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How to Test Plastic Properties
Durometer Hardness instrument has a pointed indenter projecting below the base (face) of the pressure foot. When the indenter is pressed into the plastic specimen so that the base rests on the plastic surface, the amount of indentation registers on the dial indicator.
This test measures the indentation into the plastic of the indenter under load, according to a scale of 0 to 100. There is no unit of measurement. Readings taken immediately after application may vary from those taken after pressure has been held for a time, because of creep. This test is preferred for polyethylene, because the Rockwell test loses meaning when excessive creep is encountered. For other materials (acetate, acetal, etc.) the Rockwell hardness test is still the standard. ASTM D-1706.