Great Wall Pullover: Colorwork Tricks
When you're working tapestry colorwork, you may come across a place where you'll need to work backwards to get the effect you're looking for. Just such a case occurs in the Great Wall Pullover, by Moon Eldridge, in the Fall 2013 issue of Interweave Crochet. Working backwards helps equalize the natural slope of the stitches, so your graphic pattern will not lean and distort the image.
There are several ways of working single crochet in reverse. One way is learning to crochet with your non-dominant hand, but that can be a bit tricky and take some practice. Another way is by using the "purl single crochet", as Moon refers to in her pattern.
To work this stitch, you will hold your working yarn in front of your fabric and, working from left to right (or right to left, if you are left handed) insert your hook from the back of the fabric to the front through the next stitch. Yarn over and pull up a loop, yarn over and draw through both loops on your hook. It is very similar to working a reverse single crochet, only you will insert your hook from the back instead of the front, to avoid twisting the stitch.
To work this stitch in tapestry colorwork, you will work over your carried yarn just as you would normally, thought it will be held more to the front of your work on the wrong side rows (which are still worked with the RS facing). Changing colors works the same as for standard tapestry, where you will pull up a loop of the new color on the last yarn over before the change. Be sure to switch your yarns in such a way as to continue working over the carried color.
See the photos below for a step-by-step view of working tapestry single crochet in reverse.