What is efflorescence?
Efflorescence is a white, powdery mineral salt deposit that forms on masonry and stucco when groundwater or moisture carries dissolved salts to the surface and evaporates, leaving the salts behind.
When moisture moves through brick, concrete, or stucco and brings dissolved mineral salts to the surface, those salts crystallize as the water evaporates, creating a white, powdery coating called efflorescence. This deposit commonly appears on foundation walls, basement exteriors, brick chimneys, and older masonry in Bridgeport where water exposure is frequent or groundwater is elevated.
Efflorescence signals that moisture is actively moving through the masonry. If a painter applies finish coat directly over efflorescence, the paint will not adhere properly. The chalky layer acts as a barrier between the paint and the substrate, leading to peeling, flaking, and premature failure of the coating. The underlying moisture problem also remains unaddressed, so efflorescence will return.
Before exterior painting on masonry, the efflorescence must be removed by wire brushing, pressure washing, or chemical treatment with an appropriate masonry cleaner. Identifying and stopping the moisture source is equally important. This may involve repairing failed caulk, correcting grading, or installing drainage measures so water does not continue entering the wall.
Addressing efflorescence as part of surface preparation ensures better paint adhesion and a longer-lasting finish on brick and stucco surfaces.