If your concrete floor has an existing coat of paint, the first thing that you will want to do is an adhesion test:
Existing floor coatings need to be in good condition with proper adhesion to the concrete substrate. Check the adhesion of the previous coating by cutting a small X in the coating using a sharp razor knife. Firmly apply a piece of 5” duct tape over the center of the X cut, and then pull off with a fast snap. If more than 10% of the taped area is removed, the original coating is not bonded well and needs to be removed chemically or mechanically with a grinder before applying RockSolid® Polycuramine® Floor Coatings. If the coating is firmly adhered, scuff sand previously painted or coated floor using 60-80 grit sandpaper prior to coating.
If your floor passes the adhesion test, we recommend our Rustoleum Garage & Interior Floor Primer. It covers approx. 400 sq. ft. on previously coated, sealed, painted, smooth concrete floors and can be topcoated with our EPOXYSHIELD®, ROCKSOLID® or any of our other solid floor coatings after 6 hours.
It is also possible to recoat the floor without priming, however this requires abrasion of the surface in order to ensure a good bond with the existing coating. Rough the surface with 50-60 grit sandpaper and a pole sander / drywall sander to remove the sheen and provide a good profile. Clean off the sanding residue and do a final wipe down with a solvent, to ensure the floor is completely clean, dust free and dry. Acid etching should not be performed on previously coated surfaces, and should be limited to larger exposed areas of bare concrete.