Plying

In the textile arts, plying is a process used to create a strong, balanced yarn. It is done by taking two or more strands of yarn that each have a twist to them and putting them together. The strands are twisted together, in the direction opposite that in which they were spun. When just the right amount of twist is added, this creates a balanced yarn, one which has no tendency to twist upon itself. Almost all store-bought yarns are balanced, plied yarns. The word ply derives from the French verb plier, "to fold", from the Latin verb plico, from the ancient Greek verb πλέκω.

A two-ply is thus a yarn plied from two strands, a six-ply is one from six strands, and so on. Most commercial yarns are more than a two ply. Embroidery floss is generally a six-ply yarn, for example.

The creation of two-ply yarn requires two separate spools of singles and either a lazy kate or something to hold the spools in place. On a wheel, two-ply is created by taking two spools of singles, placing them on a lazy kate, tying the ends together onto the spool attached to the wheel, and spinning the wheel in the opposite direction to that in which the singles were spun, while also feeding the yarn onto the spool on the wheel. On a drop spindle, two-ply is created by placing the spools on a lazy kate, tying the ends together onto the drop spindle, holding equal lengths of singles together and dropping the spindle. The weight of the drop spindle combined with the twist in the singles, causes the drop spindle to turn in the opposite direction that the singles were twisted in until the two singles are plied together.

When hand-spinning, there are two common ways to ply a balanced yarn: regular and Navajo.

When spinning fleece into yarn, the fleece must be scoured and vegetable matter removed. The fleece is carded or combed and then spun into singles. These singles are used to create the finished yarn in a process known as plying. The purpose of plying singles is to strengthen them so that they do not break while knitting or crocheting them.

Most spinners (who use spinning wheels) ply from bobbins. This is easier than plying from balls because there is less chance for the yarn to become tangled and knotted if it is simply unwound from the bobbins. So that the bobbins can unwind freely, they are put in a device called a Lazy Kate, or sometimes simply kate. The simplest lazy kate consists of wooden bars with a metal rod running between them. Most hold three or four bobbins. The bobbin sits on the metal rod. Other lazy kates are built with devices that create an adjustable amount of tension, so that if the yarn is jerked, a whole bunch of yarn is not wound off, then wound up again in the opposite direction. Some spinning wheels come with a built-in lazy kate.

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Wikipedia