Auto & body
Stripping rust off a fender
Get to bare metal. Then keep going for thirty seconds.
Surface rust is a sandpaper job. Pitted rust needs more aggressive abrasive. The climb depends on how deep it went.
The climb
The exact sequence, in order.
- 1 40
Strip the rust off the surface
Belt sander or 4-1/2" angle grinder with sanding disc. Stop at bare metal.
Reach for
3M 9×11 40-Grit Sandpaper (5-pack)
- 2 80
Refine the bare metal
Random orbital with even pressure.
Reach for
Norton 3X Sheet Sandpaper — 80 Grit (20-pack)
- 3 180
Prep for primer
DA sander with a soft pad. Light passes.
Reach for
Mirka Gold 5-inch Hook & Loop Disc Assortment
Watch out for
The things that quietly ruin the job.
- ·Primer the bare metal within the hour. Rust starts re-forming the moment the air hits it.
- ·Pitted rust may need media blasting before sanding. If the pits are deeper than a credit card edge, sandpaper alone won't reach the bottom.
- ·Wear a respirator — old paint may contain lead, and rust dust is ferrous junk you don't want in your lungs.
Questions people ask
The practical part.
Chemical rust remover vs sandpaper?
Chemical (phosphoric acid) converts rust without removing it. Good for pitted areas; useless for smooth surface rust. Combine both for serious restoration.
What primer for bare metal?
Etching primer first. It bonds to bare metal in a way regular primer can't.
Keep going