CROCHETED RAG RUG PATTERNS 
How they work…and why some don't 
by master rugmaker, Diana Blake Gray

In back-and-forth crochet patterns, the only trick is to size the hook to the weight of the strip, and not work really tight stitches. Heavy fabrics and wide cotton strips don't work well for these types of rugs, since a prominent ribbed effect is created. 

So two schools of thought developed-one which called for bias cut strips of cottons, and the other which used straight cut (or torn) strips. Of course in moving away from the traditional straight strips, the rugs were supposed to be easier to make, but unfortunately the resulting bias rugs continued to stretch, even after they were made, and didn't hold their shape well.