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Natural Weathering
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Scope and Field of Application
Natural weathering of paints and similar materials involves exposing test panels outdoors at appropriate locations. These locations can be chosen on the basis of climate ( eg tropical, temperate, desert ) or on the basis of atmospheric pollution ( eg rural, industrial, marine).
The advantages and limitations of artificial weathering are summarised, in general terms, on our Testing Paints for Resistance to Weathering page. Natural weathering has the single important advantage that, for a given location, it provides the most reliable data on how a coating will perform in service. There are however a number of disadvantages:-
- if the coatings under test are highly durable, it can take years to obtain sufficient degradation to enable them to be differentiated.
- climatic variation are such that no two years are the same and consequently you can never reproduce the results you obtain.
- the results obtained using small test panels are likely to differ from those obtained when large structures are painted.
BS EN ISO 2810 is essentially a guidance note for the conduct of natural weathering tests. 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 a copy from the British Standards Institution.
Summary of Method
We follow the general principles of BS EN ISO 2810 and we can expose test panels at rural, urban, industrial and marine sites. We can, if required, monitor the exposure conditions at regular intervals for:-
- air temperature
- black panel temperature
- humidity
- time-of-wetness
- rainfall
- UV-A
- UV-B
- total solar radiation
We recommend that the panels are assessed every six months. Normally we would rate the coatings for blistering, chalking, cracking, flaking, microbial growth and (if on steel) for rusting. There are however a number of additional tests that can be carried out and these are detailed on our Testing Applied Paint Films page. You have to bear in mind that for most of these additional tests, the panels have to be returned to our laboratory. Some of these laboratory tests are destructive so it is necessary to have sufficient panels on exposure to allow for this.
Sample Requirements
BS EN ISO 2810 requires that each test panel shall have an area of at least 300 square cm and that no side should be less than 10 cm in length. We normally use 10 x 30 or 15 x 20 cm panels (4 x 12 or 6 x 8 inch). We recommend that panels should be exposed in triplicate together with extra panels, if required, to allow for any destructive testing.
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 this test.
Please contact Peter Collins for further details.
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