I used to use a foam roller and held it in my hand to spread the varnish. The coats weren't the best looking. Eventually I gambled on a foam brush and managed perfect coats with no runs at all. I used Z-Spar adn applied thin coats, maybe 4-5 all together. Aside from a bumpy finish because I was in too much of a hurry to sand the epoxy smooth, it looked great. I believe I used a three-inch brush. I doubt I'll ever use any other method to apply the varnish again, it was too easy.

My $0.02.

Robert N Pruden