarters of a group of chemists and inventors.

STOCKINGS

Rayon and nylon are twisted according to the type of stocking the manufacturer wishes to produce.

Silk, rayon and nylon can be over-twisted, in which case the elasticity of the stocking will suffer, while on the other hand it can be under-twisted to save money.

The twist of fibres used in the manufacture of a pair of stockings has a direct bearing upon the price, because the more twist put into a yarn, the more yarn is used, and the cost of twisting increases in proportion to the number per inch, and the construction of the final yarn.

Each arrangement of twist is dyed an identifying distinctive tint (this dye is fugitive, and washes away) and the yarn for hosiery purposes is wound on to cones for knitting.

The cones being received in the knitting mill, some are taken direct to the knitting machines, where the humidity is controlled and the room temperature 75 degrees 365 days every year, while other types are placed in special conditioning chambers which keep the yarn fresh and moist until required.

The following percentage relative humidities are recommended:-

 SilkCottonNylon 
Knitting656550
 AcetateRayons
Cupram.
Viscose
Knitting556565