I do not have time to read this at the moment, but plan on it. One time when I was in a fabric store I asked the lady if a particular piece was cotton, she was not sure. I said I would try a burn test on it when I was home. It was reasonable, the ashes I had left were soft what there was of them, so I figured cotton. When I have burnt polyester it the ash is hard and it gave off black smoke. Not sure if I was right, but thought I was. Thanks for sharing.