Hardness

The definition of hardness has, in the past, caused misunderstandings within the paint industry. Most coatings are viscoelastic, and hence will indent to some extent.

DIN 55 945 defines hardness as follows:
Hardness is the resistance of a coating to a mechanical force, such as pressure, rubbing or scratching.
In practice, different testing methods are used:

Wolff-Wilborn Pencil Hardness Tester
Wolff-Wilborn Pencil Hardness Tester
Buchholz Indentation Tester
Buchholz Indentation Tester
Dur-O-Test
Dur-O-Test
Pendulum Hardness Tester
Pendulum Hardness Tester
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