Q. Do you know of any testing that has been done to compare powder coating to outdoor exposure specifications? I know a few liquid coatings that have been tested, but I don’t know that much about powder performance in outdoor applications—A.J.
A. Outdoor testing of powder coating materials is common. In some cases, a particular powder coating may be compared with other powder materials and/or with a liquid coating. Manufacturers of coatings do this kind of testing routinely. I am not aware of any exhaustive testing data that is available that will show some universal comparison. The most common outdoor specification in the U.S. is that of the AAMA (American Aluminum Manufacturers Association).
A single coat of a typical powder polyester formula will meet or exceed the one-year weathering requirement as described in AAMA 2603. This is roughly equivalent to a layer of liquid primer coat and two-component liquid polyester or a single-component acrylic. A single coat of super-durable powder polyester will meet the five-year weathering requirement described in AAMA 2604. This is roughly equivalent to the performance of a primer coat and high-quality two-component liquid polyester coating. A powder formulated with a fluoropolymer is roughly equivalent to a liquid primer and Kynar topcoat and will meet the 10-year weathering requirement described in AAMA 2605.
You may be able to get specific weathering data from the coating manufacturers. Better still, if you know what you want the coating to do, tell you powder supplier to give you the right product. Powders are available that can compare to any outdoor liquid coating as long as you are clear on what you require.
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