When planning to paint bare metal with an epoxy, make sure you are applying the epoxy directly to properly cleaned and sanded bare metal. Do not use an etch primer. Residual acid from the etch primer can interfere with the proper curing of the epoxy. This may lead to extended dry times, potential blistering and even adhesion failure.
Always follow the recommendations on the product data sheets for best results! Your paint job will be better for it!