Auto Body Sanding Before Paint: Grit Sequence for Professional Results

When repainting a car panel, bumper, or full vehicle, surface prep is everything. Auto body sanding ensures that old paint, primer, and imperfections are leveled before the color coat is applied. This guide breaks down the grit sequence and best practices for sanding automotive surfaces like a pro.

Why Sand Before Painting a Car?

Sanding removes old clear coat, flaking paint, and surface scratches while giving primer and paint something to grip. Skipping this step can lead to peeling, poor adhesion, and an uneven finish.

Tools You’ll Need

• Wet/dry sandpaper sheets
• Sanding block or orbital sander
• Masking tape and plastic sheeting
• Primer and body filler (if needed)
• Tack cloth and microfiber rags

Best Grit Sequence for Auto Body Prep

• 80 grit: Heavy paint removal and shaping body filler.
• 180 grit: Levels filler and blends edges.
• 320 grit: Smooths primer for topcoat adhesion.
• 600 grit: Final wet sanding before paint application.

Step-by-Step: Sanding an Auto Body Panel

1. Strip damaged areas. Use 80 grit (25-pack) to remove peeling paint and shape filler.
2. Blend filler edges. Switch to 180 grit (100-pack) for smooth transitions.
3. Prep for primer. Use 320 grit (50-pack) to create a uniform surface.
4. Final wet sanding. Finish with 600 grit (25-pack) for a silky texture ready for paint.
5. Clean thoroughly. Wipe with tack cloth and degreaser before spraying primer and base coat.

Special Cases

For deep scratches, apply body filler before sanding. For blending new paint into old, feather edges carefully with 600 grit to avoid visible lines.

Pro Tips

• Always sand in a crosshatch pattern to avoid visible grooves.
• Wet sand finer grits (320 and 600) for a smoother finish and less dust.
• Use long sanding blocks on flat panels to prevent waves.

Aftercare

• Seal bare metal with primer immediately after sanding.
• Store sandpaper sheets flat to keep them in good condition.
• Inspect panels under bright light before painting.

FAQs

• Can I skip 180 grit and go straight from 80 to 320? It’s not recommended—180 grit ensures smoother filler blending.
• Is 600 grit always required? For glossy finishes, yes. For primer-only prep, you can stop at 320 grit.
• Do I need to sand the entire car? Only sand areas being painted, but feather surrounding edges for blending.

Watch & Learn

With the right grit sequence, auto body sanding sets the stage for a paint job that looks factory fresh. Stock up on 80 to 600 grit wet/dry sandpaper sheets for your next automotive project.