How to Sand Metal Car Parts Before Primer & Paint (80, 150, 220, 320 Grit Guide)

Automotive metal parts like fenders, hoods, and panels require careful sanding before applying primer and paint. Skipping proper sanding leads to peeling, uneven adhesion, and visible scratches. This guide explains the right grit progression to prepare car parts for a flawless paint job.

Why Sanding Car Parts Is Essential

Metal car surfaces often contain rust, scratches, or factory coatings. Sanding smooths imperfections, removes corrosion, and creates a consistent surface profile for primer and paint to bond securely.

Tools & Materials

• Orbital sander and sanding block
• Wire brush or grinder for heavy rust
• Degreaser and microfiber cloths
• Rust-inhibiting primer
• Masking tape and drop cloths

Best Grit Sequence for Automotive Metal

• 80 grit: Aggressive rust removal and paint stripping.
• 150 grit: Smoothing welds, filler, and scratches after coarse sanding.
• 220 grit: Prepping surface for primer adhesion.
• 320 grit: Final sanding for silky surface before primer or paint.

Step-by-Step: Sanding Car Metal Parts

1. Clean the surface. Wash and degrease panels to remove oil and dirt.
2. Strip rust and paint. Use 80 grit (50-pack) for heavy corrosion and thick coatings.
3. Smooth repairs. Switch to 150 grit (50-pack) to refine body filler and welds.
4. Prep for primer. Sand with 220 grit (100-pack) to create a consistent bonding surface.
5. Final sanding. Finish with 320 grit (25-pack) before primer or paint.
6. Clean again. Wipe with tack cloth to remove sanding residue.

Special Cases

• Deep rust pits: Fill with body filler after coarse sanding, then refine with 150 grit.
• New replacement panels: Lightly sand with 220–320 grit before priming.
• Aluminum panels: Avoid 80 grit—start at 150 to prevent deep scratches.

Pro Tips

• Sand in long strokes along the body lines for uniform appearance.
• Always degrease after sanding to remove contaminants.
• Wet sand at 320 grit to minimize scratches before primer.
• Use light pressure—let sandpaper do the work.

Aftercare

• Apply rust-inhibiting primer immediately after sanding.
• Store prepared panels in a dry area until painting.
• Recheck for scratches under bright light before painting.

FAQs

• Do I need to sand bare metal to a shine? No, primer bonds better to a slightly rough profile (220 grit).
• Can I paint over rust? Never—remove all rust first or it will spread under paint.
• Is 320 grit enough for primer? Yes, it’s the ideal finishing grit for primer adhesion.

Watch & Learn

Proper sanding ensures professional paint jobs that last. Stock up on 80 to 320 grit sandpaper sheets in bulk packs for automotive metal prep. Browse the full metal sanding collection today.