At Valley Performance Coatings we prefer to use a mechanical method to prepare the surface of concrete to be coated. This will insure a proper profile for the epoxy to bond to the surface. The ideal profile is 2 to 4 mills . [similar to a 60 grit sandpaper] This is defined by measuring the peaks to the valleys in the cross section view of the concrete.They range from CSP 1 [ nearly flat ] to CSP 9 [very rough] for thicker self-leveling or polymer overlays, acceptable profiles generally range from 4 to 6. Achieving surface profiles in the higher ranges often requires roughening by shotblasting or scarifying.