LynnS what a fantastic idea!
I too have made potholders before, more decorative than anything else and have also used several layers of thick flannel remnants. I didn't try them on the stove, but did use them for hot dishes to keep my table from getting marred.
A friend of mine gave me some thick batting with silver on one side and had no problem with those. I used regular cotton fabrics on each project but do not know the name of the batting, as it was already out of the package when I received it.