How to Sand Auto Body Panels Before Painting (180, 220, 320, 400 Grit Guide)

Properly sanding auto body panels is essential before applying primer and paint. This step ensures adhesion, smoothness, and a flawless finish. With the right grit sequence, you can remove old coatings, feather edges, and prepare the surface for professional-quality results. This guide explains how to sand body panels step by step using 180, 220, 320, and 400 grit sandpaper.

Why Sanding Auto Body Panels Matters

Car panels often have scratches, chips, or layers of old paint. Sanding removes imperfections and creates the correct surface profile for primer. Skipping sanding risks paint adhesion issues and visible flaws in the final finish.

Tools You’ll Need

• 180–400 grit sandpaper – coarse through fine for proper progression.
• Sanding block or dual-action sander – ensures even sanding.
• Guide coat spray – highlights low spots while sanding.
• Water spray bottle – for wet sanding finer grits.
• Primer & automotive paint – applied after sanding.

Best Grit Sequence for Body Panels

• 180 grit: Removes old paint and rough imperfections.
• 220 grit: Smooths edges and feathers repair areas.
• 320 grit: Prepares surface for primer.
• 400 grit: Final sanding before applying paint or basecoat.

Step-by-Step Body Panel Sanding

1. Start with 180 grit. Strip old paint and rust using 180 grit (25-pack).
2. Move to 220 grit. Feather repair areas with 220 grit (100-pack).
3. Refine with 320 grit. Prep for primer using 320 grit (25-pack).
4. Finish with 400 grit. Wet sand lightly for a smooth, paint-ready surface using 400 grit (100-pack).
5. Clean thoroughly. Remove sanding dust with tack cloth before priming.

Special Cases

For bare metal, apply primer immediately after sanding to prevent flash rust. For plastic bumpers, avoid sanding below 220 grit to prevent gouging. Metallic finishes benefit from sanding up to 600 grit before basecoat for smooth reflection.

Pro Tips

• Always sand in overlapping passes for uniform results.
• Use a guide coat to identify low or uneven areas.
• Replace sheets frequently—auto paint clogs sandpaper fast.
• Wet sand finer grits to prevent scratches.

Aftercare

• Prime panels immediately to seal surfaces.
• Inspect under bright light before painting.
• Store sandpaper flat and dry for best performance.

FAQs

• Can I paint directly over 220 grit sanding? Not recommended—always refine up to 320–400 grit.
• Do I need to sand new car panels? Yes—light scuffing ensures paint adhesion.
• Is wet sanding necessary? For 400 grit and above, yes—it prevents scratches and improves smoothness.

Watch & Learn

For reliable auto refinishing, explore our metal sanding collection.