Intarsia in the Round

A special concern for the Whistler sweater is the sections which require three colour stranding. If the colours were used evenly across the row, you would just have to carry all three with you across the whole round.

But Whistler has sections where the third colour is only used for small areas that line up vertically. So the question is, can you treat this like intarsia? Meaning you would not need to carry the colour all the way around, but could use it only where you needed it.

On the body of the sweater, I figured out one way to do it. It was a little awkward, a little slow (but any method would be), and a little fiddly. Just before starting the colourwork section of the sleeve I happened on a life-changing post on Ravelry which outlined another way. The final result is exactly equivalent to what I had been doing, but the method is more elegant, simpler, and easier to explain to boot!

Ready for some details? Here we go...

I'm knitting around with grey and white, and come to the section where I need to add some red:

I work with the three strands following the chart, working red, white, or gray stitches as indicated. When I get to the end of the red stitches, I simply drop the red and continue working in only grey and white again:
Now I continue the round until I get to the beginning of the section where I need red again:
Now I've got a problem. I need to knit with the red, but it is back on the other side of the section, where I left it.
What to do?

Well, when working the body of my sweater, I looped the red over to where I needed it and worked with the loop (not the end that goes to the ball).
This worked ok (especially if you worked continental with the red loop), but when I got to the end of the red stitches in that round, I would have to go back and adjust the tension of all the red stitches. (Unless I guessed the exact amount I needed and made the loop just the right length, but that never happened.)

As I said earlier, this method worked, but then I found out about method # 2 and found it far superior.

Instead of working with the red loop, you continue working the round without the red, but slipping every stitch that should be red:Continue working with the grey and white and slipping the stitches that should be red until you get to the red working yarn (or the last red stitch on that row--whatever's later).
Now you've "caught up" to the red yarn:
Now you flip your work over so you looking at the back (or purl) side:
You now have the red yarn where you can use it. And what you do is work back across the same section, slipping all the grey and white stitches you just knit...
and purling the previously slipped stitches with the red yarn:Do this until you reach the end of the slipped stitches:
Now flip the work around again so the right side is facing...
and then slip all the stitches from the left needle to right. (They've all been knit now for that row.)

When you get back to the grey and white working yarns, you are ready to continue that round:
Continue knitting with just the grey and white, and now when you come to the section with red stitches, the red yarn is waiting and ready for you:

So, every other round is done as normal three-colour stranding, and the alternate rounds are done with the slipped stitches/purled red stitches.

It really is ingenious. The post I read it in gave credit to a pattern in Interweave Knit's recent issue Knitting Traditions, but I really doubt they're the creators of the method. They "just" explained it and recorded it. People have probably been doing this for eons. (Can I say again how much I love the internet and Ravelry in particular? There's no one I know that could show me this method. Or no one who offered anyway!)

Learning something like this makes me realize that people are smart, and some of them are even damned clever.