I was thinking about the next steps in writing about matching yarn to projects and TPI or twists per inch popped up in my head. Just when I think I’ve covered something, another thing occurs to me. TPI was a new-to-me concept when I started researching hand knitting yarn structure. I knew it existed, but hadn’t really thought it through.
Woolen Yarn vs. Worsted Yarn
I’ve heard these terms for years. Mostly I am familiar with them in terms of wool fabric. In fabric tight, smooth yarn makes up tight, smooth worsted fabric, and fluffier, loftier yarn makes up less dense, more textured woolen fabric. I have heard my yarn and spinning friends talk about woolen and worsted yarn, but I never really connected the concepts to my hand knitting yarn. Simple concept. The fibers must be combed and carded to make worsted yarn. For woolen yarn, only carding is done. But fibers combed and carded can be woolen spun, and carded-only fibers can be worsted spun. I believe it is all a matter of equipment (commercial) or operator (hand spun)
I think it is more likely that we think in terms of soft twist, medium twist, or hard twist, and then variations between those because we don’t actually know what process the fibers went through.
Twists per inch can be visually counted, but what you see is how many twists there are times the number of plies. The twists per inch tells how tightly a yarn is spun or plied. What does that matter? It will impact the durability, drape, and how the stitches perform in the fabric you are creating with your knitting. This is a little like counting stitches or rows except at a finer scale and it is easy to lose count. Use a pointer of some sort and magnify if needed!
Single-Ply Twists Per Inch
A single ply yarn is twisted but it is more difficult to see the twists per inch. Measure off 1” and put markers (I used small binder clips) to mark that inch. Note the orientation of the markers to each other. Then, untwist one marker until the fiber is flat. I found that as soon I went past the flat point the clip wanted to spin back to its original position. So keep an eye on the fiber and the marker and AT THE SAME TIME, count the number of full and partial twists. My sample is Poems from Universal Yarn. It has color variation which helped me see what was going on. I counted 2.5 twists per inch. I also measured it after untwisting and between my markers it was a little shy of 1.25”.
Two-Ply Twists Per Inch
There is a formula to use once we get into yarn with multiple plies. There is the total bumps divided by the plies to get twists per inch (TPI). The two-ply in my sample at the beginning is Ramboulliet from Mountain Meadow Wool, a worsted weight. I count 7 bumps which divided by 2 is 3.5 TPI. When I unwound the twist I had approximately 1.25” of each ply. I also looked at Breeze from Anzula, which is a silk/linen blend. It is obviously much finer yarn, and I count 11 bumps, so divided by 2 it is 5.5 TPI.
Three-Ply Twists Per Inch
The formula is the the same, with 3 as the divisor. My blue yarn is Civility Sport from Elemental Affects, a wool and silk blend. I count 9 bumps, so the TPI is 3. I was curious about Civility Worsted, so I counted those bumps and got 10, giving a TPI of 3.333. Really curious now, I counted bumps on Elemental Affects Cormo sport and got 15 or 5 TPI. I also looked at Cricket from Anzula (above on left) which has 12 bumps, so a TPI of 4.
Four-Ply Twists Per Inch
My final look will be at two 4-ply yarns that are made outside the US. The first I no longer have a label for it, but it is worsted and I think is super wash. I count 10 bumps for 2.5 TPI. I also have Deluxe Worsted from Universal Yarn (yellow) which has the same count.
I saw some Provence from Classic Elite on my desk and grabbed that to look at too. It is a 3-ply yarn and I count 6 bumps, for 2 TPI. But when I untwist the three plies, each ply has twisted bumps. The bumps on this level are difficult to count, in part because there are also plies in each of these three plies. This level is fairly loosely plied, with the next level of 2 plies more densely twisted. The 2-ply level has 19 or 20 bumps, so a TPI of 4.75 or 5. I couldn’t find any information about what this type of ply is.
I admit I am beginning to take this picture a little further in my head. Remember, I’m not a spinner, so I’m not ever going to know what the yarn says when it is being spun. There may be more to say on this!