Exposure Testing

There are many factors to consider when selecting a weathering test station to conduct a test program. These can be summarized into two categories:

• Location: An ideal test site should be located in a clean pollution free area, if pollution is not deemed to be a parameter, within the geo-climatic region to be used. This is important for the prevention of unnatural effects on the specimens. Within the local area chosen, there must be no isolated sources of pollution or deleterious atmospheric contamination.
• Maintenance: The exposure maintenance program followed by the test site will also play a major role in determining the accuracy of testing. It is important for the specimens on the test racks to be correctly maintained. This involves ensuring the correct mounting method, and constant follow-up attention to maintain the quality.

For direct exposure the specimen is mounted on the exposure frame open backed or solid backed, and subject to all atmospheric effects. This type can be used at a number of exposure angles. The standard angles used are 45, 5, and 90 degrees, these angles being referenced from a horizontal angle of 0 degree. The angle chosen should be one that matches as closely as possible the position of the end use of the material. The racks should be cleaned on a regular basis to remove mildew and algae if these contaminate producers are present on the test site.

To see a picture of the rural marine atmosphere exposure rack at Dockyard Laboratory (Pacific), 'click here'.