The Knoop test allows measuring of the hardness of fragile materials such as glass and ceramics or deposits of low thickness.

The indenter consists of a pyramid-shaped diamond with a rectangular base. The first angle is 172°30′ between two opposite sides and 130° for the other two sides.

The applied loads are less than 1 kgf.

If the length and width of the indentation is measured using a microscope, the Knoop hardness (HK) is given by the following formula:
Diagram of the calculation of the Knoop hardness
PRESI offers a range of Knoop Hardness Testers and accessories that facilitate hardness/micro-hardness testing. Our range is differentiated between the mechanical weight range (the Matzuzawa Microtech and Macrotech testers) and the load cell range (the HZ Hardness Testers).


MATSUZAWA MX7 and MX7 low loads

HZ automatic and semi-automatic