Epoxy primer is a great way to seal bare metal. The key is to put it down, and then apply a build primer over it. Do not do body work on the epoxy primer. Each manufacturer will recommend different things I'm sure. I used PPG DPLF epoxy primer on my truck. It's non sandable, and must be coated within a week. I sprayed it on, waited 24 hours, and then shot it with PPG K36 build primer. I then did my body work, etc, sanding the K36, never the epoxy primer. A good way to do this is to get your build and epoxy primer in different colors. Makes it real easy to see if you are sanding down to far.
