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How does the thermal expansion of borosilicate glass compare with soda-lime glass?

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Borosilicate glass has a significantly lower coefficient of thermal expansion compared to soda-lime glass, which makes it much more resistant to thermal shock.123

In industrial glass chemistry, the thermal expansion coefficient is a critical factor in determining a material's ability to withstand sudden temperature changes without cracking. Typical soda-lime-silica glass has a high expansion coefficient, measured at approximately $93 \times 10^{- 7}$ per degree Celsius. In contrast, borosilicate glass—which incorporates boric oxide into its composition—exhibits a much lower coefficient of approximately $33 \times 10^{- 7}$ per degree Celsius.124

Because of this lower expansion rate, borosilicate glass is the preferred material for applications requiring high thermal durability, such as chemical laboratory glassware and domestic cookware. By replacing much of the sodium oxide used as a flux in soda-lime glass with boric oxide, manufacturers can reduce the thermal expansion coefficient to about one-third that of standard soda-lime-silica glass, thereby greatly improving its performance when subjected to rapid temperature fluctuations.23