Hard facts

Theory of hardness testing

Back to overview

A Knoop hardness value consists of the following components:

1. The numeric hardness value;
2. The two letters "HK", standing for "Hardness according to Knoop";
3. The applied test load in kgf;
4. According to ISO 4545: The dwell time of the test load, but only if this is not between 10 and 15 seconds (uncommon in practice)

find out more