... 900°C for 15 minutes, then put into20°C water 3 times, no crack. Opaque/Milky quartz glass ... 2.2-3.5 micron3. Health care & environmental protection4. Can be work in vertically and horizontally5. with highly heat ... long term used under 1200°c7. 6000h service life, with SGS, RoHs approved8. Widely used in infrared heater, cooking, oven, ... infrared heating element FYI electrical milk heater with CE