Answer
For aluminum, use 180 or 220 for prep, then 320, 400, and 600 for finer smoothing.
Why it happens
Aluminum can show scratches clearly and should be refined gradually.
Recommended grit
Use 180 or 220 for prep, then 320, 400, and 600 for finer smoothing.
Wet or dry
Dry for prep; wet can help at finer stages.
Success check
The aluminum has an even scratch pattern without deep lines.
What to do
- Clean the aluminum surface.
- Start with 180 or 220 if scratches or oxidation need removal.
- Move through 320 and 400.
- Use 600 for finer prep.
Avoid: Do not leave metal dust or debris between grits.