I think one of the Lightroom colored filter effects would reallllly help this. I often just click through the Lightroom color filter effect options, and look at yellow, green,red, blue filter effects, and if I find one that has potential, I will then adjust the exposure levels, and often times the effect of the right filter is almost miraculous. The problem here is that the paint brush bristles and the sponge both have the SAME tonal value, which is what represents color in B&W...so the effect is rather monotonous.