Since it consists of creating an etched or "cratered" surface, I would think that it would have broader application used as a coating on the interior of lens barrels, enlarger lens boards, negative stages, and even negative carriers to decrease the possibility of flare. I personally don't see it used as a means to achieve a deeper black on paper or on the optical surfaces of lenses for the reasons that etching or "cratering" the surface would probably be detrimental to the image.