Lately, I've been doing more and more 'brunailles', in other words, three colour paintings usually made in order to establish tone before glazing over with colour. I was captured by how much expression can be made without very much colour at all.
Also by the way the light pigment (in these cases, Sennelier's Warm Bright Yellow) seems to almost emit light. These old nurse's uniforms look fantastic where the white parts are represented thus.
You can 'tip' the emphasis from cooler to warmer greys by adding more ultramarine or burnt sienna to the three colour mix -as you can see in the warmer, redder cast to the second painting.