Mountain Interior, 7x12, oil - $100 - contact Michael
A reader writes: "I notice that some plein air painters have lots of 'air' and translucence in their shadows, but still have (what seems to be) accurate and expressive values."
One of the beauties of painting in a medium such as oil is that is has both opaque and transparent qualities. Opaque/transparent is one of several contrasting pairs that give a painting punch when used well. Typically, and especially with oil, you'll see painters keeping darks and shadows transparent, while saving more opaque paint for the lights. Keeping darks transparent helps create an illusion of depth in the shadows. Keeping lights opaque helps bring highlights forward.
If you paint on a white, untoned canvas, the paint can even become transparent enough to mimic the "stained glass" effect of watercolor. Light shines down through the paint, bounces off the white ground, and passes back through the paint a second time, giving the layer a beautiful, luminescent quality.
One of the problems, though, is in keeping these transparent darks dark enough, especially when using a white, untoned ground. I've also noticed that some pigments, especially ultramarine blue, may actually become lighter as the oil sinks into the ground. Sometimes the darks need to be repainted to make them dark again, or the lights need to be lightened. Keeping track of value shifts is just one of the balls we painters need to juggle while painting.
I sometimes add white - or a light mixture of palette scrapings or mud, which contain white - to my darks to make them somewhat more opaque. Then I brush them into the shadows thinly. The result is a semi-transparent layer that has some of the "stained glass" effect but also the staying power of a more opaque layer. (See the sketch above for an example.)
By the way, I use a modified split-primary palette of colors in which my darks are all transparent. The colors are: cadmium yellow light, cadmium yellow deep, cadmium red light, permanent alizarin crimson, ultramarine blue and phthalo green. My white is a titanium-zinc mixture. (All the colors are from Gamblin.) There are many other palettes that a painter can use, and I'm sure, many ways to get air and translucence in the shadows while maintaining accurate and expressive values.
On another note, I still have space in the April Grand Canyon workshop. You can find out more about it here. Also, if you haven't taken my survey, I'd love for you to do so. That link is here. Finally, I'm off to Tubac, Arizona, to teach a workshop this week, so I doubt I'll blog again until I return. Mind the shop!