How to Sand Metal Car Panels for Painting Without Burn-Through (180–600 Grit Guide)

Prepping car panels for paint is a critical step in auto bodywork. Sanding not only removes imperfections but also creates the ideal surface for primer and topcoat adhesion. This guide covers the best grit sequence for sanding metal car panels without risking burn-through or uneven surfaces.

Why Grit Sequence Matters in Auto Painting

Automotive finishes require precision. Starting with a grit that's too coarse can leave deep scratches visible under paint, while using too fine a grit too soon can reduce primer grip. The right progression ensures a smooth, durable finish.

Tools & Materials

• Dual-action (DA) sander and sanding block
• Automotive-grade tack cloth
• 180 Grit (25-pack) for initial surface shaping
• 240 Grit (50-pack) for refining after coarse sanding
• 320 Grit (100-pack) for smoothing before primer
• 600 Grit (10-pack) for wet sanding before topcoat

Best Grit Sequence for Car Panels

• 180 grit — Removes old paint, rust, and high spots.
• 240 grit — Blends coarse sanding marks and evens surface.
• 320 grit — Creates a primer-ready profile.
• 600 grit — Wet sands for a smooth, paint-ready finish.

Step-by-Step: Sanding Auto Body Panels

1. Initial cleaning. Wash with degreaser to remove contaminants.
2. Start with 180 grit. Sand with a DA sander to remove rust and damaged paint, keeping pressure light.
3. Switch to 240 grit. Blend and smooth areas to remove visible deep scratches.
4. Move to 320 grit. Hand-sand edges and curves to prep for primer application.
5. Wet sand with 600 grit. Use light, circular strokes to achieve a flawless finish before topcoat.

Special Cases

For panels with body filler, extend the sanding sequence to include feather-edging with 400 grit before primer to prevent visible transition lines.

Pro Tips

• Keep sanding pads clean to prevent swirl marks.
• Feather the edges where bare metal meets old paint for a seamless look.
• Use wet sanding only after primer or with fine grits to avoid clogging.

Aftercare

• Always wipe panels with a tack cloth before painting.
• Inspect under bright light for any imperfections before applying topcoat.
• Store unused sandpaper in a dry, dust-free container.

FAQs

• Can I skip from 180 to 320 grit? Not recommended—240 grit ensures a smoother transition and prevents sanding lines from showing through paint.
• Should I wet sand all car panels? Only with finer grits (400–600) to achieve a show-quality finish.

Watch & Learn

By following this grit sequence, your car panels will be perfectly prepped for painting without burn-through risks. Stock up on 180 Grit (25-pack), 240 Grit (50-pack), 320 Grit (100-pack), and 600 Grit (10-pack) to complete your auto refinishing project with confidence.