Efflorescence refers to deposits left by salts and minerals as they are carried by moisture from the inside of concrete to its surface and appear as a powdery white coating. The substance can also appear as a hazy film or streaks of white salt. Efflorescence eventually stops after moisture in the concrete has evaporated and is no longer bringing salts and minerals to the surface. Concrete that is always in contact with moisture may not ever dry completely, and cleaning efflorescence from the concrete surface may be an ongoing task.
Put on a pair of latex gloves, a dust mask and safety goggles to keep the efflorescence away from your hands and eyes, and to keep from breathing the substance into your lungs.
Scrub off the efflorescence with a dry, non-metallic, stiff brush. If cleaning a concrete floor or driveway, use a dry, non-metallic, stiff push-broom.
Fill a bucket with 1 gallon of warm water.
Dip a clean sponge into the bucket of water. Remove sponge and wring out excess water.
Scrub off any remaining efflorescence debris with the damp sponge. If cleaning a concrete driveway or floor, pour the water directly on the concrete surface and scrub the remaining efflorescence debris with the push broom.
Saturate the sponge with white vinegar to remove stubborn efflorescence stains. If cleaning a concrete floor or driveway, pour ½ cup of white vinegar directly on the efflorescence stain and scrub with a sponge.
Let the concrete surface air dry once the surface is efflorescence-free.