I need to paint some Simpson hold downs that will be exposed on a deck I’m building. They are zinc plated. I went to a very good paint store, Dunn Edwards here in Los Angeles, and they offer two metal primers. One is a rust inhibitor primer, curiously water based. The other is for galvanized metal and I believe that is oil based. I’m not sure which would be the best choice. Forgive my ignorance but is zinc plated a close cousin to galvanized? Assuming I pick an appropriate primer, how do I prepare the metal? For instance, should I wash it down with alcohol to clean off any oil? Should I wash it with vinegar to etch it? How would I go about this to give the primer the best chance to adhere? Thanks in advance.
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Zinc plated is the big brother of galvanized -- same metal, thicker coating, slightly different process.
The traditional treatment is to wash it down with vinegar. Though with any metal you want to wash it first with a detergent to remove the machine oils (or let it weather for some months).
The zinc needs to be degreased, and etched.
I would use this primer, http://tools.sjdiscounttools.com/up0741
I recommend this seller as I have personally bought from them before, great service. Be aware that this primer is probably available at a automotive paint store also.
I hear that oil based primers can saponify on zinc and fail, so I would avoid directly priming zinc with oil base primer.
I would topcoat with a true epoxy paint, or polyurethane.
Something else that would be nice is powder coating. That would most likely be a shop job, and I expect it would be somewhat pricey, but it would last a long time.