Sanding is nearly done

Five hours of sanding the 410 mix seems to have finished it off. It's amazing to see the nice glossy surface that you think is fair is actually fairly bumpy. The sander really knocks those bumps down and a consistent milkiness is the goal.

After the sanding, I still found some low spots, so I filled those.  

Sanding is done, low spots filled

Couple more low spots. filled.

One more sanding by hand to knock those down and she'll be ready for a coat or two of graphite epoxy.

Then I'll have a simple sanding job to get rid of the stipple on that. But since the underlying layer is smooth, that should go by fairly easy. The point is to sand the easy stuff, not the really hard stuff.

Warning. The 410 generates a lot of dust. Wear a respirator. I have a plastic tent with zipper doors set up in the garage, but the dust still escapes up over the top.
I rigged up a box fan with a furnace filter and that really cut down on the airborne dust.

box fan with furnace filter

I used a nice 5" random orbital sander for the flat areas (that I originally bought for my kayak build). The corners and sensitive areas were done either by hand or with a little mouse sander that I have. Usually by hand.
I heartily recommend Mirka Abranet fiberglass mesh sandpaper. Be sure to pick up a protective hook & loop barrier pad or the abranet will destroy the hooks on your sander.
And when you think the abranet is done or too clogged, take it off and roll it up so you can sand the fillet edges. I went through only about 4 sheets through the whole hull sanding.

L-to-R: respirator, rolled up abranet, abranet, denatured alcohol

A shop vacuum with good filters to clean out the canvas sanding dust reservoir on the sander is good too. I can hook my shop vac up to my sander, but the large 2 1/2" hose makes it awkward to use, so I generally don't. If you have a better sanding vac, maybe you could keep the dust down a bit. Although now that I think about it, buying a long smaller hose and an adapter might have made it less awkward.