Clear E-coat vs. Anodizing

 Q. I am working on a project, and the customer is insisting on anodizing (10 µm thickness) an aluminum casting made from A413 cast aluminum. I don’t believe the surface finish will come out very good. I have told them that we can clear E-coat the part and get the same protection. The problem is that I can not find a specification for clear E-coating on aluminum castings to show them.
Can you help? G.T.

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A. For starters, I am going to assume your project does not have enough volume to justify its own E-coat line.
I suspect your customer is suggesting anodizing because they know it is a widely accepted and standard process for aluminum substrates. Also, a lot of good things have been done in recent years with anodizing processes. And, perhaps they feel it would be more likely that they can find a reasonably located source for anodizing.

E-coat lines with the capability to apply clear paint are very rare. When they do exist, they are usually captive within a manufacturing plant, and the pretreatment process is designed for the substrate to be coated for the products that plant makes. In addition, when applying a clear coating, pretreatment system selection is critical in order to maintain the visual integrity of the surface. So, there might not be a coater that can or would be capable or willing to do this within reasonable geographic range for logistical purposes.

However, if you still want to look for something like a specification, you might contact some of the suppliers of E-coat paints and ask them if they have a data sheet for one of their clear E-coat materials that might be appropriate for what you are trying to do. You can get information about E-coat paint suppliers on the Web site for The Electrocoat Association, www.electrocoat.org.