The batting and fabrics were sold as microwave safe from Keepsake. The President of Keepsake Quilting said there were no other reported problems with their batting or fabric in the kit so it had to be something I did wrong. Top thread was 100% cotton so it must have been the bobbin.
Before ordering the kit, I asked about the batting at a LQS and they did try to sell me insul bright instead. Boy would that have been a great Christmas gift!!