Phantom Lighting

What if you could use phantom membranes on light sources, e.g. glowstone, and doing so dims the light coming off of the source by one light level per membrane (by looks alone it seems like phantom membranes could diffuse light), and you could go all the way down to no light. The block itself could glow less and less as it’s light level goes down. If you want to increase the blocks glow factor, but not it’s light level, you can gradually increase it by using glow squid ink. If you want to increase the blocks brightness, say… buff it, you can use wax on it to gradually increase its light level. The method of altering the light sources is the way you use wax to wax copper (simply right clicking the block while holding the appropriate item). I am trying to think of a way you can decrease just the block’s glow factor, i.e. not have it’s brightness decrease as well, but I cannot think of the right item for it. Any suggestions? Perhaps ghast tears? I think that’s the most appropriate choice, given it would only decrease the block’s glow (so coal wouldn’t make since because it would logically lower the sources light level as well, and make the block black).