I have a painted block foundation: on the exterior I get white salt-like stuff on the surface that destroys the paint — what is this and how can I prevent it?
Efflorescence is often seen as a white fluffy deposit of salt crystals on cementitious wall surfaces. It depends on the presence of salt and moisture. The growth of crystals will continue as long as both are present. The salts are present in the mortar, blocks or concrete structure and the moisture source could be from a variety of locations. When emanating from mortar in brick or block substrates, efflorescence will start as narrow bands corresponding to mortar joints. Some of the causes of efflorescence include failure to adequately prepare the surface by removing all previous efflorescence, excess moisture escaping through the exterior masonry walls from the inside or insufficient curing time for new cement or mortar. If excess moisture is the cause, eliminate the source by repairing the roof, cleaning out gutters and downspouts, and sealing any cracks in the masonry with a high quality, water-based all acrylic or siliconized acrylic caulk. If moist air is originating inside the bui
