Not sure how it would perform in your area, but I use "Trailercoat" by Petitt.
It is a urethane paint for boat trailers that get immersed in water when
launching a boat. It forms a moisture proof?? barrier against rust on
galvanized steel. Two coats are recommended. It is available in most
marine/boat stores for about $18.00 a quart. It seems to adhere well to rusty
surfaces and provide a pretty good seal.
When I paint a tower section, I use a brush and a mitt to apply the paint. You
can apply the second coat in 2-4 hrs.
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