It is not often that the American language surpasses the Queen’s English in breadth and subtlety. However, when it comes to describing the stuff one knits with, the Yanks have the edge. “Wool” is really an anachronism as, these days; it is very seldom that one knits with wool, or even a wool blend. Acryllic thread is by far the most common medium, although it is possible to knit with raffia, nylon, cotton, silk, and exotics like alpaca, mohair and angora. The generic American term – yarn – describes any string-like substance that can be used in the knitting process, and is an easy way to talk about knitting.
All that said, wool is still more closely associated with knitting than any other yarn. And sheep’s wool is what comes to mind first. More than 70% of the world’s wool comes from Australia, China, the United States and New Zealand. (It is well-known that in New Zealand sheep outnumber people by about 10-1.) Sheep are shorn once a year, by highly skilled shearers who can remove the wool from a sheep in as little a minute.
Next, the wool is scoured, or cleaned, to remove most of the greasy substance known as lanolin. The famous Aran sweaters of Ireland are made with wool which still has a high lanolin content, giving it a waterproof quality, as well as being wonderfully warm. However, some people find wool irritating or scratchy. In this case, it might be better to use a blend of wool and acrylic, or wool and silk, even wool and bamboo. Wool, being a great insulator, helps keep us warm in winter, and is also used by Tuaregs and Bedouins to keep themselves cool.
Then the wool is sorted and either sent to a commercial mill or processed on the spot by carding and spinning. Carding, done with a comb, separates the fibres and fluffs them up. Spinning is the process that converts the fibres into threads of various thicknesses. Very fine strands may be combined with others in a rope-like twist giving two-, three- or four-ply. Wool varies from very light, soft baby yarn to bulky, quick-knit yarns, each requiring different thickness needles. But it is not so simple, because some people knit more loosely than others. This is known as tension, and any knitting project must start with a swatch – a square worked in stocking stitch that is used to measure how many stitches per inch you knit. Every pattern states the gauge. If your gauge is looser, you need to use a smaller needle; if your gauge is tighter, you need to use a larger needle.
Wool is one of the easiest yarns to knit because it is elastic and forgiving. This means that it can stretch if necessary, but also that it will retain its shape, allowing for an even tension and appearance. On the other hand, wool felts easily if immersed in hot water and agitated, that is, put through the washer and dryer.
With many weights and qualities of pure wool, as well as blends, it is possible to find a perfect match between your project and your choice of material.