This layer can be scary because it looks so radical...but it basically what gives the skin its luminosity. Some people start with it but I wait until the surrounding areas are well established before I use any white paint.
I usually save the face until last because the skin tones are determined by what surrounds it.
First, I draw the face in with raw umber and let it dry. Then I begin to use pure zinc white - straight from the tube and build form. Later I begin to use the more opaque titanium white paint.
I don't usually paint over a color (as in the hair) but I realized that I needed to build the light on the face and hair all together.
The face underpainting is finished. It make several days and is a very slow process. It takes as long as it takes. It is necessary to get a likeness starting now.
Here are the finished hands. I always underpaint any skin that shows.
I think that this stage looks scary. It throws all the colors and values off and suddenly the painting looks dark and dreary.
But take heart, it is only a temporary condition.
Next step - glaze.