As a new knitter, there is a period of time in which you go through the motions without fully understanding the effect of those motions. Once you understand the both the motions and their results, you really take control of your knitting and graduate to a new level. This week I want to focus on single decreases: first, their effect and use, and second, some motions to achieve them.
The effect: Decreases are used to remove stitches from your work. When they're used alone, they shape a garment, making it smaller. When they're used in conjunction with increases, they cancel out and serve to create a textured or lace design.
The motion: There are multiple ways of decreasing one stitch. One of the most basic is k2tog [knit two together]. It is an easy, beginner-friendly decrease as it utilizes the exact same motion as the familiar knit stitch, only it is worked into two stitches at once.
The next most widely used single decrease is ssk [slip, slip, knit]. It is worked by slipping two stitches knitwise [that is, in a front-to-back or away-from-you motion] to the right hand needle, then placing your left hand needle through the front of both stitches and knitting them together from this twisted stitch position.
As you become familiar with ssk, you may think to yourself, 'why don't I just insert my right needle into the back of these two stitches on the left hand needle without slipping them? It seems like the same motion and stitch set up'. Well, you can do that, but the stitch you're working is now k2togtbl [knit two together through the back loop]. The resulting stitches are very similar, but by slipping the stitch before working it in ssk, you eliminate a twist in the final stitch. It is a small detail, but one worth mentioning.
One last single decrease I'll mention is skp [slip, knit, pass]. This stitch is worked by slipping one stitch to the right hand needle knitwise, knitting the next stitch as usual, then using the left hand needle to pass the slipped stitch over the knit stitch and off of the needle.
Note: They are all interchangeable, but when making a substitution consider the aesthetic of each stitch and be consistent throughout your work. K2tog will yield a stitch that leans to the right, while ssk, k2togtbl, and skp yield stitches that lean to the left. It is also worth noting that skp is most closely resembles a mirrored k2tog, if you're a stickler for symmetry.