Just the backs and edges, yes. The fronts are fine as they are and ready for the clear coat. The castings are 'raw', though, which means they still have an uneven meniscus or lip of resin around the edge on the backs (what would have been the top of the casting, open to the air). That needs to be sanded down so the backs are level and flat for the grips fit correctly. Wet sanding with progressively finer grades of abrasives will do this, but you do need to go to really fine grades at the end (12,000 or so) and then polish the backs and edges before final spraying with the clear coat to bring back the clarity of the clear resin all the way through. Hope this helps.