Corning Low Expansion Glass Pyrex

The most widely used low expansion glass is corning Pyrex®. It is mostly made from code 7740 Pyrex borosilicate glass that has been specially treated to achieve low thermal expansion. It is highly resistant to chemical attack and is able to tolerate almost all temperatures used in laboratories. It is designed for use in the tough environment requiring high resistance to strong acids, alkalis and huge thermal shock, and it is suited to applications such as mirror substrates or windows in high or low temperature environments. On the other hand, it is less homogeneous and contains more bubbles than optical glass.

The visible light transmittance of code 7740 glass is 92% at 2mm thickness. Here is a figure of internal transmittance.

	Figure 1: External transmittance curve of Pyrex at sample thickness of 2 mm

Low Expansion Materials :  

• Fused Silica
• ZERODUR®
• Corning Low Expansion Glass, Pyrex®
• ULE® titanium silica glass, VYCOR® brand glass and CLERACREAM®-Z

Pyrex® is a registered trademark of Corning Inc.