Stamping, or adding a pattern to concrete, adds visual interest to an otherwise smooth surface. While the stamping can give the concrete a decorative look, it doesn't change the original color unless a stain is applied at the time of installation. A coat of paint, however, can change the look and feel of a concrete surface and help make the stamped design stand out. It is possible to paint over both plain gray and colored concrete.
Test the moisture content of the concrete by taping an 18-inch square of aluminum foil to the surface for 24 hours using duct tape. If it is fairly dry upon removal, the concrete has cured enough to be painted; but if the foil is wet, the concrete needs to cure longer before being painted.
Scrub the concrete with trisodium phosphate, taking care to remove all traces of dirt, oil and mud.
Rinse the TSP completely by spraying with a garden hose or power washer and let the concrete dry.
Apply a concrete etching solution, using a long-handled scrub brush to reach into crevices of the stamped design.
Allow the etching solution to sit, following the manufacturer's directions. This is usually around 20 minutes.
Rinse the concrete thoroughly, paying special attention to grooves, and then let the concrete dry completely.
Apply a thin coat of primer designed specifically for concrete. Use a large brush or roller for large flat areas and smaller brushes to reach into crevices and grooves in the design.
Wait for the primer to dry completely, according to the manufacturer's directions. In most cases, this is around eight hours.
Brush on a thin coat of paint designed for concrete or masonry, taking care not to let the paint pool in any of the depressions in the concrete.
Allow the paint to dry. This normally takes at least four hours.
Repeat Steps 9 and 10 to apply a second coat of paint.