【国外标准】 Standard Practice for Performing Accelerated Outdoor Weathering of Factory-Coated Embossed Hardboard Using Concentrated Natural Sunlight and a Soak-Freeze-Thaw Procedure

5.1 The ability to quickly and accurately evaluate and predict long-term weathering performance of factory-applied coatings is of paramount importance in making sound business and technical decisions.5.2 It is important to include control specimens of known field performance to determine the efficacy of this practice for specific substrate(s) and coating system(s). These control specimens may include materials known to possess acceptable and unacceptable field performance for the defect(s) under consideration.5.3 Results derived from this practice are best used to compare the relative performance of materials tested at the same time in the same device.5.4 The inclusion of control specimens and their resulting data will assist in dealing with test variability caused by seasonal or annual variations in important climatic factors.5.5 Extensive research was performed during the development of this standard practice. This research showed that this practice is not useful for determination of quantitative acceleration factors. However, this practice is very useful for comparing the performance of different materials.5.6 A minimum of two replicates for both control specimens and test specimens is recommended to allow statistical evaluation of results. Refer to Practice G169 for additional guidance on establishing the number of replicates.1.1 This practice covers techniques to accelerate weathering effects of factory-coated embossed hardboard using Cycle 1 of Practice G90 (concentrated natural sunlight with periodic surface water spray) plus a soak-freeze thaw cycle (see Section 5 of this practice).1.2 Testing by use of the methods described in this practice may be employed in the qualitative assessment of weathering effects. The relative durability of coated hardboards may be best determined by comparison of their test results with those of control specimens derived from real time exposure test experience.1.3 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system are not necessarily exact equivalents; therefore, to ensure conformance with the standard, each system shall be used independently of the other, and values from the two systems shall not be combined.1.4 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.1.5 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.