What is efflorescence and why does it occur?
Efflorescence is a calcium or alkaline salt which forms as a blotchy, powdery or crystalline deposit on the surface of masonry walls and concrete products. It is due to moisture entering through the walls or the surface of the Cast Stone, combining with the calcium hydroxide in the cement, and bringing the hydroxide to the surface in a solution which forms crystals when it combines with the carbon dioxide in the air. For more information please refer to Cast Stone Institute Technical Bulletin # 33.
