I remember making some cotton table napkins years ago, before I really got into quilting, and I tore the fabric to make the squares, thinking I would get a really even square since it would be totally on grain. Those napkins have been a pain ever since, in trying to iron them and fold them into quarters. They never seem to want to fold into a square properly. I guess that's what scared me off of tearing. But, maybe that fabric was just off grain - is that a possibility? I could never quite figure it out......