DIN EN ISO 16474-1:2014-03

Coatings from paints, varnishes and similar coating materials are often used outdoors or in indoor locations where they are exposed to direct solar radiation or to solar radiation filtered by glass for long periods. It is therefore very important to determine the effects of solar radiation, heat, moisture and other climatic stresses on the colour and other properties of polymers. Outdoor exposures to solar radiation and to solar radiation filtered by window glass are described in ISO 2810. However, it is often necessary to determine the effects of light, heat and moisture on the physical, chemical and optical properties of coatings with accelerated artificial weathering or accelerated artificial irradiation exposures that use specific laboratory light sources. Exposures in these laboratory devices are conducted under more uniform conditions than found in natural environments and are designed to accelerate polymer degradation and product failures. Relating results from accelerated weathering or accelerated artificial irradiation exposures to those obtained in actual-use conditions is difficult because of variability in both types of exposure and because laboratory tests often do not reproduce all the exposure stresses experienced by coatings exposed in actual-use conditions. In addition, the increase in rate of degradation by the accelerated test compared with natural exposure conditions varies with the type of material and its formulation. No single laboratory exposure test can be specified as a total simulation of actual-use exposures. The relative durability of materials in actual-use exposures can be very different depending on the location of the exposure because of differences in solar radiation, time of wetness, temperature, pollutants and other factors. Therefore, even if results from artificial accelerated weathering or artificial accelerated irradiation exposures are found to be useful for comparing the relative durability of materials exposed in a particular outdoor location or in particular actual-use conditions, it cannot be assumed that they will be useful for determining the relative durability of materials exposed in a different outdoor location or in different actual-use conditions. This part of ISO 16474 also provides information on the interpretation of results from accelerated artificial weathering or accelerated artificial irradiation exposures. The committee responsible for this standard is NA 002-00-07 AA "Allgemeine Prüfverfahren für Beschichtungsstoffe und Beschichtungen" ("General test methods for coating materials and coatings") at DIN.