MACOR® Machinable Glass Ceramic has a continuous use temperature of 800°C and a peak temperature of 1000°C. Its coefficient of thermal expansion readily matches most metals and sealing glasses. It is nonwetting, exhibits zero porosity, and unlike ductile materials, won't deform. It is an excellent insulator at high voltages, various frequencies, and high temperatures. Machining tolerances: detail machining to .0005"; surface finish of less than 20µin and polishing to a smoothness of 0.5µin.-AA.