Originally Posted by
ghostrider
It will be generations from now, however, before there is actual proof, one way or the other, whether poly sewing thread cuts through cotton fabric threads. It simply hasn't been in use long enough at this time, making all opinions merely speculation at this point.
I have two quilts my mom made when I was a kid. One is so soft with cotton fabrics, the other is rough with polyester blends. She used polyester thread in her piecing and quilting, unfortunately the cotton fabric quilt is falling apart along the seam lines and quilting lines. This is a well loved quilt that I have now washed a final time and put it up so it doesn't get more wear and tear.
The polyester quilt we couldn't kill if we tried, still has the fudgesicle stain from 2002, some random smear I can't identify.
My quilt instructor (she used to be a textiles teacher back in England about 40 years ago) explained once that polyester thread will cut the natural fabrics over time. I believe it as I have the quilt to prove it.