Answer
Stop sanding exposed paper. Use 180 or 220 lightly on compound areas only, then seal damaged paper before paint.
Why it happens
The sanding was too aggressive or the grit was too coarse on exposed paper.
Recommended grit
Use 180 or 220 lightly for final smoothing.
Wet or dry
Dry.
Success check
The patch is smooth without expanding the fuzzy paper damage.
What to do
- Stop sanding the fuzzy paper area.
- Remove loose dust.
- Use 180 or 220 lightly on compound areas only.
- Seal or repair damaged paper before painting.
Avoid: Do not keep sanding exposed drywall paper.