ASTM G155 Accelerated Weathering (Xenon Arc)
Standard: ASTM G155 Standard Practice for Operating Xenon Arc Lamp Apparatus for Exposure of Materials
Scope: ASTM G155 is intended to reproduce the weathering effects that occur when materials are exposed to sunlight (either directly or through window glass) and moisture as rain or dew in actual usage. The standard is intended to be used in conjunction with a practice or method that defines specific exposure conditions for an application along with a means to evaluate changes in material properties (e.g. color fade resistance; resistance to cracking, crazing, or other surface degradation; change in tensile or flexural properties).
No direct correlation has been made between accelerated weathering duration and actual outdoor exposure duration. Additionally, exposures are not intended to simulate the deterioration caused by localized weather phenomena, such as atmospheric pollution, biological attack, and saltwater exposure.
Products: Many different products and materials can be exposed per ASTM G155, including, but not limited to: paints/coatings, polymers/plastics, rubber, fabrics/textiles, wood-plastic composite deck boards, water-resistant barriers (WRBs), sealants, roofing materials, and vinyl siding.
Procedure: Specimens are exposed to accelerated weathering through repetitive cycles of light and moisture under controlled environmental conditions. Moisture is typically produced by condensing water vapor onto the test specimen or spraying the specimens with demineralized/deionized water. The exposure condition may be varied by selecting: filter type; the lamp’s irradiance and wavelength; the moisture exposure; the timing of the light, dark, and moisture periods; and the temperature.
Result: ASTM G155 is limited to the basic principles for operating a xenon arc weathering apparatus; on its own, it does not deliver a specific result. Most often, another test is conducted in follow-up to the ASTM G155 exposure, like a visual observation, tensile test, or bending test. A control specimen may also be tested in order to provide a reference for comparative purposes.