Prepared port side aileron and elevon surfaces by sanding orange peal and small bubbles with 320/600 grit on cordless 5" sander. Orange peal and small bubbles were a result of a long (>24 hr) pot life using Eastwood Optiflo roll-on epoxy.
Used extra pieces of hinge to mask control surface hinges from excess epoxy from hinge pin. Used two cans of Eastwood two part epoxy (https://www.eastwood.com/ew-2k-aerosol-epoxy-primer-gray.html) on hinges and channels to coat places that aren't conducive to a thick coating with roll-on primer to bind hinge and pins. Spray epoxy set rather quickly. The the masking hinge pieces were removed and hinge pins cleaned of epoxy residue with acetone.