How to Clean White Efflorescence from Bricks and Concrete
Efflorescence is a white deposit of water soluble salts that can appear on masonry bricks. It can be a fine powdery substance or a crystallized buildup. Depending on the type of salts present it can also appear green, brown, or yellow. Efflorescence happens when soluble alkalis are present in the brick or grout and moisture is able to penetrate the brick forcing salt deposits to the surface. This can happen a month after the brick was laid or as long as a year later.
To clean efflorescence from bricks a chemical cleaner or efflorescence remover can be used. A good mildly acidic soap solution type of cleaner can work well depending on the severity of the salt buildup. In some cases the use of a pressure washer is not necessary. It can be a simple spray on process that eliminates the efflorescence salt deposits from the brick.
In extreme cases where the calcite type of crystallized buildup has occurred, appearing as an ivory colored very hard substance, a calcite presoak may have to be applied several times prior to using an efflorescence remover. If a pressure washer is needed to aid in efflorescence removal, be cautions of using too much pressure which can damage the mortar joints.
Sandblasting can also remove efflorescence from bricks but can also leave the brick surface more porous and prone to additional efflorescence problems.
Cleaning efflorescence from brick will not cure the problem meaning it only cleans the surface of the brick but will not stop efflorescence prone bricks from re-depositing more salts on the surface. Moisture entering and mixing with the soluble alkali sulfates in the brick is what causes the efflorescence problem. At this point all you can do after cleaning is to prevent moisture from entering the bricks by applying a brick sealer.
Before sealing bricks it is important to be sure they are completely dry. Allow the brick surface to air dry for several days after cleaning efflorescence. Otherwise you may trap moisture in the brick which would promote efflorescence from reoccurring underneath the sealer.
Cleaning efflorescence from bricks is not difficult with the right brick cleaner and a little patience. Be sure to follow the directions on the efflorescence remover that you use and to apply a good brick sealer once the surface has completely dried.
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