Hardness is one of the most important properties which determine the suitability of any rubber component for its intended end use. Incorrect hardness may defeat the basic purpose for which the component is designed.

Thus accurate and reliable determination of hardness is of extreme importance in rubber field. Amongst the various means for the determination of rubber hardness the most important ones are the Durometer and the IRHD Hardness Tester. While the first uses the principle of indentation of a truncated cone in rubber under varying loads acting through a spring, the second method uses a fixed dead load acting on a hemispherical indenting tip.

Whereas the first method suffers from the disadvantage of permanent set getting developed in the spring and thus affecting its accuracy, the second method, being based on dead load principle, is free from this problem.