When striving to get our lightest values light enough, the temptation is to substitute white for a more accurate color. Although this practice is both expected and acceptable in watercolor, since the lightest tones are actually taking advantage of the brilliant white of the underlying paper.
But in oils, the practice of using white, straight from a tube, isn’t so successful. For one thing, tube white (usually titanium white these days, since zinc white tends to yellow with age and become brittle) has a cool cast, which doesn’t ring true as a highlight for warm colors. For another thing, unless the subject color is intentionally white, pure white paint seems to glare and stand out unattractively from the rest of the composition.
The only unmodified white in the painting below is in the highlights on the paper towel roll (behind the canvas on the easel), and the highlights on the blue-white gloves, shoes, and turps can. All other “whites” have been modified.
So what’s the answer? As with mixing any other color, it’s a question of blending the appropriate hues to achieve the desired value. And when that desired value is almost white, the mixture may require only the tiniest quantity of pigment to modify the tube white.
As I’ve been familiarizing myself with oils, I’ve found that my lights don’t always get quite light enough. What I think will be a light tone, like the highlights on the hair in the painting above, proves to still be close enough to the middle tones to undermine my intention. In this case, the highlight on the woman’s hair was so similar in hue, value, and saturation to those of the canvas that her head (which should have been a secondary focal area) and the canvas appear to merge into a single shape, which in turn disappears into the foliage behind them.
A few slight modifications to “En Plein Air” (#160409-o), below, made a big difference. I lightened the hair highlights a bit, and both slightly lowered the value and increased the saturation of the canvas, which served to separate the two shapes, bringing greater attention to the head and allowing the canvas to appropriately replicate the colors of the background.
The difference such subtle changes in contrast can make demonstrate for me again how important it is to really understand value control, even in the highest range, and to practice monitoring those values closely as I prepare the colors on my palette. I didn’t have to worry about the lights so much when using watercolor. I’ve been learning that it’s much more critical when working with oils.