Calcite is another problem with masonry, especially brick and block, which can be extremely difficult to remove. Calcite appears as a thick whitish deposit which usually builds up over time. It is typically formed when excess moisture evaporates leaving behind a heavy calcium residue.
Efflorescence is a crystaline deposit on surfaces of masonry, stucco or concrete. It is whitish in appearance, and is sometimes referred to as “whiskers”. Efflorescence has been a problem for many years, and is a topic of much controversy.
Manganese is sometimes used in brick composition as a colorant. Manganese staining is a form of efflorescence that develops when moisture in the wall draws salts and color from the brick composition to the surface of the masonry. As the water evaporates, color from the manganese is left behind.
White scum (insoluble salts) is a thin film of hard white/gray deposits formed on the face of the brick or tile. White scum is not the water-soluble, white efflorescence that can normally be brushed away or easily washed off the surface with standard cleaners or a proprietary Sure Klean® cleaner.