Barry,

What follows are some thoughts on exterior anodized aluminum and maintenance of the material in a public art context. I apologize for them being a bit random:

Oxide forms immediately on an aluminum surface during fabrication in the factory. This oxide layer can be regarded as a protective shield. If aluminum is scratched, the surface will seal immediately in the presence of oxygen. Aluminum is one of the most amazing and, at the same time, under-rated metals.

One of the most preferable aluminum alloys for outdoor architecture and art is Alloy 5052. Not only is it very receptive to anodizing it is very resistant to many naturally occurring environmental substances. This may be an added benefit depending on the kind of particles blowing around in the Phoenix wind. Concerns are strong acids and strong bases.

That being said,  I’ll talk briefly about anodizing. Anodizing is a process that allows specialty dyes to saturate the tops layer of the aluminum’s surface. Unlike paint it is actually soaking into the metal and deposited within the metal. The deeper the dye reaches the better. It helps fill the voids in the aluminum’s molecular structure and helps prevent other molecules from filling them in instead. Something of note: a deeper dye penetration improves your chances that the color won’t be removed from the surface when scratched.

Removing an anodized dye can be done with an off-the-shelf degreaser called Greased Lighting. I mention this because should someone want to vandalize the artwork, there is an easily accessible spray to do it with. I tend to think of the worst case scenarios for a reason: preservation of our public art collection. Sandpaper can also be used to vandalize a soft surface like aluminum.  

I recommend fabricating spare parts. All public artwork will be vandalized or damaged at some point in the future. It’s just the nature of public art or anything in the built environment. In an ideal world it would be helpful to have spare parts in storage when that damage does occur. Saving the digital cut-files in a would be helpful for future repairs as well, for the same reason.   

Lastly, there is a nasty thing called galvanic corrosion. Long story short: you must have an adequate barrier between the aluminum and any metal with a dissimilar electrode potential, such as steel. Without this a barrier your aluminum will begin to decay and can self-destruct in a surprising short time. The entire project would then require an expensive and time-consuming overhaul.

I hope this information helps in some way. Aluminum is really beautiful and will look terrific in the Arizona sun. I’d love to see images when it’s finished.

Best,

Frank    

From: public_art_network@americansforthearts.simplelists.com [mailto:public_art_network@americansforthearts.simplelists.com] On Behalf Of Barry S Sparkman
Sent: Thursday, May 10, 2018 2:28 PM
To: public_art_network@americansforthearts.simplelists.com
Subject: Anodized Aluminum Question

Greetings PAN Listserv:

We are working with an artist on a bridge project in Arizona that includes anodized aluminum. We would appreciate hearing from anyone that has experience with anodized aluminum for outdoor projects in the Southwest. We are concerned about long term durability and maintenance. We would also appreciate suggestions for anodizing companies in the region that have experience with outdoor architectural elements or public art.

Thanks,

Barry Sparkman

Project Manager

Phoenix Office of Arts and Culture

200 W Washington St., 10th. floor

Phoenix, AZ 85003

Office 602-262-4637

Desk 602-495-0893

Cell 786-543-2207

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