Answer
For copper oxidation, start with 600, then refine with 800, 1000, and 1500 before polishing.
Why it happens
Oxidation needs removal with a grit that cuts the surface layer before polishing.
Recommended grit
Use 600 for light oxidation, then 800, 1000, and 1500 before polishing.
Wet or dry
Wet for finer stages.
Success check
The oxidation is reduced and the scratch pattern is even.
What to do
- Clean the copper first.
- Use 600 grit for light oxidation.
- Refine with 800, 1000, and 1500.
- Polish or protect the copper after sanding.
Avoid: Do not start too coarse on decorative copper.