Painting Color Over an Underpainting: Part One

The background of the 'Space Reader' painting is close to being finished. For the last few days, I've been working on painting color over the monochrome underpainting. My approach is to mix color that is as close to the underpainting in value as possible, except in the most brightly lit areas, where I am able to apply colors several steps lighter. This adds to the illusion of a bright light source. I've found that I can work much more quickly with an underpainting in place than if I were making a first pass, not only because all the value decisions are already complete, but an artist may also leave an underpainting exposed in certain areas. The result is that one doesn't need to be quite as careful along some defining edges or spend as much time blending into darker areas. An added benefit is that this can lead to softer edges overall, except in the few select spots where I wanted to make them sharper. For the next step on applying an "overpainting" over an underpainting, please proceed to the next step.For more on why I used an underpainting technique for this composition, please see here.