I wonder how safe the use of boron nitride is: I understand it can irritate lung tissues so coatings containing it should probably not be sanded.

Yup, I agree. Of course a dust mask is mandatory for sanding epoxy tho. Graphite dust isn't good for you if directly inhaled either. I would guess that when the particles have been fixed in epoxy, the inhalation risk might not be much worse than for epoxy dust generally. Wear a dust mask, and have good ventilation. Probably most dangerous if you were to inhale a load of graphite or boron nitride directly before it had been mixed with epoxy.

But it would be preferable to have a finish coat that was attractive, easy to maintain, provided UV protection for the epoxy and that did not require finish sanding. And while I could presumably get a whitish color from boron nitride (?) I like the various colors of the airboat coating. I'm also hoping from the sales literature that the airboat coating might be lower VOC, and easier prep and cleanup than marine paint, which would be the obvious alternative. Curious about that if anyone here has tried it...

--
Ogata
eric