Answer
For plastic storage bins, sand only for repair or paint prep. Use 320 or 400 lightly, then 600.
Why it happens
Many bins are soft plastic, so sanding is useful only for repair or paint prep.
Recommended grit
For paint prep, use 320 or 400 lightly, then 600 for smoother visible areas.
Wet or dry
Dry.
Success check
The plastic is lightly scuffed without gouges or white stress marks.
What to do
- Clean the plastic bin first.
- Sand only if repair or paint prep requires it.
- Scuff lightly with 320 or 400.
- Use 600 for smoother visible prep.
Avoid: Do not sand soft plastic aggressively.