ISO 1520:2006 specifies an empirical test procedure for assessing the resistance of a coating of paint, varnish or related product to cracking and/or detachment from a metal substrate when subjected to gradual deformation by indentation under standard conditions.

For a multi-coat system, each coat may be tested separately or the complete system may be tested.

The method may be carried out as follows:

• either as a 'pass/fail' test, by testing to a specified depth of indentation to assess compliance with a particular requirement;
• or by gradually increasing the depth of indentation to determine the minimum depth at which the coating cracks and/or becomes detached from the substrate.