Answer
Use 320, 400, or 600 between varnish coats, following the varnish instructions and sanding lightly.
Why it happens
Between-coat sanding should remove dust nibs and help the next coat lay smoother without cutting through.
Recommended grit
Use 320, 400, or 600 depending on varnish instructions.
Wet or dry
Dry unless the varnish instructions allow wet sanding.
Success check
The coat feels smooth and is not cut through.
What to do
- Let the varnish cure as directed.
- Sand lightly with 320, 400, or 600.
- Remove dust thoroughly.
- Apply the next coat on a clean surface.
Avoid: Do not sand uncured varnish.