Comparing Fluoropolymer Coatings Powder and liquid options for protecting aluminum By Henry L. Lowman n Canada and the United States, architects have traditionally specified liquid fluoropolymer coating products for aluminum architectural components because of the custom colour and small batching capabilities. This preference has prevented similar powder products from gaining significant market share in North America. However, that may soon change. A new generation of powder fluoropolymer is emerging, combining colour and small batching benefits of liquid coatings with the volatile organic compound (VOC)-free application of conventional powder coatings. This article outlines colour, and environmental and performance attributes architects should consider when specifying liquid or newer powder coatings for building projects. Comparing colour Colour restrictions—caused by manufacturing limitations—have been a drawback for conventional powder coatings. These products are made by melting together certain raw materials (i.e. resins, I pigments, and additives), then cooling and extruding the mixture into chips. The chips are ground into a fine finish powder coating and sprayed onto a metal substrate. Until complete, it is impossible for the powder coatings manufacturer to know the exact colour of the coating. If a specifying architect determines the look is wrong or does not meet its intended match, the process is repeated—often several times—until the desired hue is achieved. Next-generation powder coatings overcome these limitations. They permit more effective colour control and allow manufacturers to dramatically cut waste, lower costs, and generate small batches of custom colours more quickly. Despite this advance, liquid coatings retain one major advantage over powder coatings—the ability to achieve bright metallic finishes. While next-generation powders can be formulated with mica to produce a pearlescent effect, they are not yet available with the brightest aluminum flake. Metallic coatings with aluminum flake need a particular clear coat not currently compatible with 60 January 2010 Construction Canada CC_JanFeb10.indd 60 12/22/09 11:56:44 AM Photo courtesy Douglas Cardinal Architect Feature