ASTM D7869 or SAE J2527 – Which is More Appropriate?

Over ten years ago, ASTM D7869 “Xenon Arc Exposure Test with Enhanced Light and Water Exposure for Transportation Coatings” was first introduced as a new and revolutionary weathering standard for automotive and general transportation coatings. This standard is based on the careful consideration of photochemical- and moisture-related coating degradation and a hot, humid end-use environment.

The development and publication of this new standard by international companies was spearheaded by Ford and included Atlas, BASF, Boeing, Q-Lab, and Bayer Material Science. The goal of the new method was to simulate the degradation of transportation coatings as realistically as possible and to offer a better weathering protocol than the well-established SAE J2527 “Performance Based Standard for Accelerated Exposure of Automotive Exterior Materials Using a Controlled Irradiance Xenon-Arc Apparatus”.

As of this publication, published data on the use of ASTM D7869 remains limited with no clear indication as to whether ASTM D7869 or SAE J2527 is more appropriate for a broader range of materials. Therefore, when considering if ASTM D7869 or SAE J2527 might be more appropriate for an alternative material or application, the following summary compares both test methods by relevant categories. While both standards were developed for automotive coatings, they may be applicable to other applications and materials like moisture sensitive polymers such as polyesters and polyamides.

A new Atlas publication compares the test parameters of both methods regarding:

The answer is clear: it depends! The appropriate test method always depends on the test material and its specific failure modes in the target end use environment. Plastics, powder coatings, window profiles, and other materials have different failure modes and might require different test approaches. Both SAE J2527 and ASTM D7869 are related to hot and humid environments. Other end-use environments might cause different material failures. This should also be considered in the selection of the appropriate test method.

ASTM D7869, while maybe not perfect, is an example of high-level standard development for a specific application and end-use environment. More standard development approaches for other materials such as plastics or other types of coatings should follow this direction in the future. For the detailed comparison between SAE J2527 and ASTM D7869 see the brand-new Atlas standards publication.

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