Answer
Let the coat cure, then sand dust nibs lightly with 400 or 600 and clean before the next coat.
Why it happens
Dust settled into the coating or remained after sanding.
Recommended grit
Use 400 or 600 lightly between coats where the coating instructions allow.
Wet or dry
Dry or wet depending on coating instructions.
Success check
The surface feels smooth before the next coat.
What to do
- Let the coat cure as directed.
- Sand the nibs lightly with 400 or 600.
- Clean dust carefully.
- Apply the next coat on a clean surface.
Avoid: Do not sand wet or soft coating.