Despite advertising claims to the contrary, it is not a good idea to paint over rust. Some paints are recommended for slightly rusted metals, but better results can always be achieved with proper surface preparation. Paints do not penetrate rust scales, and loose rust may fall off, taking the paint with it. Use a vinyl primer, or finish with epoxy paint. Ordinary aluminum can be primed with zinc chromate primer.
Epoxy paints adhere well to deglossed stainless steel.
Remove the green patina from old copper with phosphoric acid. Wear rubber gloves and goggles when working with acids. A good brush, or a good roller, can be cleaned and used over and over again. The correct choice of scrapers, sandpaper and other prep tools is just as important, if not more important, than having the right brush or roller. Safety Exercise caution when working on ladders, and if you need access higher than your stepladder provides, be extra cautious.