Contact the manufacturer of your epoxy. They'll know.

If you do your painting with something like Dr. Ph. Martin's concentrated watercolors (they're liquid, not tubes) it would be no different from the dyes people routinely use under epoxy without problems. WIth the absorption into the wood you'll want to test. Gouache is probably your next best bet. It's a type of opaque watercolor. Acrylics would be your next best bet if you don't want your media to be absorbed into the wood like watercolor, but I'm not sure how the epoxy would adhere. It would be like putting epoxy over house paint. The difference with artists' acrylics (a good brand like Liquatex) is that they can be easily thinned to nearly the same consistency as watercolers. I think if you worked at it, the concentrated watercolors would give you a really vibrant and interesting effect, because you could do it so that the wood grain showed through.

Whatever you do, don't use oil paints. Epoxy won't stick to anything with oil in it.

The last caveat is that all paints, even acrylics, will degrade when exposed to UV light. Using high quality artists' colors will help slow it, using UV filtering epoxy and varnish will help as well, but it's an inevitably.

Good luck!

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