Efflorescence is a common problem with new masonry. It is often described as a white or ivory chalky-like deposit on masonry walls. Cleanup efflorescence is generally caused by chlorine ions left on the masonry surface by unbuffered acids used in the cleaning process. These ions react with moisture, a calcium chloride substance rises to the surface, and efflorescence is created.
Over time cleanup efflorescence should disappear; that process takes time and leaves an unsightly appearance immediately following construction. A simple way to remove cleanup efflorescence is with EF-Fortless or NMD 80 (4:1). The other option is to use NMD 80 for post construction cleanup, which should eliminate the chlorine ions from the wall and prevent cleanup efflorescence.