my quilting teacher said she always uses cotton thread for piecing and then polyester for the actual quilting. Is there a reason for this? I used cotton (the same thread I pieced with) for my quilting and had no problems with the thread at all. On my 2nd quilt I free motioned I used poly and it kept breaking or the tension was off on the bottom and made it look like a binding stitch. Anyone know if it's ok to quilt with cotton? It worked better for me.