General Borosilicate Glass



Borosilicate glasses have a remarkably low coefficient of thermal expansion and are therefore very resistant to thermal shock. Their main glass-forming constituents are substantial amounts of silica and boron trioxide. Usually, one distinguishes between non-alkaline earth borosilicate glass, alkaline-earth-containing borosilicate glass and high-borate borosilicate glass.

Ashby charts

See where falls on the material property chart for Density against Elastic modulus in your materials selection and design process.



Density ρ

2.1 - 2.8 g/cm³ at 20 °C


Elastic modulus E

50 - 70 GPa at 20 °C

Hardness, Knoop, HK2 HK2

400 - 480 [-] at 20 °C

Poisson's ratio ν

0.2 - 0.22 [-] at 20 °C

Shear modulus G

26.5 - 27 GPa at 20 °C


Annealing temperature Tanneal

470 - 640 °C

Coefficient of thermal expansion α

3.2E-6 - 7.38E-6 1/K at 300 °C

Glass transition temperature Tg

440 - 560 °C

Thermal conductivity λ

0.96 - 1.2 W/(m·K) at 20 °C

Vicat softening temperature Tsoft

460 - 840 °C


Dielectric constant εr

4.1 - 6.7 [-] at 20 °C

at 1MHz

Loss tangent tanδ

6E-5 - 0.01 [-] at 20 °C

at 1MHz


Refractive index nd

1.47 - 1.52 [-]

This material data has been provided by Matmatch.

All metrics apply to room temperature unless otherwise stated. SI units used unless otherwise stated.
Equivalent standards are similar to one or more standards provided by the supplier. Some equivalent standards may be stricter whereas others may be outside the bounds of the original standard.