Durometer Explained

A durometer is a gauge instrument for testing the hardness of various plastics & rubber. ASTM D2240 Standard Test Method for Rubber Property, Durometer Hardness.   Hardness is the resistance to surface penetration. Lower numbers indicate softer, more flexible materials, while higher numbers indicate harder and typically more durable materials. Along with the number there is usually an alpha scale rating with “A” being softer materials and “D” for harder materials. See the figure below.

Durometer is important because you can determine how much the material will compress. Knowing how much it will compress will let you determine how much material displacement you will get which can form a seal. Maybe you are going to have a lot of force clamping together and you need a high durometer material to not squeeze too much.

If you want help picking the right amount duro for your application, please feel free to contact an Application Engineer at (602) 437-1532 or email us at info@stateseal.com.