Stucco, brick, and other masonry surfaces may develop a white powdery substance on them known as efflorescence. You can brush away this powder with a wire brush, but unless you eliminate the cause, it will return—and its existence may indicate that more serious moisture damage may occur.

Efflorescence can be caused by heavy moisture in your climate or by moisture from poor drainage, roof leaks, sprinklers, and the like that can penetrate masonry surfaces.

You can clean efflorescence by washing it and scrubbing it with a brush. If the surface is grimy, use a little tri-sodium phosphate (TSP) in warm water. Be sure to rinse away all of the TSP or it may leave a residue or stain.