Answer
For aluminum oxidation, start with 320 or 400, then refine with 600, 800, and 1000.
Why it happens
Oxidation needs a grit that cuts the dull surface layer before finer grits refine the marks.
Recommended grit
Use 320 or 400 for oxidation, then 600, 800, and 1000 for finer prep.
Wet or dry
Dry for initial oxidation removal; wet for finer stages.
Success check
The dull oxidation is removed and the scratch pattern is even.
What to do
- Clean the aluminum first.
- Sand oxidation with 320 or 400.
- Refine with 600, then 800 or 1000.
- Clean residue before finishing or polishing.
Avoid: Do not jump from oxidation removal directly to polishing.