Answer
For plastic paint prep, start with 400 for normal scuffing. Use 320 only for uneven spots, then finish with 600 before primer or paint.
Why it happens
Plastic needs enough scratch for adhesion, but coarse grit or heavy pressure can gouge and leave marks under paint.
Recommended grit
Use 400 for normal plastic prep, 320 only for rough spots, then refine with 600 before coating.
Wet or dry
Use dry sanding for simple scuffing. Use wet sanding with 600 grit when the plastic can safely be rinsed and needs finer prep.
Success check
The plastic is clean, evenly scuffed, and free of deep sanding scratches before coating.
What to do
- Clean the plastic to remove grease or residue.
- Start with 400 grit for normal paint prep.
- Use 320 only on rough or uneven spots that 400 does not level.
- Sand with light pressure to avoid heat buildup.
- Move to 600 grit for finer prep before coating.
- Wipe or rinse residue according to the paint system.
- Let the surface dry fully before primer or paint.
Avoid: Do not start with 120 or 180 on normal plastic prep. Those scratches can show through paint.