Bricks naturally contain water-soluble salts. When moisture penetrates the brick, salts make their way to the surface and when the water evaporates, a white powdery substance containing salt is left behind. Water from behind or underneath the brick, poor caulking, bad flashing or underground water migrating up can cause efflorescence.
How to Remove Efflorescence
Removal of the white powder depends on what phase the “flowering” is in. In its earliest phase it can be removed with water and a bristle brush. After it has become insoluble, a mild acid solution can work. The Masonry Institute of America has seen good results using muriatic acid in a mild solution. Rather than one big dose, several mild applications are recommended. Thoroughly rinsing the area with clean water is very important. Other commercial products are available but must be applied properly to get good results.
Note that cleaning efflorescence will not end the problem. It will reappear unless the natural process of efflorescence is stopped.
How to Protect Against Efflorescence
To protect against efflorescence, people often try using a sealer that repels water and penetrates deep into the brick. However, in Chicago, sealers may actually lead to damage from the freezing and thawing cycles. Vapor barriers, sealers and coatings should be assessed for your conditions. Instead, reduce excessive moisture exposure with copings and flashings. Keep garden hoses and sprinklers away from the brick.
Brick discoloration from efflorescence is a cosmetic problem caused by a natural process. However, excess moisture that causes efflorescence can also cause more serious brick problems over time. Add brick maintenance to your spring cleaning list to keep your brick looking beautiful. Pay attention to water issues that could turn into more serious brick problems.