All Cottons Are Not Equal
Do you love to knit with cotton? Or have you been disappointed in the resulting garment? Did it shrink or stretch out? Did it Fade or pil? When choosing a cotton yarn, it is extremely important to consider how the intended garment will be used. Will it be washed? A Lot? Does it need to be stain resistant? Soft? Durable? Or will it become the thing you use to wash dishes? Do you hope it softens with age or does it matter at all? Well there's hope because all cottons are Not equal.
Like most yarn, cotton yarn begins as a mass of fibers. Different types of cotton have different length fibers and that directly affects the strength and durability of the yarn. Pima cotton fibers, also known as ESL(extra Long Staple), are longer than regular cotton yarns. The length of the fibers must be at least 1 3/8" to qualify as an ELS cotton. Pima cotton traces back to Sea Island cottons that were grown in the South Eastern United States in the 1700's and were later crossed with Egyptian cottons. This yarn was renamed for the Pima Indian's in the South Western United States who were growing Pima cotton from the early 1900's for the USDA. Peru and Australia and Israel are also producers of Pima cotton. The advantage of Pima cotton is that the longer fibers result in a stronger, softer, smoother yarn with greatly improved durability.
What about Egyptian cottons? Egyptian cottons are those that are grown in Egypt and are not necessarily ESL cottons. Egypt consumes most of the ESL cottons it produces, therefore only a small quantity of high quality cottons are actually exported from Egypt. This amount to about 15% of the annual global cottons on the market. U.S. Pima cottons are the cotton of choice for producing high quality knitting yarns.
There are also manufacturing processes that alter the cotton fibers which can improve the qualities of the yarn. Such is the case with mercerized or pearle cotton. In 1851 John Mercer developed a procedure treating cotton with sulphuric acid, caustic soda, as well as other chemicals. These treatments caused the fibers to straighten and swell. This process wouldn't realize its full potential until 1890 when Horace Lowe applied the Mercerizing process to cotton yarn and fabrics under tension. The resulting yarn or fabric had a high sheen and the greater absorbency which resulted in better dying results and less fading of the final product. If you want a strong , beautiful, non piling, non fading, soft yarn then this is the cotton for you.
Other factors to consider in a yarn are the weight and the ply. The number of strands twisted to create the yarn is the ply. The tighter the twist and the greater the number of ply, the stronger the yarn will be. This is important not only for the strength but also for the shrinkage or the stretch. Higher thinner ply yarns hold their shape better than thinner low ply varieties and are less likely to pil.
Pima and mercerized cottons are among the highest quality yarns in the world. If you want your projects to also be high in quality they are a good place to start.