During construction, water gets inside a wall system and causes initial efflorescence, or “new building bloom.” Remain calm: the wall will dry and the efflorescence will go away.
Powdery or chalky white deposits or stains sometimes appear on the surface of masonry buildings. Called “efflorescence,” these deposits occur when water reaches and dissolves soluble salts within the wall, migrates to the surface, and evaporates. Soluble salts may be present naturally in the masonry units or mortar materials, or they may be carried into the wall through rain or groundwater. Water, of course, is present in fresh mortar. Some of the water is used in the cement hydration process as the mortar hardens and bonds the masonry together. The rest of the construction water slowly makes its way to the surface and evaporates, sometimes causing efflorescence.