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Prepping metal for billboards in the jungles of Africa

December 1, 2010

I volunteer at a primate orphanage in Africa, in the tropical rain forest. As one of my tasks, I hand paint signs and billboards for the organization. Resources are limited and conditions challenging. Can you help advise me on prepping metal surfaces for the best chance of the signs lasting, not rusting, and paint adhering? I need help with both the steps and materials. Would sure appreciate it!

Here is what I'm working with:
Metals: sheet steel, aluminum, galvanized aluminum
Paint: lead-based gloss enamel
Anti-rust coating: available
Primer: not available
Sandpaper, 400 grit available (and I'm bringing 1200 with me)
Steel wool (coarse): available
Kerosene, gasoline, turpentine ⇦this on eBay or Amazon [affil links] : available (I was using this to clean the surface after I sanded the rust off, instead of water).
Other specialty products: probably not available. Possibly could get some tools.
Water: by bucket only (no electricity, no running water).
Climate: hot (80s, 90s), very humid, often rainy, often sunny. I paint outdoors, can protect from the rain and sometimes from sun.
I return to Africa January 1 and would appreciate any help prior to that.

Robin Huffman
Corporate interior designer, artist, volunteer - Keizer, Oregon, USA

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Greetings Robin,

I just found this forum on the web and I hope this reaches you in time.

Primer, although unavailable, is probably the best thing you can do to help the paint adhere and last for a long while in the harsh environment. With the lead paint, I am sure you have found it to "powder" and peel away.

Aside from that, with the aluminum sheets you have at your disposal, I would try doing a vinegar ⇦in bulk on eBay or Amazon [affil links] wash with steel wool to help rough up the surface to get the paint to adhere. The acid in the vinegar will help to pit the aluminum and make scoring easier with the steel wool so the paint, without primer, will stick. vinegar, I hope, is easy to source where you will be doing your work. I'd also try dividing up one sign board into sections and seeing what works best, then going from there for this season you are working.

Good luck!

J.D. Prowse
Gadfly, Renaissance Man, Historic Home Owner - Everett, Washington, U.S.A.
December 30, 2010