efflorescence definition chemistry
Secondary efflorescence on the dam of the Robert Moses Niagara Power Plant. In chemistry, efflorescence (which means to flower out in French) is the migration of a salt to the surface of a porous material, where it forms a coating. The essential process comprises the dissolving of an internally-held salt in water, or occasionally in another solvent. The water, with the salt now held in solution, migrates to the surface, then evaporates, leaving a coating of the salt.