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makes nylon of great value in the manufacture of hosiery. Elasticity is achieved by drawing the yarn to some four to seven times its original length, it becoming truly elastic, with the result that if stretched further, it springs back to the length it originally was before it assumed the property of true elasticity. Tensile strength factor is brought about by the long, “oriented” molecules (10 to 12 millionths of an inch long) lying close together, and giving rise to powerful inter-molecular forces which resist slipping of the molecules when tension is applied. The breaking of the yarn, or fabric, is due only to separation by force of the parallel molecules, so breaking down the great resistance to separation which is created by the extreme length of the molecular chain in the nylon filament. It is this combined strength-elasticity factor of drawn nylon which causes the yarn to lend itself so well to the manufacture of fine gauge hose. Until the development of nylon yarn, silk was the only textile fibre which possessed the strength-elasticity demanded of a stocking yarn, in contrast to rayon, which can be made strong enough for use in hosiery, but which lacks the elasticity necessary if a stocking is to hold its shape after being stretched.

The question now arises, “Will nylon hosiery outlast Silk Hose”? Here, the weight, grade, and the quality of the workmanship entering into the manufacture of the hosiery are interdependent, but assuming all these factors to be equal, stockings made from nylon, because of its superior strength-elasticity property, wear at least as long as other high-quality hosiery of the same construction. In the yarns of the future, therefore, nylon offers a serious challenge to silk.

THE PROPERTIES OF NYLON

Wonderful claims are made for stockings manufactured from nylon, this providing a sheerness with reasonable strength far ahead of that found in any other sheer type of hosiery available at the present time. Nylon has also a good clinging quality, and a splendid elastic property, this property of elasticity persisting whether the hose be wet or dry.

Toughness. Oriented nylon is extremely tough. (While the term, “toughness” is not easy to define, a material is said to be

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characteristics—is that derived from Phenol, this being combined with a diamine likewise derived from Phenol. Oxygen from the air is also needed in making the dibasic acid, ammonia being used in making the diamine, and since Phenol is obtained from bituminous coal, and ammonia is made synthetically by causing the hydrogen from water to unite with nitrogen from the air. It follows that this particular nylon is derivable basically from coal, air and water—and coal, of course, this country has in abundance. Although these materials are “dirt cheap”, we must appreciate that in order to make nylon, many intricate reactions are involved, and elaborate and costly equipment is necessary, with rigid control at every step. Since nylon is not produced chemically from cellulose, nor does it have a cellulose base, it follows that nylon cannot be considered as a type of rayon or synthetic silk.

HOW NYLON IS MADE

Spinning the yarn. The nylon in molten form is forced out through a spinneret by a suitable pump. As soon as the filaments meet the cool air outside the spinneret, they instantly freeze, that is, become solid. The filaments from one spinneret are wound up on a suitable device, and later are given a twist of a few turns per inch to facilitate further handling.

How size of yarn is controlled. The size of individual nylon filaments is determined by controlling the rate of delivery from the pump, and by the rate at which yarn is drawn away from the spinneret. The size of the final yarn, before drawing, is determined by the size and number of the individual filaments in the yarn forced through the holes in the spinneret.

Elasticity and tensile strength. Nylon has a very important property, in that when cold, the yarn can be stretched by unwinding from one spool on to another at a rate based on the theory that if a four-fold stretch is required, this is accomplished by winding up the yarn at a rate four times that at which it is unwound. During this stretching operation, the long chain-like molecules take on an orderly arrangement, becoming parallel to one another, and lying closer together. This molecule behaviour is known as “orientation”, and it is this property that