3f2c04aa_ick___Cleaning___Stain_Removal__Description
[Stain] Efflorescence [Cause] The formation of efflorescence requires three conditions: • The presence of soluble salts. • Excessive amounts of water entering the masonry. • The evaporation of water as the masonry dries out, depositing salts on the surface. [Removal] Most efflorescence will naturally disappear over time, however its removal can be accelerated by brushing with a stiff dry brush. The use of a dust pan or vacuum cleaner to collect the salts after brushing is recommended as this will prevent salts from re-entering the brickwork or any porous paving materials below. [Description] 
Efflorescence is not a stain, it is a powdery and sometimes 'fluffy' deposit that forms on the surfaces of porous building materials such as masonry units, mortar and concrete.
Brick | Cleaning | Stain Removal
Description