Finish up with 320 grit. I use a hard rubber flexible sander to do the turtle decks at this point. You should have a nicely leveled surface at this point with no major surface defects. Now is the time to weight the plane. Mike gives a reference weight of 32 oz for the bare fuse (no canopy or chin) mine hit the scales at 31.75 oz. So I am in the ball park.

Your next step is to brush or spray on a coat of balsarite to seal the surface from the laminating resin. I use a 3/4 or 1" nylon craft brush. Just paint on a nice neat coat. It dries almost as fast as you can paint.

I let the balsarite sit overnight so it gets good and hard. Then just go over the airframe with 320 on the block to smooth out the fuzzies.