What is Efflorescence?
Efflorescence derives from a French word that means “to flower out” (or so I’ve read). “Flowering out” is a good description because efflorescence is a crystal structure that appears and grows on the surface of concrete, brick, stucco, or natural stone surfaces from the minerals (salts) left on the surface by evaporating moisture.
That is, when excessive moisture passes through a masonry wall and then evaporates from the surface or when surface moisture is absorbed and then evaporates, the minerals within the masonry wall are sometimes brought to the surface with the moisture and there they remain after the moisture evaporates. Over time the minerals align and form crystalline structures that usually appear as white puffy fuzz.
Efflorescence is usually only a cosmetic issue and there are cleaning agents that can be used to remove it from the surface. Sandblasting or blasting with other abrasives can also be used to remove efflorescence. Using water alone will probably remove some of the efflorescence, but it will also drive the minerals back into the wall where they can re-appear on the surface and contribute to the growth of the next “flower.”
Prevention of excessive moisture infiltration or moisture intrusion is a preferred solution.