Efflorescence salts may originate from salts mixed into which components?

• A. Only masonry units
• B. Only mortar
• C. Masonry units, mortar, or plaster
• D. Water source

Answer: (C)

Efflorescence happens when soluble salts are already present in the materials used to build or finish a surface and are carried to the surface by moisture. Those salts can be in masonry units themselves (such as bricks, blocks, or stone), in the mortar that binds them, or in plaster applied to the surface. As water moves through these pores, it dissolves the salts and transports them upward; when the water evaporates at the surface, the salts crystallize as a white powder. Because any of these components can contain salts, the origin of efflorescence can be masonry units, mortar, or plaster, making that option the most complete. Water acts as the carrier, not the sole source of the salts.