Answer
Cork should only be sanded lightly. Use 320 or 400 and avoid heavy pressure.
Why it happens
Cork is soft and porous, so coarse grits and heavy pressure remove material unevenly.
Recommended grit
Use 320 or 400 only for very light smoothing. Avoid coarse grits.
Wet or dry
Dry.
Success check
The cork remains flat and intact with no torn edges.
What to do
- Test on a hidden area first.
- Use 320 or 400 with very light pressure.
- Sand only raised spots or rough edges.
- Clean loose dust gently.
Avoid: Do not sand cork with coarse grit or heavy pressure.