Efflorescence is a deposit of water-soluble salts upon the exposed surface of masonry, caused by the leaching of soluble salts from within the wall. Efflorescence is caused by excessive moisture in the masonry work. When the moisture in the brick evaporates it brings the minerals from the bricks clay to the surface and deposits them there in a form of white crusty powder. Efflorescence can be partially removed by washing the wall with water only, or by washing the wall with water mixed with chemical agents. To stop efflorescence from re-occurring, moisture must be kept from entering the walls.