How to Sand Metal Before Painting: Rust Removal & Smooth Finish (80–400 Grit Guide)

Painting over metal without proper preparation can lead to peeling, chipping, and rust coming back much sooner than expected. The secret to a long-lasting, smooth finish is sanding with the correct grit sequence and applying a quality primer. This guide will walk you through every step of the process so your paint job looks great and lasts for years.

Why Sand Metal Before Painting?

Sanding removes rust, failing paint, and surface oxidation while creating a texture that primer can grip. Without sanding, the new paint won’t adhere as well, leading to premature failure.

Best Grits for Metal Prep

• 25-sheets-grit-80" target="_blank" rel="noopener">Grit 80 (25-pack): Aggressive removal of rust and thick paint layers.
• 50-sheets-grit-120" target="_blank" rel="noopener">Grit 120 (50-pack): Smoothing and leveling after coarse sanding.
• Grit 220 (100-pack): Final shaping before primer for consistent adhesion.
• Grit 400 (25-pack): Ultra-smooth surface prep for glossy or high-finish coats.

Step-by-Step: Sanding Metal for Painting

1. Clean the surface. Use a degreaser or mild detergent to remove oils, dirt, and debris. Let dry fully before sanding.
2. Remove heavy rust. Start with Grit 80 to strip rust and loose paint quickly.
3. Smooth the surface. Switch to Grit 120 to remove scratches from the coarse pass.
4. Refine further. Use Grit 220 to create a uniform texture for primer adhesion.
5. Optional high-finish prep. For glossy paints, finish with Grit 400 for a silky-smooth base.
6. Clean again. Vacuum thoroughly, wipe with mineral spirits, and use a tack cloth to remove all dust before priming.

Pro Tips

• Always wear protective eyewear and a dust mask when sanding metal.
• Use wet/dry sandpaper for finer grits to reduce clogging and airborne dust.
• For contoured areas, wrap sandpaper around a foam pad for even pressure.

Common Mistakes

• Painting over rust—oxidation will continue under the paint.
• Skipping primer—paint alone won’t bond well to bare metal.
• Jumping from coarse to fine grit—this leaves visible scratches beneath the finish.

FAQs

• Can I sand aluminum the same way? Yes, but use lighter pressure and avoid overly coarse grits unless necessary.
• Do I need to wet sand metal? Only for the final fine grit before applying a high-gloss topcoat.

Watch & Learn

Need more grit sizes? Shop all sandpaper for every stage of your project.

Shop matching sandpaper