How to Sand Metal Rust Spots Before Painting (80–320 Grit Guide)

Rust is one of the biggest enemies of metal surfaces, whether on cars, tools, or outdoor furniture. To stop corrosion from spreading and ensure paint lasts, proper sanding is the most effective first step.

Why Sanding Rusted Metal Matters

Sanding removes flaky rust, smooths out pitted areas, and creates a profile that allows primer to bond securely. Painting over rust without sanding usually leads to peeling and recurring corrosion.

Best Sandpaper Grits for Rust Removal

• 80 grit: Heavy rust removal and paint stripping.
• 120 grit: Smoothing rough spots after coarse sanding.
• 220 grit: General surface prep before primer.
• 320 grit: Final smoothing before topcoats.

Tools You’ll Need

• Sandpaper sheets (80–320 grit).
• Wire brush or grinder for thick rust patches.
• Sanding block or orbital sander.
• Rust-inhibiting primer and paint.

Step-by-Step: Sanding Rust Spots

1. Clean the surface. Remove grease and dirt with a degreaser.
2. Strip heavy rust with 80 grit. Start with 80 grit (50-pack) for aggressive removal.
3. Smooth with 120 grit. Switch to 120 grit (25-pack) for evening out rough areas.
4. Refine with 220 grit. Use 220 grit (100-pack) to prepare for primer.
5. Finish with 320 grit. Apply 320 grit (25-pack) for final smoothing before painting.
6. Prime & paint. Use rust-inhibiting primer followed by your chosen topcoat.

Special Cases

Deeply pitted rust may require a wire wheel before sanding. For aluminum, avoid very coarse grits—start at 120 grit to prevent gouging the softer metal.

Pro Tips

• Always wear gloves and a dust mask when sanding rust.
• Feather sand the edges of paint into bare metal for smooth transitions.
• Apply primer immediately after sanding to prevent flash rust.

Aftercare

• Inspect surfaces regularly for new rust spots.
• Keep painted metal dry when possible to extend finish life.
• Reapply protective coatings every few years for outdoor items.

FAQs

• Can I paint directly over rust? No—remove as much rust as possible first.
• Do I need to sand after primer? A light sanding with 320 grit improves adhesion for the topcoat.
• What’s the fastest way to remove rust? Start with a wire wheel, then finish with sandpaper.

Watch & Learn

Stop rust in its tracks: Get 80–320 grit sandpaper sheets in 25, 50, and 100 pack options. Shop metal sanding sandpaper.