Our company is building interior concrete masonry walls in an office building where lighting will shine down the painted surface. On the first area completed, the architects did not like the fact that you could see variations in the masonry wall. The variations were actually very small, generally less than 1/16 inch from one block to the next; however, the down lighting emphasized even small variations.
What can be done to correct this problem?
Lighting the wall in this way emphasizes any small variations of the mortar tooling depth or out-of-plane variations of the units within the wall. These variations may become noticeable even if the wall is built with tolerances far exceeding those of typical masonry construction.
Probably the best way to avoid this problem is to change the lighting system to an indirect approach, rather than washing across the wall along the top edge. In areas not yet built, intentionally increase the texture of the wall. The resulting shadows can create an interesting aesthetic.
Short of changing the lighting or emphasizing the texture of the wall, there is little that can be done to create a uniform appearance on a painted concrete masonry surface. If the appearance is objectionable, another solution is to abandon the exposed masonry appearance and apply plaster to the face of the wall to create a smooth surface.