Discrimination method of abrasive cloth

Sand cloth can be divided into two kinds of gauze, pure cotton gauze and polyester cotton gauze. If you buy it, how to distinguish it? It provides a way for you:

You can find a lighter and burn the abrasive cloth you bought with fire. After burning, you can twist the ash with your hands. If it is grey, it is pure cotton abrasive cloth; if there are small particles after burning, it proves that it is not pure cotton, it may be polyester cotton. This method is very simple. It only takes two minutes for a person to judge.