If a pattern features rib at a cuff or a welt, chances are it's to give elasticity and snugness. It would be a pity to take away some of that stretchiness when you cast off, so a very common instruction is to "cast off in pattern".
We get asked a lot at the counter what that phrase means, so here's the details. It follows on very nicely from our last technique post on working stitches as they appear
, too, because it really just combines that trick with a straightforward cast off.
Just as with a standard cast off, you start by working two stitches. The first two stitches in our row are bumps, so they get purled.
Again just as with a standard cast off, you cast off the first stitch by leapfrogging it over the second one, and the picture shows that happening.
At this point, you've purled your stitches and then cast them off. Looking at the next stitch, it needs to be knitted in order to keep the rib pattern:
So the next step is to move the yarn to the back of the work between the needles (because you're going from purl to knit) and knit the next stitch:
Then pass the previous stitch over the one you've just knitted:
And that's it! If a stitch needs to be knitted to keep the rib sequence, then knit it, and if it needs to be purled, purl it, and leapfrog the older stitch over the newer in the usual way as you cast off.
And finally, a couple of pictures to show the effect. The righthand portion of the stitches in our sample was cast off in pattern, and the lefthand section was cast off by knitting only without purling. It's very easy to see where the change was made - the knitted edge has nothing to do with the rib below it and splays out, but the cast-off-in-pattern section ripples pleasingly with the rib.
It's when the cast off is stretched (as it will be when you wear the garment) that the difference is really noticeable. The cast-off-in-pattern section stretches as much as the ribbing below it, avoiding that uncomfortable overtight edge.
So the welt of your topdown cardigan can be as supple as the work above it. It'll wear better too, because the edge isn't strained. No more top-down hats with forehead-hurting edges, either!