what paint to go over cold galvenized on a triler

Talk to an experienced clerk in a paint store. Automotive spray paint didn't stay on cold galvanizing very well for me.

IIRC Rustoleum do a bright cold galvanising paint as well as dull versions so maybe try some of the bright paint over what you have applied. I've used it myself and while not a perfect match for hot dip the bright cold galvanise paint looks much better than the dull stuff.

And you can topcoat the cold galvanize paint with regular rustoleum (or just about any other enamel or acrylic) paint.

"Cold galvanizing" refers to several different materials. The common one, from Rust-Oleum and others, is a reggular organic paint binder with up to 95% zinc powder. It's the least protective because it generally hresults in poor electrical contact among the zinc particles. It's often recommended to top-coat it and I'd just check with the company that made it for recommendations on preparing it for a top coat.

Another material, one that I haven't seen for about ten years but which was popular for a while for coating boat trailers, is two-part epoxy paint with the same zinc powder. Top-coating epoxy is always tricky. It develops an "amine blush" on the surface from the amine curing agent. You can't sand it off; it just smears around. Acetone won't help, nor will other paint thinners.

However, thankfully it's water soluble and the blush can easily be washed off with soap or detergent and water. My favorite is TSP, for the same reason that it's used for prepping walls for painting: it doesn't leave a residue.

The third material is harder to get in ordinary consumer products but it's the best, and you'll find it from commercial sources. It's INORGANIC binder (usually ethyl silicate) with 90 - 95% zinc powder. The reason it's best is that it has good electrical conductivity with the surface and with the particles themselves. That's essential to get a true "galvanizing" effect, which is a sacrificial electrolytic phenomenon in which the zinc is the sacrificial anode.

If you happened to get that, you'd better check with the supplier about coating it. It's the one that least needs top coating.

Whatever you use, keep stirring or shaking the hell out of it as you use it, or you'll get wildly different percentages of zinc as you spray, roll or brush.

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