30 and 31 of 51 Yarns: S to Z and Back

This post is part of a spin-along through 51 Yarns by Jacey Boggs Faulkner, in the Wool n’ Spinning community. For other posts in this series, check here.

I spun these yarns way back at the beginning of April, but it took the rest of the month for me to get around to swatching them! Mostly because I’ve been completely distracted by spinning other things, so I’m not complaining.

This month, we had an interesting assignment: spin a yarn the “normal” way, with singles spun Z and plied S, and then spin another yarn the opposite way.

I don’t want to get very detailed about it, but the idea of S and Z twist comes from looking at the middle bar of those two letters, and likening that to the twist of a yarn. If you look at the two yarns above, you’ll see that the yarn on the left has the two strands wrapping around each other leaning to the right, like the middle bar of a Z, and the other has the strands leaning left, like the middle bar of an S. Now, we could just say “left” and “right,” but this is confusing for those who have spinning wheels with different drive wheel configurations, and maybe drop spindlers too.

Now apparently, most knitting yarns (commercial or handspun) are made with the singles spun Z and then plied S, like the yarn on the right above. This is because many knitters add a little bit of S twist while they knit, and if the yarn’s last plying step is in the Z direction, then they would untwist their yarns as they knit. Better to add a wee bit of twist than take it away, apparently. Other yarns, like crochet cotton for example, might be conventionally spun in the opposite direction, for similar reasons.

I do usually spin my yarns in this manner – Z spun singles, Z twist ply, but I couldn’t tell you why I do that. I just picked a direction and stuck to it, to be consistent, and by chance was following a convention.

Now, I have never noticed myself adding or removing twist in my knitting, because I am a flicker. That means I hold the yarn in my right hand, holding it up with my index finger, flicking it around the needle rather than wrapping it with the whole hand. In ancient times, I did a video about it here. Rachel had attributed her twisting of the yarn to her continental style of knitting, holding the yarn in the left hand. So I wondered if I do this at all?

My first step was to create two identical yarns: one “normal” – Z spun, S plied; and one opposite – S spun, Z plied. I used up a bit of merino/silk that was kicking around in my stash without a purpose, and successfully created two yarns identical in everything but direction. Same WPI, TPI, and AOT, and grist within the margin of error. Making them was unremarkable; it was a little weird remembering to get the drive wheel going the opposite way to what I was used to, but not difficult. I plied from center-pull balls in both cases, and made my usual slightly-overtwisted yarn.

Conventional yarn: Z spun, S twist. 3 degrees of bias.

The next step was to wash and swatch. My yarn had come out at 11 WPI, so I knit it up on US 5 needles. I washed the swatches, but didn’t stretch or pin them to dry, because the real test is: do they bias?

Opposite yarn: S spun, Z plied. 0 degrees bias.

To the unassisted eye, both swatches look pretty similar. A bit of geekery: In every stitch of stockinette, which is V-shaped, one leg of the V is more tightly twisted than the other. This is because the loops at the top and bottom of each stitch are leaning back to the bottom of the fabric, which rolls the yarn outward, like a shawl collar, to wrap around the bottom of the stitch above. This adds a tiny bit of S twist to the left leg, and a tiny bit of Z twist to the right leg. so in the S-plied yarn, the left leg of each V is more tightly twisted, and in the Z-plied yarn, the right leg is more tightly twisted. I find this more noticeable the higher the twist angle of the yarn. Man, I’m just all about the letter shapes today.

OK that was a serious digression. So the main test of these yarns is, do the swatches bias? I expected the answer to be “no,” or for them to bias the same amount in either direction. Surprisingly, this is not what happened. The conventional S-plied yarn had about 3 degrees of bias from center, and the Z-plied yarn had 0 degrees. (Why yes, I keep a protractor in my notions bag. Don’t you?)

Conventional S-plied yarn on top, Z-plied on bottom. You can’t tell because the swatch is a little tilted, but the top one is slightly biased, and the bottom one is dead straight.

So, I do slightly change the twist when I knit. I add a teensy bit of S twist, making the S-plied yarn more overtwisted, and making the slightly-overtwisted Z-plied yarn perfectly balanced. What that does to my fabric depends on how tightly twisted my yarn is, but it is good to know. I’ll definitely keep plying S for yarns I want to be sturdy, as the extra twist will only help. But for more gently-used items? Maybe next time I’ll give Z-plying a try.

2 thoughts on “30 and 31 of 51 Yarns: S to Z and Back

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