. "The insulation used on the first and second faces 18, 20 may be thermally non-conductive paints or coatings such as ceramic; or a fluorocarbon resin such as polytetrafluoroethylene (PFTE), fluorinated ethylene propylene (FEP), or perfluoroalkoxy (PFA), all of which are known as Teflon???, available from DuPont de Nemours; or other thermally insulative materials as are known in the art." . . .