Debate: Should you use filler primer on bare metal or skip it?

My old shop foreman swore by skipping primer on small dents and going straight to paint, said it bonds better. But my new guy at Carter's Landscaping convinced me to try filler primer after a rust spot came back on a '99 F-150 I did 6 months ago. Who else has had a primer job bite them either way?

2 comments

2 Comments

sullivan.spencer8d ago

Has anybody tested how different temps or humidity levels mess with that drying time thing? I swear half the primer failures I've seen trace back to someone spraying it on a damp morning and acting surprised later.

bennett.vera9d ago

My '92 F-250 taught me this the hard way back in '04. I did a rust repair on the rocker panel, sanded it down to bare metal, and skipped the primer because my old man said it was a waste of time. Six months later, that spot looked like someone had thrown a handful of rust flakes at it. I had to grind it all back down and start over with a filler primer from the hardware store. That stuff has never let me down since, but I've heard some guys say it can trap moisture if you don't let it dry fully before the top coat. Maybe that's where the whole "primer or no primer" debate really lives - in the prep work and drying time more than the product itself.