Aluminum Coatings for Hardware

[blondjohn]

Hi All,

I need advice. I want to refinish my cast aluminum deck cleats and extruded aluminum tracks for the headsail sheet cars. I thought I would go with a MIL-A-8625 Type II anodize, (that is a sulfuric acid bath process that gives a clear to dull grey coating depending on thickness applied) and specify a 1 mil coating thickness. One anodizer is telling me he thinks I need a coating of some type other than just anodizing on the aluminum. I'm considering having the parts anodized and then taking them to a powder coater and having a clear powder coat put on over the anodizing.

Has anyone done this? Has anyone been down this path of refinishing used aluminum hardware that can share advice and experience? I want an attractive aluminum appearance but with durability for the marine environment.

Thanks,

[DouglasPohl]

More information is needed. What will the aluminum be mounted to? What will insulate it from the base mount? etc... You need to consider the galvanic potential of aluminum for your selected device purpose.

Aluminum requires protection when mounted - done improperly its a real problem. Since aluminum has a more negative electro-chemical activity (voltage) than say steel - the aluminum then becomes an anode and wastes - used correctly this cathodic protection will protect the steel (i.e. hull) from electroysis so by changing the anodes (zinc anodes too) you can protect your investment in a steel hull. Google marine anodes.

Be sure to also consider this - how are you going to maintain the aluminum once it starts to show signs of deterioration? Painting aluminum is esthetic - beauty - since it will naturally oxidize and form a protective surface layer - SURFACE layer of protection. If mounted incorrectly, the base will deteriorate and soon the whole aluminum device will fail. Paint, powder coating, etc will look "pretty" but you will need be prepared with supplies for servicing - I doubt your sail sheet cars will roll-slide smoothly on coated surfaces... might want to consider marine stainless for better service. Marine stainless ALSO requires proper installation to prevent common corrosion - its all about electro-chemistry. Anodizing will look nice when you install it but a year later will be corroded. Stick with base metals that naturally offer the best protection for their intended service. YMMV

Smooth seas!