How To Paint Over Stamped Concrete
Stamped concrete is installed with a design imprinted on the surface. Before this or any finished concrete surface can be painted, it must be prepared for the paint, as most paints will not readily stick to a smooth concrete finish.
About the Paint
For high traffic outdoor concrete, most experts agree that an oil based paint is superior to other types. The primer should be oil based as well, which allows it to chemically bond with the concrete. Other types of paint will work, but will not be as durable. For this example, an oil-based paint will be used.
Apply the Acid
Pour out a small amount of the acid solution on the concrete. Using the broom, work the cleaning solution into the concrete. Use as much of the cleaning solution as required to uniformly coat the entire surface. Scrub it into the concrete briskly. The reason for doing this is so that the acid can etch tiny imperfections into the concrete surface, allowing the paint to bond to it later. Allow the generously coated surface to set for at least 10 minutes. This acid can damage your skin, so always wear heavy gloves and avoid direct contact.
Rinse and Dry Thoroughly
Using a garden hose, rinse the surface completely. It is important that all of the cleaning solution is rinsed away, or the primer will not bond to the concrete. Take a few extra minutes to rinse carefully, and then allow the concrete to sit until it is completely dry. Allow at least an hour, but this sometimes takes longer.
Pour a small amount of the primer into a paint tray. Using a medium to long nap roller, apply the primer is long, slow strokes. The etching created by the cleaning solution is filled by the oil-based primer, allowing the primer to bond directly to the concrete, much like soaking into a dry piece of wood. Be sure to apply the primer evenly across the whole surface, and do not allow it to pool in recessed areas.
Apply 2 Coats Minimum
You should apply at least 2 coats of paint. The more traffic the concrete receives, the more coats it should get. Extremely high traffic areas should probably have 3 or 4 coats applied, with considerable drying times between coats. If at least an hour is allowed between coats, the paint cures better, and each coat becomes a miniature layer of protection.
A Note About Paints
The reason oil-based paints work so well with concrete is because they have a fine molecular structure that allows them to penetrate tiny holes created by the acid as it cleaned the concrete. Other types of paint are either unable to penetrate as deeply, or cannot provide a finish that is suitable for the expected traffic. Besides, oil paints stand up to weathering better than other types, and resist fading caused by exposure to direct sunlight.