Sanding is not required between coats of TotalBoat Gleam Marine Spar Varnish if it is overcoated within 48 hours.

However, when transitioning to satin, it is best to allow the varnish to cure for 48 hours and lightly sand with 320-grit sandpaper in the direction of the grain, or use a dual action sander. Then clean away any sanding residue and apply Gleam Satin as directed.