It's very common to decrease by using a knit two together (K2Tog), but there is another decrease stitch you should know: knit two together through the back loop (K2Tog TBL). This stitch is essentially the same decrease, but it adds a little twist to the pattern and it can also be used to correct stitches after a mistake.
Most patterns use the abbreviation TBL, for "through the back loop," in either lower or upper case. You also might see it written as "in the back of the stitch" or with a "-b" added to the stitch, such as K2Tog-b or K1-b.
How to Work K2Tog TBL
To perform this decrease, you work the same as if you were knitting through the back loop of just one stitch, but instead, you go through two.
- Your right-hand needle goes through the back loop of the first stitch, then the second.
- Make a knit stitch as normal, pulling both loops off the left-hand needle.
- One stitch will remain on the right-hand needle.
A purl two together through the back loop (P2Tog TBL) stitch is exactly the opposite. It is most often used to decrease and twist on purl rows.
What Does a K2Tog TBL Do?
The most common reason to use a K2Tog TBL is to twist the knit stitch while decreasing. It serves the same purpose as a single knit stitch through the back loop and creates a nice texture in the finished fabric.
You might use the K2Tog TBL if you want to decrease and shape a pattern worked in something like the twisted stockinette stitch.
Use the Back Loop to Untwist Dropped Stitches
Just like other back loop stitches, you also can use the K2Tog TBL while correcting a mistake. Let's pretend—though it often happens in reality—that you had to frog your knitting past a row with a K2Tog stitch.
While you're putting the stitches back on the needle, they get twisted. Rather than fumble and attempt to straighten them out, you can K2Tog TBL through a decrease and it will automatically untwist the stitch.
More Common Decrease Stitches
It's very true that you will use the K2Tog TBL in very rare instances. Most knitting patterns will use one of these decrease stitches instead, so you will find them to be more valuable in your projects.
- SSK (Slip, Slip, Knit): The opposite of a K2Tog, this stitch slants to the left rather than the right. In very rare occasions, you may be asked to knit it through the back loops as well (SSK TBL).
- P2Tog (Purl Two Together): Often worked on the purl row of a pattern, this is a very common decrease and it's easy to do.
What Decreases Are Used For
In knitting and crocheting, when you want to change the shape of a project to either create a pattern as in cable stitch or for fit as in shaping the arms and shoulder areas for a sweater, decreases are made to narrow the finished piece. Essentially, all you are doing is narrowing your knitting by decreasing the number of stitches on your knitting needle.