Efflorescence is a condition where white (salt) deposits form on the surface of the masonry. The formation of salts is usually a sign of excessive amounts of moisture in the masonry. In the presence of water, these compounds gradually migrate to the wall surface, where they remain when the water evaporates.
These deposits are generally not harmful to the building, just unattractive. However, they should be washed from the surface as soon as possible. Some salt deposits are water-soluble for only a brief period after reaching the atmosphere. Carbon dioxide in the atmosphere eventually converts these salts into water-insoluble carbonates, which are impossible to remove without the use of acids.
Read More
