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Low Loss Borosilicate Glass (IEC 60672 Type G-231)

Low loss borosilicate is a grade of borosilicate glass. The graph bars on the material properties cards below compare low loss borosilicate to other glass and glass-ceramics (top) and the entire database (bottom). A full bar means this is the highest value in the relevant set. A half-full bar means it's 50% of the highest, and so on.

Mechanical Properties

Compressive (Crushing) Strength

2000 MPa 290 x 103 psi

Elastic (Young's, Tensile) Modulus

67 GPa 9.7 x 106 psi

Flexural Strength

34 MPa 5.0 x 103 psi

Fracture Toughness

0.8 MPa-m1/2 0.73 x 103 psi-in1/2

Knoop Hardness


Poisson's Ratio


Tensile Strength: Ultimate (UTS)

280 MPa 41 x 103 psi

Thermal Properties

Glass Transition Temperature

500 °C 920 °F

Maximum Temperature: Mechanical

360 °C 680 °F

Maximum Thermal Shock

160 °C 320 °F

Melting Onset (Solidus)

560 °C 1040 °F

Specific Heat Capacity

830 J/kg-K 0.2 BTU/lb-°F

Thermal Conductivity

1.2 W/m-K 0.68 BTU/h-ft-°F

Thermal Expansion

4.9 µm/m-K

Electrical Properties

Dielectric Constant (Relative Permittivity) At 1 Hz


Dielectric Constant (Relative Permittivity) At 1 MHz


Dielectric Strength (Breakdown Potential)

34 kV/mm 1.3 V/mil

Electrical Dissipation At 1 Hz


Electrical Dissipation At 1 MHz


Electrical Resistivity Order of Magnitude

12 10x Ω-m

Otherwise Unclassified Properties


2.5 g/cm3 150 lb/ft3

Light Transmission Range

0.3 to 2.5 µm

Refractive Index


Common Calculations

Stiffness to Weight: Axial

15 points

Stiffness to Weight: Bending

55 points

Strength to Weight: Axial

32 points

Strength to Weight: Bending

39 points

Thermal Diffusivity

0.57 mm2/s

Thermal Shock Resistance

62 points

Followup Questions

Further Reading

Dictionary of Glass: Materials and Techniques, Charles Bray, 2002

Glass: Mechanics and Technology, Eric Le Bourhis, 2007

Handbook of Optical Constants of Solids, Edward D. Palik (editor), 1998

Ceramics and Composites: Processing Methods, Narottam P. Bansal and Aldo R. Boccaccini (editors), 2012

IEC 60672-3: Ceramic and glass-insulating materials - Part 3: Specifications for individual materials