When I first started quilting, I was warned "Don't use polyester thread because it can tear the cotton fabric!" I've since found out that most cotton clothing is sewn with polyester thread. I can't think of anything that gets more use than a shoulder seam - and NO tearing! So... I now use polyester thread or whatever I have on hand. I do prefer to buy cotton for piecing because I don't like to deal with stretch. I haven't worked up the courage to try stretchy fabric as a backing. I'd love to try Minkee.