Outdoor testing is essential for the validation of accelerated testing.
Currently, all weathering testing is done using either an outdoor exposure location or indoor accelerated testing equipment. These two major test types are not the same. Accelerated tests are made with controlled, artificial light sources in the laboratory, whereas natural weathering is performed in large outdoor fields with real sunlight but where all the exposure parameters are not controlled. Table 1 gives a comparison of outdoor and accelerated tests. The choices that are laid before us are whether to use the fast, controlled exposure that uses simulated conditions, or the slow, non-controlled test that is known for its realism. For many, the choice has been to pick speed over substance.