This sheet of the standard gives requirements for several types of rigid mica materials based on mica splittings or mica paper for application in electrical heating equipment. These products may be made from muscovite or phlogopite mica with a suitable bonding medium. The binder may be totally driven off in service, giving a material which needs to be supported, or may remain totally or partially, giving a self-supporting material; in this case, the binder shall have the necessary resistance to the operating temperature. The products may be supplied in sheets, strips or flat pieces. The minimum nominal thickness is 0.30 mm (mica splittings) and 0.20 mm (mica paper).