Following the method illustrated in the 1917 book The Practice and Science of Drawing, by Harold Speed, I tried the mass drawing (aka painting) of a head maquette. At the same time, I used another approach to paint a classic plaster cast I bought recently, illustrated in the Oil Painting Techiniques book, which we are discussing at Gurney Journey
The first method (on the left) is pretty simple: after laying down the base drawing in pencil and fixing it, you mix up a dark, mid, and light value with Raw Umber and white. I thinned the mid (ground) value down a lot with some Liquin, then scrubbed it across the whole surface. I then came in with the white, while the ground was still wet, and let the paint on my brush freely mix with it. This way, I had to use thicker paint to get the lighter values.
It’s a great exercise that helps you learning how to lay down paint, control its thickness, and think about strokes ahead. I then did the same with the dark, and came back in with the mid in a thicker version to fix thin spots.
Speed insists on the fact that you should keep lights and darks as separate as possible, so avoid letting them ever touch.
The second method (above right, and below), illustrated in the Oil Painting book, relies strictly on laying down very thin, yet opaque paint. Tones must be kept simple and arranged in large areas, while details must only be added after establishing the main masses. Overall, I prefer this latter method.