What is ISO 4624 - Pull off test in paints standard about?

The adhesion of a coating or several coated samples of any paint product is measured by assessing the minimum tensile stress needed to detach or rupture the coating perpendicular to the substrate. ISO 4624 is one of two standards which describe methods for assessing the adhesion of a single coating or a multi-coat system of paint, varnish, or related product by measuring the minimum tensile stress necessary to detach or to rupture the coating in a direction perpendicular to the substrate.

The test result is influenced not only by the mechanical properties of the system under test but also by the nature and preparation of the substrate, the method of paint application, the drying conditions of the coating, the temperature, the humidity and other factors like the type of test instrument which has been used. ISO 4624 specifies three methods (i.e. one dolly or two dollies on a painted panel and two dollies, one as painted substrate) for determining the adhesion by carrying out a pull-off test on a single coating or a multi-coat system of paint, varnish, or related product.

Who is ISO 4624 - Pull off test in paints standard for?

ISO 4624 on pull off test in paints standard is useful for:

Manufacturers of paints and varnishes
Product development teams
Quality control teams

Why should you use ISO 4624 - Pull off test in paints standard?

How well paint sticks to a substrate depends on the interaction between the two materials during the application. The strength of the bond between the substrate and the paint dictates how well it will withstand the characteristics of its immediate surroundings. Implications of adhesive strength are not easily observable by the naked eye.

Therefore ISO 4624 test methods have been found useful in comparing the adhesion behaviour of different coatings. ISO 4624 is most useful in providing relative ratings for a series of coated panels exhibiting significant differences in adhesion.

ISO 4624 test may be applied using a wide range of substrates. Different procedures are given according to whether the substrate is deformable, for example, thin metal, plastics, and wood, or rigid, for example, thick concrete and metal plates. To avoid distortion of the substrate during the tensile test, it is common to use a sandwich construction. For example, for special purposes, the coating may be applied directly to the face of a test dolly.

ISO 4624 provides you with guidelines on test panels in terms of substrate, preparation, and coating, drying and conditioning as well as thickness of coating. In addition, ISO 4624 also gives you details on procedure and calculation, and expression of results. Using ISO 4624 guidelines, you can determine the adhesion by carrying out a pull-off test on a single coating or a multi-coat system of paint, varnish, or related product. ISO 4624 guidelines enable you to provide your customers with suitable, reliable, and high-quality coatings.

What’s changed since the last update?

BS EN ISO 4624:2016 supersedes BS EN ISO 4624:2003. BS EN ISO 4624:2016 includes some technical changes with respect to BS EN ISO 4624:2003. These include:

Detailed information on how to avoid distortion of the substrate during the tensile test has been added
The three methods using one dolly or two dollies on a painted panel and two dollies, one as painted substrate, have been named methods A, B, and C
The supplementary test conditions previously in Annex A have been integrated in the test report

BS EN ISO 4624:2016

Paints and varnishes. Pull-off test for adhesion

Published:

30 Apr 2016

Withdrawn:

23 Jun 2023