Paints and Varnishes - Cross-Cut Test
|Publication Date:||1 January 1992|
|ICS Code (Paints and varnishes):||87.040|
This International Standard is one of a series of standards dealing with the sampling and testing of paints, varnishes and related products. It specifies a test method for assessing the resistance of paint coatings to separation from substrates when a right-angle lattice pattern is cut into the coating, penetrating through to the substrate. The property measured by this empirical test procedure depends, among other factors, on the adhesion of the coating to either the preceding coat or the substrate. This procedure is not to be regarded, however, as a means of measuring adhesion.
Where a measurement of adhesion is required, attention is drawn to the method described in ISO 4624:1978, Paints and varnishes - Pull-off test for adhesion.
NOTE 1 Although the test is primarily intended for use in the laboratory, the test is also suitable for field testing.
The method described may be applied either as a pasclfail test or, where circumstances are appropriate, as a six-step classification test (see 8.3). When applied to a multi-coat system, assessment of the resistance to separation of individual layers of the coating from each other may be made.
The test may be carried out on finished objects and/or on specially prepared test specimens.
Although the method is applicable to paint on hard (steel) and soft (wood and plaster) substrates, these different substrates need a different test procedure (see clause 7).
The method is not suitable for coatings of total thickness greater than 250 µm or for textured coatings.
2 Coatings with a total thickness of over 250 µm may be tested by means of a single cross-cut.
3 The method, when applied to coatings designed to give a rough patterned surface, will give results which will show too much variation.