Elastomer Durometer Information

Elastomer Durometer Information

Durometer is a measure of the hardness of a material, defined as the material’s resistance to permanent indentation.:


Type 1   =   Open Cell

Type 2   =   Closed Cell



Class A  = Non-oil resistant

                  (Example: EPDM)

Class B  =  Oil resistant, low swell

                  (Example: Nitrile)

Class C  =  Oil resistant, medium swell

                  (Example: Neoprene)

Class D  =  Extreme Temperature resistant

                  (Example: Silicone)



Grade ratings represent compression deflection, or the amount of force in pounds per square inch to deflect the sample 25% of its height.


Grade 0     =      less than 2 psi

Grade 1     =      2 to 5 psi

Grade 2     =      5 to 9 psi

Grade 3     =      9 to 13 psi (for Classes A, B, C)
                        9 to 15 psi (for Class D)

Grade 4     =      13 to 17 psi (for Classes A, B, C)
                         22 to 30 psi (for Class D)

Grade 5     =      17 to 25 psi (for Classes A, B, C)
                         22 to 30 psi (for Class D)



Suffix numbers that follow the suffix letters denote different testing parameters or conditions for that suffix.  Once testing is complete, a Line Call Out is assigned to the compound according to the Basic and Suffix requirements the compound has met.



A             Heat Resistance

B             Compression Set

C             Ozone or Weather Resistance

D             Compression Deflection Resistance

E             Fluid Resistance

F             Low Temperature Resistance

G             Tear Resistance

J              Abrasion Resistance

K             Adhesion Resistance

L              Water Absorption

M             Flammability Resistance

N             Impact Resistance

P             Staining Resistance

R             Resilience

W            Density

Z             Any Special Requirements


Example Line Call Out for Sponge

ASTM S1056 2C2 A1 B2 E1 Z
 (z= Material Passes FMVSS 302)