A Note on Efflorescence Efflorescence is a salt deposit that forms on the surface of concrete, masonry, clay brick and porous stone. It causes unsightly white stains which can be particularly objectionable on colored concrete. Water, concrete permeability and soluble content determine how much and when efflorescence will occur. Seal against water and stop leaks. Keep de-icing salts away.
Efflorescence is easy to remove with water wash if caught early.
If not, it converts to calcium carbonate which is removed with a dilute acid wash that will affect the surface appearance.