As you get further into the craft of knitting, you begin to get into the mechanics of it, how a stitch is made and what makes a stitch look the way it does. From there it’s a short jump from why a k2tog (knit two together) looks different from a ssk (slip, slip, knit). Which brings you to the idea of “leaning” — left leaning decreases and increases and right leaning increases and decreases. and that brings you to the idea of symmetry.
To use this shawl as an example, the right border (that’s the direction you’re knitting from) is (ssk, yo) x 3. The left border, however is (yo, k2tog) x3. In the first place, you want the border lace on one side of the shawl to be the mirror image of the border lace on the other side, so you have to reverse the stitch order on the left border in order for that to happen. But there’s something else going on here: stitch orientation. Even though they’re both -1 decreases, an ssk is different from a k2tog because of the orientation of the stitches. In the ssk,, the two stitches are slipped knitwise before they’re worked, which turns them around to the right, so instead of being oriented parallel to the needle like a knit stitch, the worked ssk stitch “faces” 45 degrees to the right. This affects how the stitch looks and how it hangs. On the other hand, a k2tog “faces” 45 degrees toward the left. So, when you are working with left/right symmetry, you need to know your left/right pairs of increases and decreases.
One of the first things you learn in knitting is front/back symmetry. You learn that the opposite of a knit stitch is a purl stitch when you learn to work stockinette stitch. The lace panel at the center of this shawl is a case in point. The right side is worked: k1, (k2, yo, k2tog, k1) x 3. It would seem logical that the wrong side would be: p1, (p2, yo, p2tog, p1) x 3. Nope. Turns out that p2tog is not the exact opposite of a k2tog. Turns out that the exact opposite of a k2tog is a ssp tbl — slip two stitches knitwise and purl them through the back loop. That’s the only way you can get the stitch before the “crisscross” to lie flat. If you p2tog, it’s twisted and doesn’t look right.
I’m contemplating ripping out and reworking a whole half of another shawl I’m working on because of the way the p2tog doesn’t look right on the wrong side. I’m trying to decide how bad that bugs me.
In other knitting news, all that’s left to make this a FO is to weave in one last end. The pattern is here if you’re interested.