Resistance to Salt Spray

BS 3900-F4
BS 3900-F12
ISO 7253
BS EN ISO 9227
ASTM B 117

Scope and Field of Application

These tests give an indication of how well a painted surface will resist salt water spray. You may also wish to consider the prohesion test as a possible alternative. The prohesion test is a less severe version of the standard salt spray tests and is generally regarded as giving a better correlation with outdoor exposure results.

Like all laboratory tests, the methods described here have their advantages and limitations and these are summarised on our Testing Paints for Anti-Corrosive Properties page.

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

The actual standards are copyright-protected documents and we are not able to provide you with copies. If required however, you can easily obtain copies from either the American Society for Testing and Materials or the British Standards Institution.

Summary of Methods

The methods described here involve mounting the test panels in a chamber into which is introduced an aqueous solution of salt(s) in the form of a fine aerosol. The methods vary according to cabinet temperature and the composition of the salt solution.

We offer two test methods:-

Test	Summary
BS 3900-F4	This uses a mixture of salts, the proportions and concentration of which are chosen with the aim of producing artificial seawater. The cabinet is operated at 20°C.
BS 3900-F12 which is identical to ISO 7253 and virtually identical to ASTM B 117 and BS EN ISO 9227.	This uses a 5% aqueous solution of sodium chloride. The cabinet is operated at 35°C

BS 3900 Part F 12 (and its equivalents) is the more severe method and the one that is most commonly used for paint testing. In our opinion, a system with moderate corrosion resistance can be exposed for 500 hours on a scribed test panel without developing any significant under-film corrosion. The best anti-corrosive systems currently available will offer this level of protection for exposure times in excess of 2,000 hours.

Sample Requirements

The requirements are the same for all the tests. We require 3 coated panels 150 x 100 mm. The substrate should be the one that is appropriate to the type of paint being tested. We can test different size samples if required and the maximum dimensions of a single object are:-

BS 3900 Part F 4 : 150 x 400 x 500 mm
BS 3900 Part F 12 ( and equivalents) : 500 x 500 x 500 mm

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.

Accreditation

PRA is accredited to ISO 17025 by the United Kingdom Accreditation Service (UKAS) to carry out all the tests listed on this page with the exception of BS 3900 Part F 4.

Please contact Peter Collins for further details.

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