Handknitters have enthusiastically adopted this system. So now, when discussing yarn weights with those who have learned the numbers and how they relate to yarn dimensions, they frequently say things like "is it a 3?". This is a little disconcerting to older knitters like myself who grew up referring to yarn weights with terms like "fingering", "sport weight", "DK", or "worsted weight".
From the chart on the CYC website, I have extracted the top two rows.
But machine knitting yarns are sold on cones, and they are often referred to by a different set of numbers. Numbers like 2/24 or 8/30. This is even more confusing to new machine knitters.
The best, simplest and most comprehensive reference I have found to explain these numbers is found on the website of a UK yarn company called Airedale Yarns. There is an older reference that was written in the 1920's, it is more comprehensive but also full of technical explanations, charts, tables and algebraic formulas, which makes for a heavy read.
The Airedale web page explains that wool and acrylic yarns are usually sold using the Worsted Count system. The Worsted Count system is based on the number of 560yd (yard) units in a lb (pound) of yarn. So, the number 2/24 means that there are two ends (plies) of yarn, each of which was spun to the thickness required to get 24 x 560-yard from a pound of yarn. Note: it's pretty thin. Like a 0 in the US system.
Cotton yarn is measured differently. The count is based on the number of 840yd (yard) units in a lb (pound) of yarn. The size is expressed differently, also. 20/3 cotton yarn means the yarn is spun to a thickness so that 20 units of 840 length from a pound. Then 3 ends, or plies, are spun together to make the 20/3 yarn.
Notice that the relative position of the thickness of the yarn and the number of ends are flipped between the Worsted Count system and the Cotton Count system.
This screenshot from the Hobbii website shows that they give buyers both the cotton count and the Traditional name. The Craft Yarn Council would call an 8/4 cotton yarn a "1" size yarn.
The Airedale web site also gives as an example the New Metric count system. It is similar to the Worsted system, but instead of number of yards in a pound, it is measured based on meters in a kilogram. I have some cones of yarn in my stash that use this system. These cones are labeled with NM after the numbers.
Just to make it even more confusing, many hand and machine knitting yarns that are sold in the UK are described as 3-ply, 4-ply, and so on. So if the pattern was published in the UK, it may call for 3-ply yarn. This does not necessarily mean 3 ends or strands of yarn are plied together, but instead is based on yarn weight that was traditionally spun in Scotland to a certain thickness. The Airedale Yarns site explains:
"On Scottish Islands throughout the 17th and 18th centuries whole familes would knit sweaters, socks, accessories and stockings both to sell and use. It is believed that the first yarns to have a consistency of thickness that was measured and noted was from these islands. It was a yarn with 4 fine ends of wool twisted together and was the standard weight for knitting much of their knitwear. This thickness created a lightweight, flexible fabric that wasn't too heavy and was perfect for socks and executing complex designs such as Fairisle. This thickness is what is now known as 4ply, even though the knitters in Scotland probably wouldn't have called it that.
When two ends of this "4ply" yarn were twisted together they would have been used for thicker, warmer garments. Again the knitters might not have referred to this yarn as Double Knitting, but it is what we now call it. So 4ply was essentially the benchmark for knitting yarn thicknesses in the UK, double it up to create DK, double it up again to create Chunky, double it up again to create Super Chunky, and of course if you halve it you create 2ply. The very thinnest and very thickest of these terms are open to interpretation as not all 2plys and super chunky are quite the same as each other, but it's a guide."
In the back of every issue of the magazine Machine Knitting Monthly, which is published in the UK, is a table under the heading "Industrial Counts" that converts the Worsted Count yarns into the ply system.
Using this table as a reference, I have created my own table.
For an example, I have several cones of Forsell Naturell. It is a blend of wool and alpaca. Boldly on the label it proclaims "Knit as 3 ply", although the yarn appears to me to be a lace weight.
So, what yarn weights can be used on knitting machines? The Airedale yarns web site also includes a section to discuss this, along with weaving setts and WPI.
5.6 Gauge - Standard Gauge (4.5mm)
Beginning with 1ply and a maximum of 4ply. You can use really fine yarns like 2/30’s for lace shawls and the like and for draping fabrics.
2.8 Gauge - Chunky (9mm)
This gauge of machine can take Double Knitting and upwards. Aran or Chunky weight would be the maximum if you are knitting every needle, slightly thicker if you use every other needle. You can use really thick yarns to work knitweave as well which is where you knit with a thinner yarn and “weave” the thicker yarn through the knitted stitch.
My opinion is that the standard gauge machines are really pushing to use a DK weight yarn. You have to use the largest stitch sizes, like MT 9 or 10. You may want to do this to take advantage of having 200 needles on the bed, but you are giving up the ability to set the tension three or four tensions higher for binding off or other hand manipulations like crossing cables. The mid-gauge machines, like the LK-150 or the Brother KX-350, are better suited for handling DK and sport-weight yarns.
