Polyurethane elastomers made with Air Products' prepolymers can be formulated to cover a wide range of hardness, from soft rubbers to rigid plastics. The following Hardness Table shows the spectrum of hardness values possible and a few examples from the correspondingly wide range of applications.

Test Procedure to Measure Hardness ASTM Method D676

The hardness of an elastomer is determined with a durometer. This instrument measures resistance to the penetration (without puncturing) of a blunt indenter point pressed onto the elastomer surface against the action of a spring. A pointer moves across a scale to show the resistance to penetration. Scales on the Shore durometer read from 0 to 100, with higher numbers denoting greater hardness. Two scales are commonly used for elastomers: the "A" scale for soft materials, and the "D" scale for materials of higher hardness. These scales do overlap, as shown in the Hardness Table.