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Assessment of Blistering BS 3900-H2 : ISO 4628/2

Scope and Field of Application

BS 3900-H2 and ISO 4628/2 are alternative names for the same method. It is one of a series of methods of designating the quantity and size of common types defects in paint coatings. Other methods in this series deal with the assessment of chalking, cracking, flaking and rusting.

There are no pass/fail criteria defined in the standard. This is a matter of agreement between the parties concerned.

The actual standard is a copyright-protected document and we are not able to provide you with copies. If required however, you can easily obtain copies from the British Standards Institution.

Summary of Method

It is important to emphasise that the standard describes a method of assessing blistering. It is not a method for testing the resistance of a coating to blistering. If you need to test for resistance to blistering, then please refer to our corrosion and durability pages and in particular to humidity testing. We will of course be pleased to advise on the most appropriate test for your samples.

The standard is basically a collection of photographs of test panels showing blisters that vary in both size and density. The photographs are rated for both size and density using four-point scale ranging small/few to large/dense blisters. The sample is compared with these photographs and given the rating of the photographs that bear the closest resemblance.

Sample Requirements

This assessment is normally carried out using test panels that have been subject to some form of corrosion or durability testing and the panel size and number will have been selected for that purpose. Basically all we need is a representative test piece with an area for assessment of at least 100 x 100 mm.

Accreditation

PRA is accredited to ISO 17025 by the United Kingdom Accreditation Service (UKAS) to carry out this test.

 

Please contact Peter Collins for further details.

 

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