The object of barrier coating is to build up an epoxy coating that provides an effective moisture barrier and a smooth base for final finishing.
Apply second and subsequent coats of epoxy following the same procedures. Recoat when the previous coat is still tacky (about as tacky as masking tape). To avoid sanding between coats, apply all of the coats when previous coats have cured to this tacky stage. After the final coat has cured overnight, wash and sand it to prepare for the final finish.