More G Typically, these exposures would include moisture in the form of condensing humidity. Exposures are not intended to simulate the deterioration caused by localized weather phenomena, such as atmospheric pollution, biological attack, and saltwater exposure. Alternatively, the exposure may simulate the effects of sunlight through window glass.
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Test background and description: ASTM G uses a combination of fluorescent light and water to simulate exposure to sunlight and rain or dew. The sunlight exposure being simulated can either be direct or through window glass. Different UV light sources are used, depending on the type of material to be tested and conditions. For example, one lamp type is used for simulating direct sunlight or testing polymers or textiles, while another is more appropriate for simulating sunlight through window glass.
Exposure conditions can be varied through: different UV lamps, their irradiance levels, and temperature; and the timing of the light and moisture exposure. Different UV and condensation exposure cycles and temperatures can be used. A typical cycle is 8 hours UV at 60 degrees C, followed by 4 hours condensation at 50 degrees C. A typical test can run hundreds or thousands of hours. Several panels of each coating of interest can be prepared. This allows one set to be removed at each specified time interval, providing a convenient side-by-side comparison of the control and comparative or competitive panels.
Consulting on corrosion problems is also available.
Fluorescent UV (ASTM G 53)