【国外标准】 Standard Test Method for Color Stability of Building Construction Sealants as Determined by Laboratory Accelerated Weathering Procedures

5.1 This test method is intended to induce color changes in sealants, as well as their constituent pigments, associated with end-use conditions, including the effects of sunlight, moisture, and heat. The exposures used in this test method are not intended to simulate the color change of a sealant caused by localized weathering phenomena, such as atmospheric pollution, biological attack, or saltwater exposure.5.2 When conducting exposures in devices that use laboratory light sources, it is important to consider how well the artificial test conditions will reproduce property changes and failure modes associated with end-use environments for the sealant being tested. Information on the use and interpretation of data from accelerated exposure tests is provided in Practice G151.5.3 When this test method is used as part of a specification, exact procedure, test conditions, test duration and evaluation technique must be specified. Results obtained between the two procedures may vary, because the spectral power distribution of the light sources (fluorescent UV and xenon arc) differ. Sealants should not be compared to each other based on the results obtained in different types of apparatus.5.4 These devices are capable of matching ultraviolet solar radiation reasonably well. However, for sealants sensitive to long wavelength UV and visible solar radiation, the absence of this radiation in the fluorescent UV apparatus can distort color stability ranking when compared to exterior environment exposure.NOTE 1: Refer to Practice G151 for full cautionary guidance regarding laboratory weathering of non-metallic materials.1.1 This test method describes laboratory accelerated weathering procedures using either fluorescent ultraviolet or xenon arc test devices for determining the color stability of building construction sealants.1.2 Color stability rankings provided by these two procedures may not agree.1.3 The values stated in SI units are to be regarded as the standard. Values given in parentheses are for information only.1.4 There is no equivalent ISO standard for this test method.1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.