... 900°C for 15 minutes, then put into20°C water 3 times, no crack. Opaque/Milky quartz glass ... used under 1200°c7. 6000h service life, with SGS, RoHs approved8. Widely used in infrared heater, cooking, oven, stove, baker, painting ... of quartz electrical milk heater :package of electrical milk heater our factoryproduction lineother infrared heating element FYI electrical milk heater with CE