PSA D25 1075 Paint Coatings - Crosshatch Test

The standard “PSA D25 1075 Paint coatings – Cross hatch test”, developed by the French automobile company Renault, describes a procedure for determining the resistance of a paint coating to penetration through its substrate when cuts are made through to the substrate. In general, this test should be performed on the entire system that makes up the paint film. However, the test should be performed on each layer independently to determine the specific properties of each layer.

This method is not suitable when applied to coatings with a total thickness of at least 250 μm, textured coatings and coatings with a rough surface, because the results are too scattered.

In principle, this test consists of cutting the paint film down to the substrate using a cutting tool to create a grid according to the standard “ISO 2409 Paints and varnishes - Cross-cut test” and then evaluating the adhesion of the squares of the created grid. This test is supplemented by a peel test using adhesive tape on the cross-hatched part of the film and the results are compared with a reference. This method is applied to a six-step classification.

The equipment used in these tests includes:

• Renault recommends using the Crosscut Master 3000 cross-scan device whenever the sample allows.
• Cutting tools: A single-blade cutting tool is a tool with an edge (20 to 30 degrees) as specified in the standard appendix. The use of this tool is only acceptable on parts with a bending radius too large for the correct use of the multi-blade tool. A multi-blade cutting tool is a tool with 1 cutting edges of 2 mm, 3 mm and 6 mm as specified in the standard appendix. The condition of the blades should be examined regularly with a magnifying glass. In case of doubt, a dimensional inspection should be carried out. If the blades no longer conform to the specifications in the standard appendix, they should be sharpened or replaced.
• Blade guides and spacers for single blade: This equipment is used when necessary to correctly space the cuts according to its standard attachment.
• Soft brush: It is a soft-bristled brush.
• Adhesive tape: has an adhesion of 29862 to 600 g/cm when measured according to the ISO 750 standard.
• Conditioned room: A room that does not require a hygrometer and has a temperature of 23 degrees plus/minus 2 degrees.

Test samples or specimens should be representative of the scale to be characterized. To ensure this representation, it is necessary to find out the basic characteristics of the population under study. Selection criteria for test samples or specimens should be stated in the test report in accordance with the PSA A10 0156 standard. In case of doubt about the sampling, the PSA service should be contacted to obtain the guidelines to be followed.

The dimensions of the test samples must be such that the test can be performed at three different locations on each test sample, with a minimum distance of 5 mm between these samples and the edges.

The test should also be performed on test samples taken from parts or directly from the vehicle. In the latter case, the test protocol should be adapted as much as possible and the use of a multi-blade instrument should be preferred.

The type of substrate, surface preparation, application and drying conditions of the films must be appropriate for the use of the products to be examined and must be stated in the test report. The surface of the substrate must be clean, cleaned with ethanol if necessary and wiped with a clean cloth. The thickness of the paint film must be known to an accuracy of plus/minus 10 percent or plus/minus 5 μm, whichever is less.

Test samples may be subjected to any aging specified in the standards prior to this test. Condition the test samples for at least 23 hours at 2 degrees plus/minus 16 degrees without the requirement for a moisture meter prior to testing.

If the cross-screen test is performed in addition to another test requiring special conditioning of test samples (according to standards PSA D27 1571 or PSA D27 5438), the instructions for the latter should be followed.

Among the numerous testing, measurement, analysis and evaluation studies that our organization has carried out for businesses in various sectors, it also provides testing services defined in the “PSA D25 1075 Paint coatings - Cross-hatch testing” standard with its trained and expert staff and advanced technological equipment.