When I initially tried double knitting, one thing that turned me off was how messy the cast-on edge could look. Casting on by holding both yarns together never looked very tidy to me, I wanted an edge where color A stayed cleanly on its side and color B did the same for its respective side. While working up my last hat, I came up with a great solution to this problem by modifying a tubular cast-on slightly. I then promised in a blog post to share the method, so without further ado, here it is: a modified tubular cast-on for double knitting. You’ll need: knitting needles, a piece of scrap yarn to cast-on stitches with (~3x the width of your cast-on edge), and yarn for both the front (A) and back (B) sides of the work. Here we go!
If you are knitting in the round, the number of stitches you need for either the front or the back.
If you are knitting flat, the number of stitches needed for the front or back, plus one.
Remember that in double knitting you have twice as many stitches total as are visible on either the front or the back. For example, if you want a piece that is 10 stitches wide, you will eventually have 20 stitches on the needles (10 front, 10 back), but using this method you would only cast-on 10 (or 11) sts. Make sense? Next, you’ll want to work two rows of reverse stockinette in color A (here, light blue), the color you eventually want showing up on the front of the piece. If you are planning to work your piece in the round, stitches should be joined and worked in the round here also, and you should also work in revers stockinette (purl every row).
3. Now the fun begins. Purl the first stitch using color B. Then, pick up the color A stitch from the first row of the piece. This stitch is circled in red above and should be visible as a bump sandwiched in between scrap yarn.
4. Knit this stitch, using color A. A quick note here about double knitting: if you are knitting a stitch (working on the front), both yarns should be held behind your work. If you are purling (working a back stitch), both yarns should be held to the front. If you only hold the working yarn forwards or backwards, you’ll get unsightly floats of yarn on the visible part of your work. No good!
6. Repeat to the end of the row. If you are working flat, end with a purl stitch. If you are working in the round, you’ll need to pick up a knit stitch last–it can be a little tricky to get that last one, but persevere! It’s doable. Your knitting should look something like the photo above.
At this point, you may notice that your knitting is beginning with a purl stitch in color B. While there’s nothing inherently wrong with this setup, it will make following many double-knitting patterns a little tricky, as they usually start with the front (A, or knit) stitch. Fortunately, it’s an easy problem to fix. If you are working in the round, simply move the beginning of your round over so that the first purl stitch is now the last purl stitch. If you are working flat, slip both the first knit and purl stitches off the needle, then put them back on the other way around (knit stitch, purl stitch). Knit the first stitch in color A, then purl the two color B stitches together.
Once you have that sorted out, work a row/round or two. Then it’s onto: