About double knitting

(ETA: Looking for information about how to rib in double knitting? Check out this entry instead. Or, if you're looking for information about double knitting in the round, check out this entry. Or, if you're looking for how to cast on for double knitting, check out this entry.)

Still no knitting progress photos to show today, so I continue with my ploy of distraction. :)

Since I wrote about one of my double knitting patterns last time, I thought it might be helpful if I followed it up with a bit of an explanation of how double knitting works.

Double knitting is a way of working two layers of knitting simultaneously. You can work it so that these two layers are attached to each other (thus creating a fabric which is twice as thick as regular knitting); or you can work it so that these two layers are unattached and you're really knitting two separate items at the same time - for instance, socks.

So...how does it work?

Well, have you ever done ribbing? (Probably you have.) You know how in ribbing, the purled stitches recede, making the knitted stitches kind of leap forward? This phenomenon is especially pronounced when you do 1x1 ribbing (i.e. K1, P1). With 1x1 ribbing, the purled stitches recede so severely that the knitted stitches kind of "sluck" together completely, hiding the purled stitches altogether, and making it look like stocking stitch from the front. (Except that it's stocking stitch half as wide as the number of stitches you've been working with, since all the purled stitches are "invisible".)

Well, if you turn a piece of 1x1 ribbing around (so that the purls become knits and the knits become purls), you will find that the same thing has happened on the other side, just in reverse. The knit stitches (which of course look like purl stitches from the other side) are receding, making the purl stitches (which look like knit stitches from the other side) "sluck" together, so that even on the reverse side, it looks like stocking stitch.

Well, that's the principle behind double knitting.

To turn 1x1 rib into double knitting, you use two strands of knitting: one strand for the knits, one strand for the purls, bringing both strands back and forth, back and forth, front and back of the work as you're switching between knit and purl stitches.

So...what's happening when you do it that way? With the first strand, you're knitting half the stitches on the RS and purling them on the WS, so you end up making stocking stitch with your first strand. And with the second strand, you're purling the other half of the stitches on the RS and knitting them on the WS, so you end up making reverse stocking stitch with your second strand (and, of course, reverse stocking stitch is easily turned into stocking stitch just by flipping it over). But since the two strands never connect to each other while the stitches are being made, the two layers of fabric they create never connect to each other, either. You're working two pieces of fabric at the same time.

But wait, there's more...

If you want, it is possible to make these two pieces of fabric attach to each other as you're knitting them. This will create something which is twice as thick, and which looks like stocking stitch on both sides. How do you do it?

By switching things up.

Let's say you're doing double knitting (in the round, just to make this explanation easier), and your two strands are different colours: one black, one white. You've been going happily along, knitting all the white stitches and purling all the black stitches. You have a sea of white stocking stitch facing you, and on the inside of your work is a sea of black stocking stitch.

But then, what would happen if, for one of these K1, P1 pairs, you instead knitted with the black yarn and purled with the white yarn?

Two things would happen:

1. On the outside of your work, you'd end up with a single black stitch in your sea of white stocking stitch, and on the inside, you'd end up with a single white stitch in your sea of black stocking stitch.
   
   
2. At the point where you switched what the strands are doing, the black and white strands cross, hooking around each other, thereby attaching the two layers together.

Can you see the potential here? This technique means that you can do colourwork without floats. Reversible colourwork without floats!

All you have to do whenever you need to make a stitch appear in the opposite colour is to reverse which colour does the knitting and which colour does the purling.

Neat, huh?

(The only thing to keep in mind is that you want to do this colour reversal in more than just one spot, otherwise your work will be held together by just one measley stitch, and everywhere else the layers will flop apart...which will look pretty silly. But as long as you have some consistent colour reversals throughout your work, that won't be an issue.)

Double knitting can get more complicated than that. For instance, it's possible to work with more than two colours; also, there are ways to finagle it so that you have two completely different patterns on each side rather than the sides being the reverse of each other. I may write about that another time, but at least now you know the basic principle of double knitting (assuming that my explanation was at all understandable).

And I think it's cool as hell.

So there you have it - if you can do 1x1 rib, you can do double knitting. :) Go forth and knit!