The crab stitch is basically a reverse single crochet. Method four is meant for edgings where you want to minimize stretch. It's called a "surface crab stitch" since it's created on the surface edge of another piece, though most of us just refer to it as the "crab stitch." I had a beautiful knit sweater, but the neck used to stretch out way too much. I added the crab stitch to the edge and voila, no more stretching.

Talk Doctor Online in Bissoy App