System Three epoxies/adhesives offer a very good substrate for most interior and exterior paints. The epoxy/adhesive should be cured 2-3 days prior to painting. Before painting, wash the surface with warm soapy water. Once dry, sand the epoxy with 150-220 grit sandpaper. Clean the substrate and you're good to go.
Priming is typically not necessary unless specified by the manufacturer. Priming is beneficial when painting with colors that have poor hiding characteristics (red, orange and yellow).