After “uninventing” this technique of double knitting the button band for my Circumnavigated Cardi I had a few requests for a tutorial. I do like to spread the double knitting love, so here we go.
First, let us have a little crash course in double knitting. There are several different methods and variations on those methods for achieving this type of effect. From knitting a tube on two needles with a single strand of yarn, to knitting two layers with two strands, knitting a circle within a circle to two layer colorwork to… phew, well you get the idea. Each of these methods also has its various strengths.
For this application, we will be knitting two layers simultaneously with two strands of yarn; for when working such long rows this is the swiftest variation. If you have ever done stranded colorwork before this method will be familiar. You can hold each strand however you like, both in the left, both in the right or one in each (my preferred method). I also dislike purling continentally so I switch the yarns each row so I’m always working the knit side with my left had. Unlike stranded work where this is verboten due to color dominance, it isn’t an issue here. Do whatever works for you!
So how do you get two layers of knitting on the needles at same time? Simple, you intersperse the stitches of one side, every other one with the stitches of the other side like this.

This setup is the constant in all forms of double knitting. I like to think of the stitches on the needle as pairs, one for the front and one corresponding loop for the back. These merry little pairs like to always travel between needles together, kind of like kindergarten street crossing buddies.
Why double knit a button band? Lots of reasons! It gives the more tailored look of a folded hem with Stockinette stitch on both sides yet without having to sew down a folded edge. Working both layers at the same time allows the button hole to be worked through both sides and joined producing a sturdy piece. You can pick up, knit, bind off and be done just like a traditional Garter stitch band.
Double knitting is one of those things where if you’ve never done it before, just trust the directions and it will work- rather like turning a sock heel the first time. Still with me? Great, onto the instructions for making this work as a button-band.

To start, pick up sts along the edge as you normally would for any type of button band. This is usually 3 sts for every 4 rows, shown here in a contrasting color for visual simplicity.

Purl one row. This is the set up row and from this we will double the number of sts to create the two sides of fabric. You will also notice the pick up row gets “tucked in” naturally so that unstretched, you won’t really see it. This helps to disguise the increase row even further.

Now we will work our increase on every stitch across the row. It is pictured here after working halfway across the row, again for clarity. The best method for increasing like this is the Purl into stitch below increase.
To do this- with the yarn in front, insert the tip of your needle purlwise into the top of the stitch below the current one on the left needle. You can lift this stitch onto the left needle to purl it, or purl from where it is.

After you have purled into that stitch, move the yarn to the back and slip the next stitch purlwise (the one that was above the stitch you just worked into). You now have a happy little pair, one stitch for the front and one for the back.

Work each stitch across the row this way until all stitches are doubled.

Turn your work and switch to a needle one or two sizes smaller and you are ready to start double knitting. *Note: In double knitting you will almost always need to go down a needle size or two because the stitches from the second layer squish in-between the other stitches and spread them out creating a looser gauge than a single knit fabric.

With a second ball of yarn (Yarn A) and *with both strands in front, purl 1 in Yarn A, with both strands in back, knit 1 with Yarn B, repeat from * across row. Your first row of double knit is complete. Turn your work and be sure to twist the two strands at the beginning of reach row to close the sides (the top and bottom of the button band). Repeat between * * until you have worked the desired number of plain rows before the buttonhole row.

Buttonhole row: Continuing in double knit, work the desired number of sts until you reach the placement of your first buttonhole. Bring both yarns to front of work, slip 2 sts (1 pair of front and back layer) then move both yarns to back and drop them there.

Slip 2 sts (1 pair) from the left to right needle then pass the first slipped pair of sts over these. Repeat two more times for a total of 6 sts (3 pairs) bound off or for however many you need for your size buttonhole. Then slip the last pair of sts on the right needle back to the left needle and turn work.

Pick up both strands and holding them together cast on 4 sts (or however many pairs you bound off + 1) using Cable Cast-on or Knitting-on Cast-on. The Cable Cast-on produces a neater edge I think, but I found the Knitted-on Cast-on a little easier to work (and is what is pictured here). Instructions for either of these cast-ons can be found here. Remember to work cast-on with both yarns held together (double-stranded). Turn your work and if the WS of the piece is facing you (such as in this example) move the both strands to the front and if the RS is facing you move to back.

Slip 2 sts (1 pair) from the left needle to right needle and pass the last cast-on pair over. Continue in double knitting repeating buttonholes where needed to end of row. On the return row work each loop of the double stranded cast-on sts as one stitch, your little pairs are back. Continue working in double knit until ready to bind off. Note: Remember to twist the yarns at each end (unlike in this swatch *cough*). This will also help neaten up the edges.

To bind-off, a very simple bind-off you can use is similar to the three needle bind-off. Using your original larger needle, simply k2tog (each pair), *k2tog, pass first stitch on right needle over the 2nd and continue from * until all sts are bound off. That’s it!
Another alternative for a seamless edge is to graft both layers together. You can even do this with all the sts still on the same needle (this is how I bound off the ends of my cuffs on the Circumnav Cardi) or separate the two layers onto two needles to work traditionally.

The “guts view” to prove it really is two separate layers in there. You can see that both layers will be joined at the buttonhole making them extra sturdy, huzzah!