on gas grills they use the ceramic brisquettes,and you can turn the grill up high and heat the brisquettes and then turn the heat off and the brisquettes still retain the heat for continued grilling.wondering if you heated them over a wood fire wouldn't they have the same effect as being heated with gas flame.major concern was i can't seem to find anything on max tempuratures they can be heated.wondered if anyone has every use this method,or know how much heat a ceramic brisquette can absorb