Using a wire brush or scraper, remove any loose or peeling paint from the damaged area.
Use a concrete and masonry cleaner and etcher to clean the surface and mix into pump sprayer.
Using a water-dampened sponge or garden hose, wet the area to be cleaned.
Apply the cleaner and etcher solution to the area with a sponge or pump sprayer. Using a scrub brush, lightly scrub the area to remove the white powdery residue from the surface.
Using a water-dampened sponge or a garden hose, thoroughly rinse the surface.
Allow the area to dry.