How to Sand Plastic Car Bumpers for Paint (220, 320, 400, 600 Grit Guide)

Plastic car bumpers are designed to absorb impacts but their glossy surface makes painting difficult. Proper sanding ensures new paint adheres and lasts. This guide explains how to sand plastic bumpers safely using the correct grit sequence.

Why Sanding Bumpers Matters

Bumpers often come with a smooth finish or factory coating. Without sanding, paint will peel or chip quickly. Sanding scuffs the surface, evens out imperfections, and preps for primer.

Tools & Materials

• Wet/dry sandpaper sheets
• Sanding block or sponge
• Tack cloth and microfiber towels
• Plastic primer
• Respirator and gloves

Recommended Grit Sequence

• 220 grit: Initial scuffing of the glossy bumper surface.
• 320 grit: Refining scratches and smoothing filler.
• 400 grit: Prepping for primer and evening out the texture.
• 600 grit: Final wet sanding before applying paint.

Step-by-Step: Sanding Car Bumpers

1. Clean first. Wash bumper with degreaser to remove dirt, oils, and wax.
2. Start with 220 grit. Use 220 grit (100-pack) to scuff glossy areas for primer adhesion.
3. Smooth filler. Switch to 320 grit (25-pack) to refine scratches and smooth repaired areas.
4. Prep for primer. Sand with 400 grit (50-pack) for a consistent surface.
5. Final sanding. Finish with 600 grit (25-pack) wet to ensure paint bonds evenly.
6. Clean again. Wipe with tack cloth before applying primer.

Special Cases

• Unpainted bumpers: Always scuff with at least 220 grit before primer.
• Repaired areas: Feather edges with 320 grit for seamless blending.
• Minor scratches: Sand with 400–600 grit only if repainting isn’t needed.

Pro Tips

• Wet sand finer grits to prevent melting plastic.
• Sand in overlapping strokes for even coverage.
• Always apply plastic adhesion promoter before primer.
• Do not oversand edges—plastic is thinner there.

Aftercare

• Allow paint to fully cure before washing—typically 7 days.
• Wax bumpers only after 30 days to protect paint.
• Inspect and touch up chips quickly to prevent peeling.

FAQs

• Do I need to sand a new bumper? Yes, even new bumpers must be scuffed for primer to bond.
• What grit before primer? 400 grit creates the best surface for primer adhesion.
• Can I paint over scratches without sanding? No, sanding is required for a smooth finish.

Watch & Learn

Sanding bumpers the right way ensures long-lasting paint jobs. Stock up on 220 to 600 grit sandpaper sheets in different pack sizes. Explore the full fine sandpaper collection for automotive refinishing.