Efflorescence is the white substance that may build up on the surfaces of unsealed concrete. It is caused by migrating moisture that brings soluble salts to the surface. Efflorescence is very normal, but is noticed more on darker colors like Graphite and Cocoa. To best minimize any chance of efflorescence, we recommend adding either of our penetrating, breathable sealers. Efflorescence is not a manufacturer’s defect and as such, is not covered under Jackson Cast Stone’s product warranty.