Personally, I wouldn't spray a flame retardant chemical on anything used near food, let alone in a microwave.
How are you making the bowls? Perhaps there's just something within your construction method that needs to be adjusted. Something non-cotton maybe?
Are you by any chance putting them in the microwave empty to "test" them? Guaranteed to flame if you do that. Microwave also has to have a rotating turntable.
Last edited by ghostrider; 11-18-2012 at 12:26 PM.