My wife painted a small bench I had made for her to sit on while feeding our pet rabbits. The bench is painted with an exterior acrylic latex overall and a scene of three rabbits painted in exterior latex enamel and acrylic enamal. It will set on our porch. Is it OK as is or should it be protected with a couple of coats of varnish or something. I'm not sure but I don't think you can cover paint with polyurethane, which is what I have on hand. Any help would be appreciated.