Better Business Bureau
Angies List 2011

Efflorescence

Efflorescence is a deposit of water-soluble salts upon the exposed surface of masonry caused by the leaching of soluble salts from within the wall. Efflorescence is caused by excessive moisture in the masonry work. When the moisture in the brick evaporates it brings the minerals from the bricks clay to the surface and deposits them there in a form of white crusty powder.  This detrimental appearance is just one of the effects. Much more serious one is hygroscopic effect of salts and minerals. This effect causes efflorescent surfaces to attract even more water, causing increase in pressure in masonry units affected, which may lead to faster deterioration and structural problems. Efflorescence is usually an indicator of water penetration into the masonry structure and can provide a warning before more serious damages take place. Efflorescence can be partially removed by washing the wall with water only, or by washing the wall with water mixed with chemical agents. Cleaning of efflorescence is a cosmetic process and will not prevent reappearance in the future if the underlying problem is not corrected. To stop efflorescence from re-occurring moisture must be kept from entering the wall.