is the powdery white salt deposit left on masonry surfaces (concrete, brick, stucco) after water evaporates. It typically acts as a severe, destructive force on paint finishes and presents as a cosmetic issue but quickly escalates to causing physical damage by breaking the adhesion between the paint and the substrate.
Simply cleaning the white powder and repainting will not necessarily be successful. The salts might reappear. You must treat the underlying moisture issue (the root cause) first, clean the efflorescence, allow the surface to dry fully (below 15% moisture content measured with a proto meter or below 5% measured with a pin type moisture meter), and then use a breathable and alkali-resistant masonry paint.
High pressure wash to remove efflorescence, loose and flaking paint.
