I bought a used trailer with a homemade box on it. The walls are plywood, the roof is galvanized sheet metal. The galv. roof was bare for at least 5 years, so the metal had plenty of weathering to remove the oils that are on new galvanized metal. Last summer I painted the whole trailer with Rustoleum brand oil based paint made for metal. I brushed it on, and gave it two coats. The paint on the wooden sides has held up well, but over winter the paint almost completely came off the galvanized metal roof. It actually peeled off in large sheets. Apparently the contraction of the metal caused it to come loose.
Is there any way to paint galvanized metal?