Answer
For boat bottom paint prep, use 80 or 120 for heavy coating scuffing, then 180 or 220 for smoother primer prep.
Why it happens
Old marine coating needs cleaning and sanding that matches the next paint system.
Recommended grit
Use 80 or 120 for heavy old coating prep, then 180 or 220 for smoother primer prep.
Wet or dry
Dry with dust control unless the coating system requires wet sanding.
Success check
The old coating is clean, dull, and ready for the next coating step.
What to do
- Clean marine growth and residue first.
- Sand heavy old coating with 80 or 120.
- Refine with 180 or 220 if primer prep requires it.
- Remove all dust before recoating.
Avoid: Do not sand unknown marine coatings without proper protection.