Borosilicate glass

Borosilicate glass is a type of glass with silica and boron trioxide as the main glass-forming constituents. The glass has numerous advantages over regular soda–lime glass, including being harder to break when dropped; more resistant to cracking from significant changes in temperature; having a higher clarity (transparency), which is maintained over a longer period of time; and being non-toxic, BPA-free, and resistant to chemical leaching. Borosilicate is generally slightly more expensive than soda-lime glass.

Borosilicate glasses are known for having very low coefficients of thermal expansion (≈3 × 10−6 K−1 at 20 °C), making them more resistant to thermal shock than any other common glass. Such glass is subjected to less thermal stress and can withstand temperature differentials of about 330 °F (166 °C) without fracturing. It is commonly used for the construction of reagent bottles and flasks, as well as lighting, electronics, and cookware. For many other applications, soda–lime glass is more common.

Borosilicate glass is sold under various trade names, including Borosil, Duran, Pyrex, Glassco, Supertek, Suprax, Simax, Bellco, Marinex (Brazil), BSA 60, BSC 51 (by NIPRO), Heatex, Endural, Schott, Refmex, Kimax, Gemstone Well, United Scientific, and MG (India).

Single-ended self-starting lamps are insulated with a mica disc and contained in a borosilicate glass gas discharge tube (arc tube) and a metal cap. They include the sodium-vapor lamp that is commonly used in street lighting.

Borosilicate glass usually melts at about 1,650 °C (3,000 °F; 1,920 K).

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