Answer
Fold or cut the sheet into a small piece and use the same grit sequence as the surrounding surface.
Why it happens
Loose paper can wrinkle or round over edges if it is not folded or supported.
Recommended grit
Use the same grit as the surrounding step, folded cleanly or wrapped around a small flat edge.
Wet or dry
Dry for most corner sanding; wet only for fine finishing stages.
Success check
The corner is smooth and matches the surrounding scratch pattern.
What to do
- Cut or tear a manageable piece of sandpaper.
- Fold it into a firm edge or wrap it around a small block.
- Sand with light pressure into the corner.
- Match the same grit sequence used on the surrounding area.
Avoid: Do not dig the folded edge into one spot.