Hi, Steve

I've always painted directly onto the epoxy after wiping the surface with acetone to ensure a clean, dust free and very dry surface. I then varnished everything but the painted surface because the varnish tends to tint the paint with its typically yellow hue. I use Tremclad Rust Paint with electrical tape to edge the areas to be painted. Electrical tape works well, especially since you can bend it around curved images and still get good adhesion while painting. The tape does let go after a few hours where stressed. The Tremclad is very workable after setting as it is relatively soft for a couple of days. Once it hardens it's very difficult to damage. In three years I've had no problems with paint adhesion. The Tremclad provided very good UV protection which is why I chose that brand.

My $0.02.

Robert N Pruden