[China Aluminum Industry Network] 1 Introduction The GB 5237.3-2008 standard, titled "Aluminum Alloy Building Profiles – Part 3: Electrophoretic Coating Profiles," was primarily based on GB/T 8013-2007 and referenced Japanese JIS H8602-1992 and U.S. AAMA 612-02 standards at the time of its development. During its formulation, the performance requirements and indicators were already on par with or even exceeded those of JIS H8602-1992. It also introduced additional criteria for hydrochloric acid and mortar resistance, tailored to the specific construction environments in which these profiles are used. However, since then, Japan has revised JIS H8602 to the 2010 version, significantly enhancing its performance requirements. Additionally, the ISO proposal for aluminum anodized electrophoretic coating composite films has also undergone continuous revisions. This article provides a concise comparison of the key differences between China's GB5237.3-2008 standard, Japan's JIS H8602-2010 standard, and the corresponding ISO proposals. 2 Key Differences Between China’s GB5237.3-2008 and Japan’s JIS H8602-2010 and ISO Proposal 2.1 Weather Resistance Weather resistance is a crucial performance indicator for architectural electrophoretic aluminum alloy profiles. Both the Japanese standard and the ISO proposal classify artificial accelerated weathering tests using xenon lamps into four levels: 350h, 1000h, 2000h, and 4000h. In contrast, China’s GB5237.3-2008 divides the test times into three grades: 1000h, 2000h, and 4000h. Notably, China’s standard does not include the 350h test, which is present in both the Japanese and ISO proposals. However, the other three levels align with those of the Japanese and ISO standards. Although the three standards have similar weather resistance requirements, they differ in specifying the usage environment for the composite film. China’s standard outlines weatherability requirements but does not clearly define where the film should be applied. In contrast, Japan’s JIS H8602-2010 and the ISO proposal provide guidance on the appropriate use conditions. For instance, it recommends that a 350h test film be used indoors, a 1000h test film for normal outdoor environments (such as cities and industrial areas), a 2000h test film for harsh outdoor environments (like coastal areas), and a 4000h test film for seaside or high UV exposure areas. These recommendations are practical and help customers select the appropriate grade of coating. 2.2 Corrosion Resistance Unlike China’s standard, Japan’s JIS H8602-2010 and the ISO proposal specifically address joint corrosion resistance by combining fluorescent UV lamp testing with salt spray testing. This approach reflects real-world conditions more accurately. Several factors contribute to this difference. First, from an operational perspective, weather resistance tests can take thousands of hours, which many manufacturers find impractical. Second, from a practical standpoint, using a 313nm UV lamp with irradiation intensity of 30 W/m², followed by 4 hours of drying and 4 hours of wet cycles for 240 hours, and then performing a CASS test, better simulates real-world exposure to UV radiation, acid rain, and pollutants. Third, from a coating perspective, UV exposure for 240 hours mimics short-term aging. If unstable monomers are used, the test becomes difficult to pass. Therefore, selecting long-chain acrylic monomers improves light stability and reduces chalking. Finally, from a microscopic perspective, shorter wavelengths (e.g., 340nm) carry higher energy, making them more effective in detecting stable coatings. If the coating withstands UV exposure without degradation, it will perform well in subsequent corrosion tests. 3 Other Important Considerations in the Standard 3.1 Hardness Coating hardness is a fundamental performance metric. Two common methods are indentation hardness and pencil hardness tests. Due to the thin nature of electrophoretic coatings, China’s GB5237.3-2008 and the ISO proposal use the pencil hardness test, while Japan’s standard does not specify it. China requires Class A and B coatings to be at least 3H, while Class S must be at least 1H. The ISO proposal mandates all coatings to be at least 3H. Pencil hardness depends on the coating material, curing level, and thickness. Thinner coatings tend to be harder. 3.2 Gloss Neither China nor Japan specifies gloss in their standards, though the ISO proposal outlines a method for measuring it. Gloss is typically measured with a 60-degree gloss meter, and multi-angle meters may be used for more detailed results. The surface must be flat, with a flatness of 0.18 or less. 3.3 Adhesion All three standards require adhesion to reach 0 (25/25). Cross-cutting is commonly used, and the tool must be sharp to expose the metal substrate. After water immersion, the adhesion test simulates the impact of rainwater. Poor adhesion indicates poor bonding between the coating and the substrate. 3.4 Salt Spray Corrosion Resistance Three main salt spray tests exist: NSS, AASS, and CASS. CASS is the most aggressive. China’s standard only allows 24h and 48h tests, while Japan and the ISO propose 24h, 72h, and 120h tests, especially for coastal areas. The latter is more stringent. 3.5 Alkali Resistance All three standards have similar alkali resistance requirements, tested at 20°C. However, under certain conditions like heavy rain and pollution, additional tests such as boiling water resistance may be needed. Different resins can affect the results. 3.6 Composite Film Thickness Japan’s new standard requires an oxide film thickness of at least 5μm, but in practice, companies often exceed 8μm. Electrophoretic film thickness also affects properties like CASS and weather resistance. While Japan’s new standard focuses on performance rather than thickness, this has caused concern among paint manufacturers. 3.7 Natural Weather Resistance Natural weathering is critical for electrophoretic coatings, as buildings are expected to last as long as their structures. China’s standard and the ISO proposal mention natural weathering, but the details are not clear. While lab-based accelerated tests are useful, they may not fully reflect real-world durability. Therefore, studying natural weathering is essential for improving coating performance. 4 Conclusion Although there are still differences between China’s GB5237.3-2008, Japan’s JIS H8602-2010, and the ISO proposals, we believe that with the advancement of industry and globalization, China will continue to improve its standards, reduce gaps with international benchmarks, and ultimately develop advanced standards tailored to its own needs. This will support the sustainable growth of the aluminum industry in China. Water Cooling,Crown Water Cooling System,Tubed Type Water Cooling,High Power Water Cooling Crown Electronics CO., LTD , https://www.crownhaero.com