Borosilicate Glass is well-known for its durability, low coefficient of expansion, low density, high softening point, high resistance to acids and thermal shock, compared to other glass formulations. The chemical composition consists primarily of silicon oxide (SiO₂) and boron oxide (B₂O₃). Coefficient of thermal expansion for borosilicate glass is about one third of other glass compositions making it resistant to thermal shock, which is critical for those applications where minute deviations in shape might matter.

Specific physical properties vary by product and lot number. The numbers below are general for borosilicate glass and to be used for reference only:

• True Particle Density: ~2.2g/cc
• Index of Refraction: ~1.48
• Annealing Temperature: ~560C
• Softening Temperature: ~820C
• Thermal Expansion: ~30x10^-7/C
• Chemical Resistance: resistant to corrosive environments