... more than 120`C under testing 45mm thick door core, inside wall and etc. Characteristic features:1 ... %. However, the issue of rustiness in steel door or galvanized steel sheet was unable to solve ... there are plenty of tiny air hole, keeping door in good shape.6. Cost saving:The board ... widely as steel and wooden door core, partition, inside material of roof and exterior wall, prefabricated house and etc ...