Does anyone have any suggestions about painting galvanized metal? I have built a post and beam type structure (a car port actually) and the posts are on “U” shaped Simpson post brackets coming out of the concrete piers. These are galvanized but the bolts, nuts and washers are (I assume) mild steel (and are beginning already to show some rust.) I’ve heard that rubbing galvanized metal vigorously with vinegar just before priming and then painting is the  way to go. I’ve also heard that an oil based primer/paint combination is best. Another source has recommended Epoxy Kote but the info I’ve been able to get about that makes no mention of what special things need to be considered for galvanized metal.

I’ve also got another situation that bears on this: a large (28,000 Gal) galvanized metal water tank  that was spray painted several years ago with primer and then with paint: the walls are still holding up well but the paint on top is flaking off very badly. I assumed it was because of UV degradation but someone suggested that the walls are kept cool by the water while the roof isn’t and it’s the diurnal heating and cooling cycles that have done in the roof paint. The answer to my first problem would probably apply to repainting the tank as well but on a much larger scale ofcourse.

And finally, what is the best way to preserve mild steel from a coastal (salt spray) environment? Before you suggest pouder coating, perhaps I should restrict the suggestions to something I can buy and apply on location.