I've been given a new yarn to sample, and it's a singles yarn. I know that as the operator of Canadian Guild of Knitters, I should love all yarns, but the truth is, I have a bias against singles yarns, and it's because I'm a handspinner. Sure, they have their place, and you get great colour definition with a singles yarn, but quite often, a singles yarn will knit up in a way that it slants off in one direction (as in the photo above), or the stitches will spiral around the leg in the case of knitted socks.
What causes this? The short answer is a lack of balance.
Remember spinning around on the swing when you were a kid? The physics of that action is this: when you turn around, you're putting energy into the chains or ropes on the swing. When you let go, that energy has to go somewhere. It's the same for yarn.
When fibres are brushed out and spun together, energy is put into the strand of yarn. Plying it allows some of that energy to disburse, and, ideally, create a balanced yarn. If there is too much twist in the single plies, or too much twist is put into the yarn when the strands are plied, the yarn will be out of balance. (I have had plied yarns skew on me, too -- read on!)
The problem is that a singles yarn doesn't go through the plying process. Sometimes, that means that the finished yarn is "high energy." Some singles yarns are blocked (wetted and weighted) before they are sold to "set the twist" to minimize skewing. But it can still show in the knitting!
So what's a knitter to do?
You can check for balance, simply by taking a couple of arm-lengths of yarn, holding the ends together, and letting go of the middle. If the yarn is unbalanced, you will see some twirling, just like on that swing!
You can knit a swatch. If your stitches look more like the ones in the orange sample in the photo, you might have an unbalanced yarn, but as long as the swatch knits up square, you're in good shape. If it skews, you may need to re-think your project.
For some reason, if you have a yarn that is skewing, you can try another swatch in garter stitch, ribbing, seed, or double seed stitch. Back in 2008, I reviewed Cascade 220 for Knit Together, and got a swatch that slanted to the left. At that time, a wise spinning friend of mine said "try ribbing or seed stitch or any other pattern where there are an equal number of knits and purls." Well, would you look at that: it worked!
I find it interesting that the yarn at the top of the blog, a singles yarn, skewed to the right, and the plied yarn I worked with in 2008 skewed to the left. The answer could lie in the fact that most of our knitting yarns are spun Z and plied S, so the singles yarn went in one direction and the plied yarn in the opposite direction.
If you find yourself with a yarn that skews when you knit it, try one of my solutions and see if your yarn will redeem itself!