I have used sweatshirts and t-shirts along with one layer of insulbrite. That combo seems perfect to me. However, I am going to change and use one layer of batting and one layer of t-shirting. I am having second thoughts about insulbrite. It has little threads of metal in it, so if someone were to put a pot holder with that stuff in it, into a microwave,wouldn't it cause arcing? Definitely not good for the microwave. It would be rare, but it could happen.