When you apply an alkyd oil-based paint over zinc plated or galvanized surfaces, a chemical reaction occurs between the two materials. This process, known as saponification, causes a build-up between the zinc surface and the coating. Over time, this can cause the coating to release from the surface. It is possible to paint galvanized surfaces with an oil-based system, however a water-based system will need to be applied as an intermediary coat. Our Zinsser Bullseye 123 brush-on primer is an excellent choice.
https://www.rustoleum.com/product-catalog/consumer-brands/zinsser/primer-sealers/bulls-eye-1-2-3-water-base-primer
If an aerosol is required, only our Stops Rust® Universal Bonding Primer is suitable for galvanized metal.
https://www.rustoleum.com/en/product-catalog/consumer-brands/stops-rust/universal-bonding-primer
The primer will act as a barrier coat and prevent the reaction from occurring.