Efflorescent
In chemistry, efflorescence (which means "to flower out" in French) is the loss of water (or a solvent) of crystallization from a hydrated or solvated salt to the atmosphere on exposure to air.
Efflorescences can occur in natural and built environments. On porous construction materials it may present a cosmetic problem only, but can sometimes indicate serious structural weakness.
Read more about Efflorescent: Examples, Primary Efflorescence, Secondary Efflorescence, Protecting Against Efflorescence, Image Gallery