Aluminum pretreatment: Old issues and new developments, part I
Pretreatment, regardless of whether the substrate contains ferrous or nonferrous metals, is of critical concern to today's powder coaters. Coating performance and customer expectations for quality and durability increase each year. The proper surface preparation of metal substrates has a wide window for failure because of numerous factors. This is the first of a two-part article that will explain why you may see numerous coating failures on nonferrous metals and what options you have to correctly pretreat aluminum and its alloys. The article will also provide examples of coaters who are producing consistent quality because of their pretreatment and control of the process.
The Aluminum Association1 compiles a number of interesting facts. For example, did you know that the US primary aluminum production average for the second quarter of 2003 was 7,413 metric tons per day, a 7.8 percent increase from the same quarter in 2002? Or that the average automobile manufactured today includes 257 pounds of aluminum. Determining the exact amount of parts, lineal feet, or castings that are coated each year in the US may be difficult, but if you look around, you'll notice a multitude of powder coated or painted parts every day, including aluminum castings for barbecue grills, railings, fences and shutters, entry gates, telephone and other communications devices, electrical enclosures, outdoor furniture, roofing systems, windows, architectural components, marine products, and numerous construction and consumer goods. Ask most custom coaters and they'll tell you that the percentage of nonferrous products being processed through their finishing line grows every year.