Borosilicate glass

Borosilicate glass is a type of glass with the main glass-forming constituents silica and boron oxide. Borosilicate glasses are known for having very low coefficients of thermal expansion (~3 × 10 /°C at 20°C), making them resistant to thermal shock, more so than any other common glass. Such glass is less subject to thermal stress and is commonly used for the construction of reagent bottles. Borosilicate glass is sold under such trade names as Kimax, Pyrex, Endural, Schott, or Refmex.

In coffee brewing, thermal shock is a problem because hot water is poured into beakers and other recipients. Manual coffee brewing devices made of glass can easily break because of the thermal shock. Borosilicate glass is used for manufacturing the French press, Chemex beakers, carafes, coffee mugs, glass coffee cups, and glass espresso cups, as well as all recipients that come in contact with hot water, or coffee.