Which glassware is known for high thermal resistance due to its borosilicate composition?

• A. Borosilicate (Pyrex, Kimax)
• B. Aluminosilicate (Corex)
• C. High silica (Vycor)
• D. Low actinic glass

Answer: (A)

Thermal resistance in glassware comes from how much the material expands when heated. Borosilicate glass includes boron oxide in its network, which significantly lowers the coefficient of thermal expansion. That means it changes size less with temperature changes, reducing the stress that causes cracking when you move hot glass to cooler surroundings or pour hot liquids into it. That’s why borosilicate glass like Pyrex or Kimax is prized for lab glassware—it handles rapid heating and cooling much better than ordinary glass.

Other types exist, such as aluminosilicate (Corex) and high-silica (Vycor). They offer their own advantages, but they don’t match borosilicate for the common lab need of withstanding quick temperature changes. Low actinic glass is colored to filter light and isn’t chosen for its heat tolerance.