Borosilicate is the most common and most cost-effective of the technical glass materials on the market, making it a frequent choice for low-cost component manufacture.


Relative Cost of Material


Machining Degree of Difficulty


Borosilicate glass, comprised primarily of Silica and Boron Trioxide, is a generic term that covers many subgroups of glass materials. Since its development by Otto Schott (the founder of Schott glass) back in the late 1800s, borosilicate is knwn for having superior thermal shock resistance and a lower CTE than glass commonly used in non-technical settings. This has many advantages, one of which being that it allows for glass-to-metal seals to be made with materials of similar CTE, such as Kovar or Molybdenum.

Mindrum Precision has been grinding, polishing, and machining components out of borosilicate for over sixty years, as this was the original core competency that our company was founded on. We not only machine borosilicate on a daily basis, but we treat it like many high-precision shops treat aluminum, where we will make setup pieces for components made from other optical materials with difficult geometries out of borosilicate to test our process and improve our accuracy while minimizing cost to our customers. Click here for our contact information, and let us show you why so many engineers have trusted us with their mission-critical needs.


As a low-cost optical material, borosilicate is found in all types of technical and non-technical products. From precision optics and aerospace applications to lighting and cookware, this is an industry standard that has many, many uses. 


Material PropertyBorosilicate
Density (g/cm^3)2.2
Hardness (Knoop)418
Tensile Strength (MPa)32
Modulus of Elasticity (GPa)64
Compressive Strength (MPa)246 - 384
Poisson's Ratio0.2
Dielectric Strength (ac-kV/mm)12
Dielectric Constant (@1MHz)4.6
Volume Resistivity (ohm-cm @25°C)8.0E10
Coefficient of Thermal Expansion (1 x 10^-6/°C)3.3
Thermal Conductivity (W/m K)1.35
Specific Heat (J/kg*K)830
Maximum Working Temperature (°C)500
Index of Refraction1.47
*Note: Properties vary by manufacturer. The above information should be used for general reference purposes only.

related Materials

  • Fused Quartz – A lower purity, most cost-effective form of Fused Silica
  • KovarA Nickel-Cobalt alloy with similar CTE that can be bonded with many borosilicate components 
  • N-BK7 and BK7 – Excellent optical properties, frequent choice for windows and prisms