Heat-resistant borosilicate glass

Special Properties

  • High-temperature resistance
  • The coefficient of thermal expansion excellently matches that of silicon (important for anodic bonding applications)
  • Good thermal shock resistance
  • Small specific weight
  • Borosilicate glass composition

Typical Applications

  • PYREX® wafers for anodic bonding
  • Substrates for dielectric coatings
  • Heat shields
  • Chemically resistant glass covers
  • Neutron absorbers
  • High-temperature environments
  • Sensor technology
  • Applications in science, research, and development
  • Harsh Environments
  • Material for chemical laboratory equipment

Related glass types

PYREX® is a borosilicate glass from CORNING with excellent thermal properties. A low expansion coefficient of only about one-third of that of soda-lime glass materials ensures high thermal shock resistance. PYREX® material has been used to manufacture temperature-resistant optics for a long time.

PYREX borosilicate glass raw blocks nullspacer

Unprocessed PYREX® borosilicate glass comes in unpolished large blocks or as rolled sheets. We can grind, polish, and further process these materials to meet customer-specific requirements.

Glass wafers made of PYREX® are a standard for the semiconductor industry. They are a perfect solution for the anodic bonding of glass to silicon because the thermal expansion of PYREX® borosilicate glass closely matches that of silicon.

A much better chemical resistance than soda-lime materials and PYREX unpolished borosilicate glass raw material from Corning exquisite optical transmission over a wide wavelength range made PYREX® a versatile option for many optical applications that were not possible with ordinary soda-lime glass. PYREX® is ground, polished, shaped, and coated according to customer requirements.



PYREX® rolled sheets and block glass were discontinued many years ago. However, CORNING released PYREX SG3.3 in the meantime, now available in thicknesses of 0.3–2.3 mm. Please send us your inquiry if you are interested in more details about this new PYREX® borosilicate glass version.


Please use the button below to request a quotation for windows, substrates, wafers, or other optics made of PYREX® with individual dimensions.


Get a Quote


Please look at our quartz and fused silica materials for higher-temperature requirements. Moreover, fused quartz with sight-glass quality is available.



PYREX® Transmission at 2 mm thickness

Transmissivity of PYREX®

Enlarge the curve to show details

Glass Thicknesses

Since PYREX® is not available as blank sheet glass, there are no standard thicknesses. The thickness must, therefore, always be specified individually.

Refractive Index

  • nd = 1.474 (588 nm)


  • 2.23 g/cm3

Coefficient of Thermal Expansion (0–300 °C)

  • 3.25 × 10-6

Young's Modulus

  • 6400 kg/mm2

Dielectric Constant

  • 4.6 (20 °C ; 1 MHz)

Loss Factor

  • 0.5% (20 °C ; 1 MHz)

Further detailed glass specifications are available on request.

All given details and specifications are mean reference values and are not guaranteed. Also, please consider our "Notes on technical specifications".

© 1994 – 2024 Präzisions Glas & Optik GmbH

Last update: May 21, 2024