2-ply, 4-ply, Why Ply?
Simply put, ply is a measurement we use for yarn, like inches, yards, and meters. Unlike these other units of measurement, however, ply has no standard size. All of the yarns pictured above are made of a single strand of fiber. As you can see, they are all very different. An inch is always an inch, but one ply? That's another story.
There are several factors that determine the character of a single ply of yarn: the fiber, the spinner, and the tension.
FIBERS
Lofty fibers like wool, cashmere, or alpaca contribute a more dense, fuzzy strand, whether they are spun loosely or tightly. A single strand of silk is composed of two microscopic protein filaments that give it a sticky, strong texture. Cotton and other plant fibers consist of layered cellulose that are dried and spun into a resilient, smooth strand. Combining these fibers produces different ply strength and texture.
SPINNING + TENSION
Single strands of yarn are twisted together to increase the strength and size of the yarn. Twisting, or spinning, can be performed by hand, using a spindle or spinning wheel, or on a machine. Handspun yarn is characterized by thick-and-thin strands that are the result of changing tension on the yarn. It can be subtle or pronounced, to the spinner's taste. Handspinning also offers the opportunity to combine unlikely fibers for surprising results; for example, Ozark Handspun yarns are utterly unique. Today industrial machines can imitate handspun texture as well as create perfectly balanced yarn.
Each of these 2-ply yarns is spun from different fibers and can be knit on a range of needles, from US size 2 - 5. Up until fifty or so years ago, if you wanted to knit 2-ply yarn, you would use size 2 needles. 4-ply yarn? Pull out your size 4 needles. That is because there was one primary fiber on the market (wool), and one set of plies. Since a single ply yarn was common, it was easy to step up needles as the number of plies increased. A really bulky 8-ply yarn called for size 8 needles. The simple life!
The basic principal of this system still exists today, although there are so many wonderful fibers on the market that there is no steadfast standard. The 6-ply strand above consists of three 2-ply twists. Here are four examples of two-ply strands twisting into thicker yarns, from two 6-ply yarns on the right, to a sea green 8-ply and a bulky 12-ply.
Much of our popular knitting vocabulary comes from England, Scotland, and Ireland. Knitting weight, such as the 2-ply yarns shown above, is also known as fingering weight; these yarns are commonly knit on US size 3 needles. Double Knitting, or DK weight, means 4-ply yarn best knit on US size 6 needles. Worsted weight yarn, knit on US size 8 needles, is also called Aran weight, named after the Aran Island knitters and their legendary weatherproof wool.
Other knitting terms that were once precise measurements. One skein of yarn today varies in length; it used to equal 120 yards or 109 meters. A hank of yarn was the equivalent of seven skeins.
Today, there are nearly as many combinations of plied fibers as there are knitters. Needles are sized from toothpick to rolling pin. This is a lucky time to be knitting!
November 27, 2006
Reader Comments (5)
For some strange reason, people have started using "ply" to refer to a size of yarn. That is impossible. An 8-ply yarn has 8 strands of yarn in it-- it can be very fine, or the size of a rope-- it is still 8 strands put together into one yarn.
There was a standard as to measurement of yarns. It was based on the number of skeins of yarn that can be spun from one pound of fibre. This is dependent on how fine the spinner can spin; a larger number means a finer yarn (of wool). This gets confusing. Wool had a different system than cotton which was different than linen, and acrylic wasn't even considered then.
Today there are several different methods of measurement: tex in Europe, 1-8 by the Yarn Council of America, ply system in Australia. The best seems to be wraps per inch -- how many threads laid side by side in one inch. Another standard is yards per pound (ypp), or metres per kilogram (mpk). Obviously, 1500 ypp would be finer yarn than 1200 ypp.
Cotton usually uses a numbering system: 2/8 means a yarn of 2 plys each being of size 8 (standard measurement in cotton). 2/16 would be a finer yarn, being 2 plys but of size 16. 4/8 is a thicker yarn: 4 plys of size 8. 8/2 is 8 plys of a size 2 yarn.
And then we get into compound and cabled yarns; these are all differences in construction-- nothing to do with size.
I suppose we just all need to use the same language so we can understand each other. If we just measured the width of yarn in microns, that may be the only useful number! But the number of plys in a yarn only tells about its construction, not anything about size.