[lupo]

Do not use black moisture cured urethane's. These coatings are concrete primer with black pigment. When God created permanent rust sealer's it only came in one color silver. The resin blocks the moisture, the aluminum flake in layers two coats blocks the oxygen. This is the most powerful of your industrial primers. Seal the roof with the permanent rust sealer and followed up with epoxy surfacer. I've been doing it this way for years with great results