BACKGROUND
In Hardness Testing, Hardness is determined by measuring the comparative depth of two carefully controlled indentations, one superimposed over the other.
First a minor load (one of a lesser force) is applied to a steel ball or sphero-conical diamond penetrator. Then while the minor load is-still being applied, a major load (one of greater force) is applied at a precisely controlled rate. The major load is removed and the hardness determination is obtained, this represents the additional depth to which the major load has indented the test specimen beyond the initial indentation.
The displayed indentation is proportionally inverse.