Optical Glass picture

PYREX® Borosilicate Glass

Temperature resistant technical glass

Special Properties

  • High thermal resistance
  • Low thermal expansion
  • Good thermal shock resistance
  • Thermal expansion matches silicon (anodic bonding)
  • Low specific weight

Typical Applications

  • Substrate for dielectric coatings
  • PYREX® Wafers for anodic bonding
  • Sensor substrates
  • Heat shields
  • Neutron absorbers
  • High temperature applications
  • Harsh environments
PYREX raw glass blocks PYREX® comes in unpolished glass blocks or as rolled material. It can be sawn, ground, polished and shaped according to customer-specific requirements.

PYREX® is a technical borosilicate glass composition from Corning with excellent thermal properties. A low coefficient of thermal expansion allows a good heat shock resistance and facilitates the use of PYREX® glass at high operating temperatures. Wafers made of PYREX are an ideal solution for PYREX unpolished raw materialanodic bonding processes, because the thermal coefficient of expansion almost perfectly matches to silicon. A good acid resistance and a high optical transmission over a wide wavelength range make PYREX a versatile material for many different special glass applications. PYREX can be ground, polished and coated according to custom specific requirements.

To request windows or substrates made of PYREX® borosilicate glass with individual dimensions, please click the button below:

Request for PYREX quotation


The production of PYREX® raw materials has been discontinued many years ago. There is only a small material stock left, so large quantities cannot be quoted based on this material anymore. Nevertheless we have equivalent or superior grade borosilicate glass materials available that feature an almost identical glass composition and almost identical specifications. Please send us your inquiry. We will be pleased to assist you in the selection of the right material for your application.


Show transmission curve of PYREX®

Refractive Index

  • nd = 1,474 (588nm)


  • 2,23g/cm3

Coefficient of Thermal Expansion (0-300°C)

  • 32,5 x10-7

Young's Modulus

  • 6400 kg/mm2

Dielectric Constant

  • 4,6 (20°C; 1Mhz)

Loss Factor

  • 0,5% (20°C;1Mhz)

Further detailed specifications on request.

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