How they affect the coating process and component performance
In recent years, powder coatings have taken an increasing share of the market in North America for coating of metal building components, with an emphasis on aluminum components such as fenestration elements and decorative façades.
Why is powder coating becoming a leading choice? What do you need to know about the coating process and how does it affect performance of the components you will install?
In other parts of the world, especially in Europe, powder coatings have been used on aluminum building components for over 30 years. In the United States, liquid coatings systems, including coil coatings, and anodizing, continue to hold a majority share of the market, and are familiar to most architects. However, a growing understanding among architects and specifiers about the attributes of powder coatings are changing the market mix.
Process and Color
One important factor with powder coatings is that both in the process of producing the powder, and in its application, no liquid solvents are required. Therefore, powder coatings are essentially a volatile organic content (VOC) -free coatings system, increasing their desirability as builders and architects vie to produce increasingly green projects.
Secondly, the range of color and appearance capabilities in powder coatings has developed rapidly, allowing powder coatings to replace liquid coatings in almost all kinds of design work. While metallic coatings may continue to present some challenges, even these can be accomplished with powder coatings for most applications. With the use of sublimation processes, powder-coated components can now even be produced with wood grain and other special-effect appearances.
Further, many component suppliers have noted that powder-coated components have a more scratch- and chip-resistant surface than comparable liquid coatings. This means that these components fare better during and after shipment to job sites, with less issues of on-site damage requiring repair.
Various Formulations
Powder coatings are also available in various formulations, allowing applicators to provide systems that meet American Architectural Manufacturers Association (AAMA) 2603, 2604 and 2605 levels of performance. Many major powder coatings suppliers to the architectural market run certification programs to identify competent applicators, who in many cases are then provided with significant warranty programs on a job-by-job basis. Through an initial in-depth process audit, with follow-on checks at least annually, a certified applicator will have proven their ability to run an extremely consistent pretreatment and paint application process. This ensures the performance of the coatings system will actually meet all performance requirements.
A qualified applicator will be able to guarantee that its pre-treatment process is properly designed, and properly maintained, to meet all performance requirements. A multi-stage wash-and-preparation process is absolutely required in order to achieve the desired coatings system performance. Constant monitoring of the various pretreatment stages, and regular testing of coated components to verify proper cure, paint adhesion and other factors is an absolute requirement of any applicator certification program.
For the future, continued developments in lower curing temperatures for powder coatings have led to the feasibility of using powder coatings on building components made of alternate substrates such as fiberglass pultrusions and a range of plastics. These offer the potential to provide some alternative materials for use with metal buildings, with a range of possible benefits.
Tom Branscome is market manager, architectural coatings at Milwaukee-based Hentzen Coatings Inc. For more information, visit
www.hentzen.com
