I don't remember if I read this on this thread, but you should not put insulbright into the microwave. It catches fire because there are small metal particles in it. The potholder "bowls" are meant to go into the microwave so that you have something to grab onto to take the hot bowl out. So be sure not to use insulbright for them.
My very favorite potholders that I use every day of my life are two layers of an old towel. Just surged around the outside. They've been burned, patched and mended. A friend threatened to give me some new potholders when she saw mine, but I said, Please don't. I won't use them. I have a few nice ones to get out for "company", but I will use my old ones.