# Why doesn't stovetop glass crack from thermal shock?

I have a feeling that if my stovetop was made out of regular glass, it would have cracked from rapid cooling/heating a long time ago – especially if you consider accidental water spills. What kind of glass is able to withstand such abuse?

Stovetops are made of glass-ceramic which has extremely low thermal expansion, hence no cracking from temperature change. In fact, the coefficient is with $$0.1 \cdot 10^{-6} \ 1/K$$ even lower than that of Borosolicate glass at $$3.3 \cdot 10^{-6} \ 1/K$$. Since glass-ceramic can reach a negative coefficient of thermal expansion, getting even closer to zero is just a matter of engineering (thanks to @Volker Siegel for this interesting fact).
Borosilicate glasses (e.g. "Pyrex") have small coefficients of expansion (about $$3.3\times 10^{-6}$$/°C compared with $$10\times 10^{-6}$$/°C for steel) and can tolerate temperature differentials of about 180 °C or 330 °F.