Answer
For aluminum boat paint prep, use 320 or 400, then 600 for finer primer prep.
Why it happens
Aluminum needs clean oxidation removal and an even scuff pattern before primer or marine coating.
Recommended grit
Use 320 or 400 for oxidation and paint prep, then 600 for finer primer prep.
Wet or dry
Dry for initial prep; wet can be used at 600.
Success check
The aluminum is clean, dull, and evenly scuffed before primer.
What to do
- Wash and degrease the aluminum.
- Remove oxidation with 320 or 400.
- Refine with 600 where a finer primer prep is needed.
- Clean residue before primer or coating.
Avoid: Do not paint over oxidized or dusty aluminum.