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

Painting over metal without proper prep leads to peeling, chipping, and rust returning. The secret to a lasting, smooth finish is thorough sanding in the correct grit sequence—plus the right primer. This guide walks you through how to sand metal for painting, from rust removal to final surface prep.

Why Sand Metal Before Painting?

Sanding removes rust, flaking paint, and surface oxidation while creating a texture that primer can grip. Skipping this step means your new paint may fail prematurely.

Best Grits for Metal Prep

• 80 grit: Heavy rust removal and stripping old paint.
• 120 grit: Smoothing after rust removal.
• 220 grit: Final shaping before primer.
• 320–400 grit: Ultra-smooth finish for topcoats.

Step-by-Step: Sanding Metal for Painting

1. Clean the surface. Remove grease and dirt with a degreaser.
2. Remove heavy rust. Use 80 grit sandpaper or a wire wheel attachment for deep corrosion.
3. Smooth with 120 grit. Eliminate sharp edges and level the surface.
4. Refine with 220 grit. Create a consistent profile for primer adhesion.
5. Finish with 320–400 grit. For glossy paint jobs, this step ensures a mirror-like base.
6. Clean again. Wipe with solvent or tack cloth to remove dust.
7. Prime & paint. Use a rust-inhibiting primer, then apply your chosen topcoat.

Pro Tips

• Always wear a mask—metal dust is hazardous.
• Use wet/dry sandpaper for finer grits to reduce dust and clogging.
• For curved areas, wrap sandpaper around a foam pad for even pressure.

Common Mistakes

• Painting over rust—any remaining rust will continue to spread under paint.
• Skipping primer—metal needs primer for paint to stick.
• Using too fine a grit before primer—stopping at 220 grit gives the best adhesion.

FAQs

• Can I sand aluminum the same way? Yes, but avoid aggressive grits like 80 unless removing heavy oxidation.
• Do I need to wet sand metal? Only for the finest grits (320–400) before topcoat for a high-gloss finish.

Watch & Learn

Stock up on the right grits—80 grit through 400 grit wet/dry sheets available in packs of 10, 25, 50, and 100. Shop all sandpaper.

Shop matching sandpaper