Socks are chiral

Left glove, right glove.
Left shoe, right shoe.
Left sock, right sock?

Socks generally don’t care which foot they’re on. That is, even though our left and right feet are shaped differently, socks adapt. They go both ways. So it isn’t often that you have to think of the “handedness” of a sock.

Times have changed!

I recently started knitting another sock. I got through two inches of ribbing and then shifted into regular “stockinette” stitch for the leg of the sock. But instead of knitting around and around and around, I found I had to purl around and around and around. This seemed odd. I was pretty sure that I was knitting the last time I made a sock… but now I had to purl? (Not only that, but purling is (or feels) slower than knitting, for me. Vexing.)

Then it hit me. A sock is knit as one long spiral, around and around. So if you start going clockwise around the outside of the sock, you’re going to be knitting. But if somehow you start by going counter-clockwise, as I apparently did, you’re going to be purling. That is, socks are chiral! They either twist to the left (clockwise) or twist to the right (counter-clockwise). The yarn, I mean. Once the knitting/purling is done, you can’t (or at least, I can’t) tell the difference, and yes, the sock will still fit either foot. But the chirality is still there, buried deep in the sock fabric.

I’ve now made it down to the heel flap, which involves alternate rows of knit and purl. Aha! I think this means that I can correct my error, if I end on a knit row instead of a purl one, enabling me to knit the rest of the way down the sock. We’ll see!

Update (10/12/07): Yes! It worked! I turned the heel and now I’m back in the regular, clockwise (left-handed) mode. Whee!

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I knew this already. I learned something new!