To block the migration of alkali from a concrete substrate, the concrete is often coated with water-based primers followed by topcoats. Until the porosity of concrete is blocked, the chances of migration of alkali exist. Substrate wetting additives play an important role in this condition. They improve the penetration of emulsion paints into the crevices or the pores of concrete and reduce the possibility of alkali migration, which in turn reduces the possibility of efflorescence. The experiments discussed in this article involved applying emulsion paint on a porous substrate, then exposing the substrate to severe water seepage so that alkali could migrate by capillary action to the top of the surface. The effect of substrate wetting additives on efflorescence occurrence was studied.