Here are a few more examples of the extreme limited palette; Ivory Black, Titanium White, and Transparent Oxide Red.
At the top is a sketch I did this morning. I wanted to show a little more range in the cooler tones that you can get out of this palette.
The coolest notes are made by mixing black and white, and keeping the brown out of the mix. Well almost, I don't think I have any notes on my painting where I used only black and white - but essentially, cooler means less brown and warmer means less black.
How I put this to use is by assigning functions for different mixes as follows - keep in mind, I'm not presenting a recipe. Just starting points.
The lit side of the flesh is mostly brown and white only. I modulate the value by using varying amounts of white. Highlights (on the cheekbone, etc) approach pure white, but I didn't actually use pure white by itself.
Still in the lit side, I added a tiny amount of black to cool it down toward the jawline. And of course, the beard has more black in it to differentiate it from the warmth of the flesh. Other than that, I didn't use black in the lit side of the flesh.
In the shadow side of the flesh, I mixed more black and less white. Except for the darkest darks, all three colors are mixed in every note. Where it gets a little cooler (shadow plane along the cheekbone) less brown is mixed in. This is a comparatively cool reflected light (ambient light might be a more precise term, but it does the same thing) and as such, I lay it on top of the slightly darker and warmer general block-in color that I have underneath. The idea is that I am illuminating a darker area with a cool ambient light, so it needs to come later in the sequence (you can't illuminate something that's not dark).
Also, there's more black in the shadow side of the beard, again to differentiate it from the flesh not only in value but in temperature as well.
The darkest darks are just black+brown. This keeps these notes not only very dark, but transparent, which is essential for making them not pop forward. After all, the darkest notes are where neither primary nor secondary light reaches. I am careful to keep these darkest notes on the warm side.
On the same paper (these sketches were done on Arches paper) I have a couple of smaller heads to the right, executed quickly. The top shows my start where the shadow areas are blocked in with a wash (a mixture of black+brown+Gamsol. No white, because I want this to be transparent at this stage.)
Then I go to opaque mixes to block in with the general, simplified values of the main areas. Here my aim is to establish the main construct of the head, and get a direction going for the colors (however limited we are in this area with our palette).
From there, I can start adding smaller shapes, shifts in values and temperatures, etc. But even without little details, you can see that it's a pretty representational head.
This was a class demo this past week, and I used the exact same palette. I didn't use a whole lot of the cooler tones, but there's a little bit visible in the left hip area and along the left shoulder and the left arm in the shadow side.
Again, these ambient light planes are laid down after the main block-in. And again, I'm illuminating darker areas (expressed by the original block in), so it needs to be lighter in value than what's underneath. Seems like a simple concept, but you'd be surprised how easily this is forgotten when students revert back to just trying to copy the values that they see.
The whole idea is that the value structure - and now the temperature variations - must be organized, and executed logically. The organization is imposed on the figure, and it can't be done if you're just copying the values.
Hey, that sounds just like the rules in plein air landscape painting!? Have we discovered a golden postulate of representational painting? Probably not. But it does help make sense of the complicated visual reality in front of us.