We make the soup bowl microwave potholders. We use 100% cotton for the fabric, batting and thread. BUT, we have a note on them to use for maximum 3 minutes. This is plenty of time to heat items. Microwaves work on moisture and the potholders have no moisture (this is also the reason that folks have problems with making popcorn in some microwaves). Most baked potatoes take much longer than 3 minutes to cook, that could be the problem.