Ask the Expert: For fleet refinishing, does aluminum require any special treatment when painting?

Q: For fleet refinishing, does aluminum require any special treatment when painting?

Dan Szczepanik, Global Product Manager - Fleet & Manufacturing, Sherwin-Williams Automotive Finishes: Yes. First, know which grade of aluminum you are using (5052 is most common for truck parts). There are many grades made with different metals added to change the aluminums properties. Also, use a primer designed to be applied over aluminum by talking with your coating supplier. Some primers can go over multiple metals like cold rolled steel, aluminum and stainless steel, while other primers can only go over one type of metal. The last thing you should understand about aluminum is it does corrode. Unlike steel, which corrodes to a red iron oxide, aluminum corrodes to a clear aluminum oxide. This clear aluminum oxide then creates a barrier and prevents further corrosion. The problem is aluminum oxide can interfere with paint adhesion. It is best practice to paint aluminum no longer than four hours after cleaning and sanding. After four hours, there can be a greater amount of aluminum oxide on the surface and could cause adhesion issues. Work with your coating supplier to identify the best prep and primer for the aluminum you are using.

Information provided by: Sherwin-Williams Automotive Finishes