Q. We have been using liquid paint for our architectural aluminum extrusions for about 20 years, but have considered using powder coatings to reduce our VOC and save cost. We have seen some successful projects with powder, but we also hear stories about the UV resistance of powder when compared to high-performance liquid coatings and other performance issues. Can powder coatings meet AAMA 2604 and 2605 standards? What are the strengths and limitations of powder versus liquid coating? B.A.
A. There are two critical qualifiers that are important to the discussion. First, the surface has to have the right treatment to ensure good adhesion and corrosion resistance. For architectural aluminum, this means using chrome, chromate, or a high-quality, non-chrome conversion coating. Second, the coating must be a high-quality material with the necessary properties to meet the specification. If the surface treatment is good and the coating is a superior coating with the needed properties, liquid and powder can both be effective.
The AAMA standards describe treatments in some detail and recommend minimum performance levels and rigorous testing to meet the specification. These specifications include minimum coating weights for the chrome and severe adhesion testing to confirm success.
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