Class 1A and Class 1B
Class 1A and Class 1B silicones are best for extreme low temperature environments, defined as -73°C (-100°F). These silicones can also handle high temperatures, up to 219°C (425°C), but they don’t last as long as Class 2 materials when consistently exposed to heat in service. At high temperatures, Class 1B silicones have low compression set.

Class 2A and Class 2B
Class 2A and Class 2B silicones are best for high temperatures, up to 219°C (425°C). They have less low temperature resistance than Class 1 silicones and generally can’t resist temperatures lower than -62°C (-80°F). Class 2B silicones have low compression set.

Class 3A
Class 3A silicones are resistant to tearing, flexing, and extreme temperatures ranging from -75°C (-103°F) to 204°C (400°F). Common applications for Class 3A silicones are exhaust hangars and engine mounts.

Class 3B
Class 3B silicones share many properties with Class 3A, including excellent resistance to tearing, flexing, and high heat. However, Class 3B’s low temperature resistance range is limited to -70°C (-95°F). Common applications for Class 3B silicones include vibration mounts and seals for windows and aircraft doors.

Please note: The information outlined above is to be used as a reference for A-A-59588. Please refer to GSA for full details and the most current revision.