This document specifies a test method for determining, under defined conditions, the resistance of a single coating or a multi-coat system of paint, varnish or related product to penetration, by scratching with a scratch stylus loaded with a specified load. The stylus penetrates to the substrate, except in the case of a multi-coat system, in which case the stylus can penetrate either to the substrate or to an intermediate coat.
The method specified can be carried out:
a)    either as a “pass/fail” test, by testing with a single specified load applied to the stylus to assess conformity with a particular specification; or
b)    as an assessment test by applying increasing loads to the stylus to determine the minimum load at which the coating is penetrated.
NOTE      Neither this document nor ISO 1518-2 specifies a method using a curved stylus, which is specified in ISO 12137. The choice between the three methods depends on the particular practical problem.