Masonry facades

Efflorescence is the process of the dissolution of salts by moisture and their deposition on the surface of a material as crystals as it dries out. Severe efflorescence produces an unsightly white bloom on brickwork.

Where efflorescence occurs below the surface of a material it is termed crypto-efflorescence. This is more damaging as it can cause face spalling of brickwork rather like damage arising from frost action. If the salts crystallise below the surface (within the pore structure) they exert a tensile force that is strong enough to disrupt the surface of the brick.

The salts of sodium or calcium are relatively harmless, but potassium salts can be very damaging to brickwork when they occur in a crypto-efflorescent form. The problem is sometimes associated with rapid drying of water that causes the salts to crystallise. The source of salts could be from external influences such as sea spray, the coal used to fire the bricks, contaminated mortar, etc.