I'm also a beginner. I've been doing a lot of reading, and it seams that it is split opinions on this topic. Half the painters like to put on the epoxy on the bare metal for a protective layer to prevent the filler from absorbing moister and causing rust. The other half puts the filler on the bare metal because it is a much stronger bond, and say they have never had a problem with the filler absorbing moisture as long as it is sealed. What I did is put filler on the bare metal and level as much as I could. As soon as I put my epoxy on, that brought out more low spots that I missed. Then I put more filler on top of the epoxy where needed. So most of the filler is on metal, but I wasn't afraid of putting more on top of the epoxy. I guess I'll see what holds and what doesn't.
