page_title: Efflorescence
hierarchical_section_title: Efflorescence
caption_attribution_description: English: Secondary efflorescence emanating from the Robert Moses Niagara Hydroelectric Power Station, weakening the concrete by dissolving the cement stone.
context_page_description: In chemistry, efflorescence is the migration of a salt to the surface of a porous material, where it forms a coating. The essential process involves 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.
  In what has been described as "primary efflorescence," the water is the invader and the salt was already present internally. Some people describe a reverse process, where the salt is originally present externally and is then carried inside in solution, as "secondary efflorescence." However, others would give this latter phenomenon another name entirely.
  Efflorescences can occur in natural and built environments. On porous construction materials it may present a cosmetic outer problem only, but can sometimes indicate internal structural weakness. Efflorescence may clog the pores of porous materials, resulting in the destruction of those materials by internal water pressure, as seen in the spalling of brick.
context_section_description: 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 involves 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.
  In what has been described as "primary efflorescence," the water is the invader and the salt was already present internally. Some people describe a reverse process, where the salt is originally present externally and is then carried inside in solution, as "secondary efflorescence." However, others would give this latter phenomenon another name entirely.
  Efflorescences can occur in natural and built environments. On porous construction materials it may present a cosmetic outer problem only (primary efflorescence causing staining), but can sometimes indicate internal structural weakness (migration/degradation of component materials).  Efflorescence may clog the pores of porous materials, resulting in the destruction of those materials by internal water pressure, as seen in the spalling of brick.
caption: Secondary efflorescence on the dam of the Robert Moses Niagara Power Plant.
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