Answer
For rough dried latex paint, use 400 lightly. Use 320 first only for heavier texture.
Why it happens
Dust, roller texture, or sanding debris can leave raised roughness after the paint dries.
Recommended grit
Use 400 for light smoothing. Use 320 first only when the roughness is more noticeable.
Wet or dry
Dry.
Success check
The paint feels smooth and is ready for another coat.
What to do
- Let the latex paint dry fully.
- Sand lightly with 400.
- Use 320 first only for heavier roughness.
- Clean dust before recoating.
Avoid: Do not sand latex paint while it is soft or gummy.