Q: Painting HRS

I've painted quite a bit of hot rolled mild steel with scale still on it. It is better to remove it, but if it's tight and even just prime it and paint it. If you do decide to remove it, I suggest soaking the parts in (diluted) muriatic acid, followed by a baking soda rinse, followed by a hot water rinse, followed by baking at 300°F for an hour if brittleness could even conceivably be an issue. Then immediately prime (while still warm to the touch if possible) and let the primer dry and check over the coat for coverage, and recoat if necessary, then your topcoat. Another good idea is hot-dip galvanizing. Around here there's a $75US minimum, which will galvanize about 200 pounds of steel, but it sure does a great job of long-term rust protection. It is possible to use an etching primer to paint over galvanizing, which may make that the best possible solution.

But for bumper brackets? Paint it, forget it. :-)

GWE