Answer
For small spackle pinholes, use 220 to smooth and 320 to feather before paint.
Why it happens
Tiny repairs need fine sanding so the patch blends without hollowing the wall.
Recommended grit
Use 220 for smoothing and 320 for feathering the edges.
Wet or dry
Dry.
Success check
The patch edge cannot be felt with a fingertip.
What to do
- Let spackle dry fully.
- Smooth the patch with 220.
- Feather edges with 320.
- Remove dust before primer or paint.
Avoid: Do not oversand the center of a small patch.