Resistance to Cyclic Prohesion


BS 3900-F19 : ISO 11997-2
ASTM D 5894

 cyclic prohesion test cabinets

Scope and Field of Application

BS 3900-F19 and ISO 11997-2 are alternative names for the same method which is intended to measure the resistance of coatings to a defined cycle of UV radiation and salt spray.

The ASTM D 5894 test method is similar to BS 3900-F19 : ISO 11997-2 in that both are intended to simulate the effect on coatings of exposure to a salt-laden atmosphere in the presence of sunlight

Both standards state that the test cycles specified has been found useful for testing air-drying industrial maintenance coatings on steel.

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 the British Standards Institution and the American Society for Testing and Materials

 

Summary of Methods

Both methods involves the use of two different test chambers, one where the samples are exposed to UV radiation and the other where they are subjected to prohesion testing. The chambers are described on our Fluorescent Lamp Weatherometer and our Prohesion pages.

The operating conditions of the cabinets are:-

Cabinet Operating Conditions
Fluorescent Lamp Weatherometer The chamber is fitted with UVA 340 nm lamps and set to repeat a test cycle consisting of 4 hours illumination at 60° C followed by 4 hours dark / wet at 50° C.
Prohesion This uses an aqueous solution containing 0.05% sodium chloride and 0.35 % ammonium sulphate. The test cycle consists of 1 hour exposure to salt mist at ambient temperature followed by 1 hour drying at 35°C.

Both methods involve subjecting the samples to a cycle consisting of one week in the fluorescent lamp weatherometer followed by one week in the prohesion chamber. This cycle is repeated three times to give a total exposure time of six weeks (1,008 hours).

 

Sample Requirements

Ideally 150 x 75 mm coated (burnished steel) panels not more that 5 mm thick, although we can accommodate a limited number of 150 x 100 mm panels provided they are less than 5 mm thick. If you have smaller samples you can fix them to 150 x 75 mm panels provided the overall thickness does not exceed 5 mm.

The standards recommend running samples in triplicate.

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.

 

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

Please contact Peter Collins for further details.

 

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