Epoxies applied to galvanized surfaces will soon peal off. If galvanized surfaces must be coated, be sure to use an approved primer. For reasons not known to the author, aluminum is also another metallic surface that epoxies sometimes have a difficult time getting a good bond to. Fisheyes are areas on a painted surface where the coating literally pulls away for the substrate leaving a coatingless void or fisheye. Often fisheyes are caused by surface contaminants such as a bit of silicon, wax, or oil.
Surface tension plays a big part in fisheyeing.
There are some additives that can be mixed into the epoxy that will reduce surface tension. Likewise, on wood, applying several coats of solvent thinned epoxy, instead of one coat of unthinned epoxy, seems to work well. Applying a thick coat of epoxy over a contaminated fisheye surface will bury the fisheye but expect the coating to peel away in the future. As a rule of thumb, always suspect some sort of surface contamination as the primary cause of fisheyeing. Pinholes are similar but caused by expanding air bubbles under the still soft epoxy.