I'm curious as to what the optimum finish on an aluminum surface should be that will ensure a powder coat will hold the best? Say you have a cast aluminum part that you plan on powder coating, but you want the part to have a nice, even, "slick" appearance so you decide to sand down the cast. At what grade of sandpaper would you stop the sanding process? If something has been show polished, will it need to be roughed up before coating? Any help would be appreciated.
