Quartz glass can operate normally at a temperature of 1350 ℃, with a softening temperature of 1750 ℃. The coefficient of thermal expansion of quartz glass is small, 5.5 × 10-7/℃, only 1/12 to 1/20 of ordinary glass. According to the standard, the sample should be ignited to 1200 ℃ and then quickly thrown into cold water. Repeated three times or more is not allowed to burst.