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Cupping Resistance BS EN ISO 1520 : BS 3900-E4

Scope and Field of Application

BS EN ISO 1520 and BS 3900-E4 are alternative names for the same method which is used to assess the resistance of a dry film 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. It is a particularly appropriate method for testing pre-coated metal which will be bent or extruded in some factory production process.

When choosing a test method, you may also wish to consider the mandrel bend test. Cupping is potentially a more severe test than the mandrel bend test. In the cupping test, deformation of the panel can be taken to the point where the metal fractures. This does not normally happen during mandrel tests.

The cupping and mandrel tests are all carried out on coatings applied to flexible metallic substrates. If you are interested in the flexibility or other tensile properties of coatings on different substrates, you may wish to consider tensile testing.

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

A coated metal panel is sandwiched between a hemispherical die and a hemispherical indenter. Pressure is applied to the indenter so as to form a dome shape in the panel with the coating on the convex side. The pressure is increased either to a specified depth or until the coating cracks and/or disbonds from the substrate.

There are a number of ways of examining the coating after test. We recommend using normal corrected vision but you can specify x 10 magnification if you wish.

Sample Requirements

If you wish, we can prepare the test panels. The quantity of liquid paint we needs depends on the method of application. We will be pleased to advise you regarding our requirements.

However if you wish to supply us with coated panels it is important that :-

• the thickness and composition of the substrate is such that we can deform it
• the substrate itself does not crack under test.

In practice this means that the steel or aluminium panels must be not less than 0.3 mm and not more than 1.25 mm thick. We require three panels for each coating each of which should be 100 x 150 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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