S and Z

I am intrigued by yarn structure.  Until I started spinning I never gave it a thought that yarn is made from many choices of fibers (animal, vegetable, and mineral) but only two choices of twist (S or Z).  The twists are so named because of their resemblance to the middle part of the two letters.  Most yarns are spun Z and plied S.  Twined knitting yarns, and a few others, are spun S and plied Z.  This difference in twined knitting yarns compensates for the constant twisting of the yarns in that technique.

S plied and Z plied yarns

What many knitters don’t know is that the act of knitting adds twist to the yarn: S twist for conventional Western knitting, Z twist for Eastern knitting, where the yarn is thrown under the needle rather than over it.  You can check this out for yourself by using a tape measure and holding it firmly (don’t let go), wrap it around a knitting needle several times as if you were knitting.  Now unwrap it and throw the “yarn” the other way.  You are looking for the angle of the twist that develops near your hand holding the “yarn”.

Well, it turns out that is not the end of the story.  I have seen my students struggle, as I do, trying to make the SSK (a left leaning decrease) as neat as the K2tog (a right leaning decrease).  And plenty of knitters in my Aran classes have mentioned how their traveling stitches that go to the right are neat and consistent while those that travel to the left look stair-steppy.  I also noticed that when I work a Herringbone Braid (AKA Latvian Braid), the part that leans to the left sits up more and looks fuller than the part that leans to the right.  It got me thinking that just maybe, the culprit is the twist of the yarn and not knitter error.  I meant to investigate!

I finally got started one day by visiting the Green Mountain Spinnery right here in Putney, Vermont!  (If you haven’t seen the Spinnery’s new book 99 Yarns and Counting, run right out and check it out!)  I was talking to one of the owners of the cooperative, about twist and she produced a hank and a cone of some yarns they had created as an experiment in overspun–or energized–yarns.  The hank was a typical 2-ply, Z spun and S plied.  The cone had the same type and size of wool, but it was a singles yarn, spun S.  I was elated!  I took them home and plied up the cone (Z-wise) so it would be the exact opposite of the S plied hank.  It felt good to be on my spinning wheel again.  It is usually very, very lonely these days.

Then I washed the yarns, spun them in my washing machine to get rid of most of the water, and put them onto my yarn blocker from my swift.  They dried in a day and I balled them up.

Rinsing my yarn
Drying on the yarn blocker
Yarn: Ready to go!

Now to check my thesis.  I knitted up swatches of SSK and K2tog in both S plied and Z plied yarns.  (The swatches are worked with the K2tog on the right side of the center stitch and SSK on the left side.)  This is what I found:

S-plied yarn used in top swatch, Z-plied yarn used in bottom swatch


The effect was much more pronounced before I blocked the swatches, so now I am kicking  myself for not having taken before and after shots!   Still, to my naked eye, there was some improvement with the Z-plied yarn in the SSK lying flat.

Next, I wanted to work with some traveling stitches to see if I could make the left leaning twists look better using a Z plied yarn.  Looking at the diamonds below, the left leaning twists are on the left in the bottom halves, while they are on the right in the top halves.  Note: To make a right-leaning traveling stitch, I knit in the second stitch on the left needle, then the first stitch.  To make a left-leaning traveling stitch, I reached to the wrong side of the work, knit into the back of the second stitch, then into the front of the first stitch.

Z-plied yarn on the left, S-plied yarn on the right

In my opinion, the Z-plied yarn DID make the left-leaning traveling stitches sit more neatly, though still not as perfectly as the right leaning stitches did.

So what do these results mean for knitting these techniques?  We can’t use S and Z plied yarns in the same piece just so our decreases or traveling stitches will look good.  Definitely not!   I think the point is to recognize that small irregularities in our knitting are not necessarily our doing.  Instead of feeling annoyed or embarrassed by such minute details, we can know that this is a function of the yarn we are using and thereby get ourselves off the hook!

Still, I wanted to try one more thing…  I did one last swatch in a traveling stitch diamond pattern using a technique to compensate for the uneven tension.  This idea is inspired by Cat Bordhi who showed how to slip a stitch in the previous row of a SSK to keep the tension of the resulting stitch under control.  Could a variation of that work for traveling twists?

Slipped stitches of the traveling stitch

In this swatch I used the S-plied yarn.  In the bottom half of the diamond, I slipped the first stitch of the eventual twist on the wrong side rows.  This resulted in half the number of rows and enlarged traveling stitches.  Yes, I think they have a continuous flow, a smoother line, but they look much different from the right-leaning twists on the right side.

I was really pleased with the top half of the swatch.  Here I slipped the second stitch of the eventual traveling twist on the wrong side rows.  The left-leaning line still sits up a bit more than the right-leaning line of twists, but it is smooth and consistent looking.  The reason slipping the stitch works to minimize the looseness is that the one stitch is much tighter, having not been worked, and so it keeps its shape  even when stretched into a traveling stitch.  But it must be the second stitch of the twist, the one that lies below in the twist, that has to be slipped to tighten up the stitches.

So take what you want from this, knowing that the tension discrepancy is inherent in the yarn twist.  You can fiddle with it by slipping stitches, and at the very least, block carefully and thoroughly, but some days I just don’t want to work that hard.

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