Hardness testing methods with lower test forces (low-load and micro methods such as Vickers and Knoop) are more likely to be used for testing the hardness of non-metallic materials, such as glass or ceramics, for example in the testing of lenses or ceramic gears.
Special standards have been defined for testing the hardness of carbon (e.g. electric motor components) and plastic (e.g. artificial hip joints) test parts. Carbon testing is conducted in compliance with DIN 51917, while EN ISO 2039 applies to plastic tests.