Epoxy long term test:
I have been spraying DPLF epoxy primer for a few years now. You can get it in five or six different colors. It cures out to a beautiful even satin sheen and bonds like crazy I have been tempted to not paint over it. Anyway I did an experiment. I sprayed the black primer and the white primer on a piece of aluminum and let it sit outside for the past 16 months. The white primer yellowed some and the black primer faded a little. Both of the colors were still bonded to the aluminum great but with one wipe of a wet towel the top surface smeared off. As rust master stated the UV from the sun eventually breaks down the epoxy primer.
