Rubber Properties

Rubber Properties Terms Cheat Sheet

At Holz, we understand that our industry is filled with unfamiliar terms and many customers find it helpful to have a cheat sheet. We have included common sense definitions for several rubber properties below to help you understand our language.

Hardness (Durometer)

Comparative number between 20 and 90 relating to how hard (90) or soft (20) a cured piece of rubber is; there is no “standard hardness” or “common hardness”

Tensile Strength

How much does it take to break a piece of rubber; generally, higher the number is better

Modulus (tensile stress)

How much does it take to stretch a piece of rubber 2x or 3x its original length; generally, higher number is “stronger” or “stiffer”

Ultimate Elongation

How far will a piece of rubber stretch before it breaks; higher number means it will stretch farther

Tear Strength

How much does it take to tear a piece of rubber; higher number is better

Compression Set

How far will a piece of rubber come back to its original shape after it’s squeezed; generally, a lower number is better, especially in sealing applications

Resilience

How far will a rubber ball bounce; good or bad depends on the application

Weathering/Ozone Resistance

How much will the rubber compound crack if it’s outside for an extended period of time or near running electric motors for an extended period time

Permeability

How fast will a gas/vapor/liquid flow through a piece of rubber; generally, low is better

Abrasion/Wear Resistance

How much a rubber compound will be lost by any means during service