This post interests me greatly especially since today I ran into a lady that sews and owns her own shop. She doesn't really quilt anymore too much and doesn't like machine quilting (which is fine no qualms there). She did however make sure that I knew that she definitely would only use polyester thread with polyester fabric and cotton thread with cotton fabric. She wanted to know where I was getting my info that it was alright to use polyester thread on cotton fabric. I said that I had a lot of sources online. She said, "oh so you believe everything you see online?" Well no not everything..I am not naive,but there is some validity to what I find in my research!! There I stated my piece. Had to get it off my chest to someone and this seems like a good place!