The ‘Knoop hardness test’ method is one of the micro hardness tests –
Tests for mechanical hardness used particularly for very brittle materials or thin sheets, where only a small indentation may be made for testing purposes.
The Knoop and Vickers techniques are called micro-indentation-testing methods based on indenter size.
Both are well suited for measuring the hardness of small, selected specimen regions; furthermore, the Knoop technique is used for testing brittle materials such as ceramics.