Tips for painting raw metal bumpers

Eastwood products work very well with what you are doing....

I like the Eastwood 2k epoxy primer spray cans for stuff like this. My home made trailer hitch mount I made to attach to the frame of my yamaha quad doesn't have a speck of rust or missing paint after 5 years parked outside.
 
I followed @Jerry Bransford advise on painting. Worked really well in my opinion. Check out my slides, I feel the paint
held up pretty good considering it was on it's side.

PXL_20221124_214924425.TS_exported_8667_1669748506978.jpg
 
  • Like
Reactions: Jerry Bransford
Here's what I would do...

1) Wipe down metal with acetone or aqueous degreaser (avoid alcohol, as most contaminants you're likely to encounter are going to be polar, for which acetone is more appropriate)
2) Scuff with green or red Scotch Brite pad, wiping with a fresh cloth as you go
3) Before the metal flash rusts, coat with at least one coat of self-etching primer... self-etching will help cut through any flash rust that develops (even the stuff you can't see)
4) OPTIONAL: coat with any automotive grade primer if you want a smoother finish or want to increase corrosion protection. Self-etching primer, as the name suggests, does indeed "etch" the surface; it's great for adhesion but poor for corrosion protection as it typically doesn't have the same levels of zinc as a non-etching primer.
5) Coat with paint of choice - I like VHT Epoxy for stuff like this (https://www.vhtpaint.com/specialty/vht-epoxy-all-weather-paint)
6) Regardless of whatever paint you use, coat within specific recoat time frame.