Saturday, May 26, 2007

Color Temperature

Most beginning painters hear about "color temperature" at some point in their education. I did, and it seems a simple concept. Blues are cool; yellows and reds are warm. But, as we all learn, temperature relationships can be a great deal more complex.

For example, temperature is relative. A certain blue next to a certain yellow may appear warm or cool. The rule we learned in our early days is, in fact, more an exception than a rule. Another example has to do with light and shadow. Some painters stick cool blues and purples in shadows as a matter of course, perhaps on the assumption that shadows are always cool. Personal experience does show that it can be 10 degrees cooler in the shade on a hot summer day, but this has nothing to do with color temperature. Sometimes the sunlight is yellow and warm, and we do indeed see the shadows as purplish and cool. But at other times, the sunlight has a cooler quality, more of a yellow-green, which pushes the shadows into a warmer, reddish-purple. Further complicating the issue is cool skylight, which can bounce blue down into the shadows. And what if you have a warm color, such as orange tree bark, in the cool shadows? Life can get quite complicated for a painter.

Lately, I've been keeping color temperature foremost in mind while doing 5x7 oil sketches. I've figured out a sequence of steps so color temperature works for me and not against me:
  • Determine whether the sunlight is cool or warm
  • Verify that the shadow is the complement (and if it's not, re-evaluate the sunlight)
  • Once determined, stick with your determination
  • Push the color relationship (that is, if the light is cool, make it more so, and make the shadows even warmer)
  • Finally, objects in light or shadow, regardless of their inherent warmth or coolness, must always share the temperature (that is, orange tree bark in a cool shadow should be made cooler than you think it is)
By the way, to make colors warmer or cooler, here's what I do. First, I use a split-complementary palette and arrange my colors spectrally, from yellow to red to blue. Then, to make a color warmer, I find where it sits on my palette and then move toward "warm" and add a bit of the color right next to it. So, for example, if I want to warm up my Alizarin Crimson, I add a bit of Cadmium Red Light. The same goes for cooling, only I move in the other direction. to cool Alizarin Crimson, I'll add a bit of Ultramarine Blue. (If a color is as warm as it can be, and I still need it warmer, I will cool down the color adjacent to it on the canvas. Temperature is relative.)

Here are two sketches I did this week. It's springtime, and the sunlight at mid-day, which is when I painted them, is definitely cool. I pushed the temperature relationships to emphasize this and the warmth in the shadows. (As always, you can click on the image and see a larger version.)

"Flat Water" 5x7, oil

"Appletree, Birches & Bluets" 5x7 oil

Post Script: After writing this essay, I had someone ask me for a demonstration in pastel of the same approach. Here, by request, are two pastel. First, Cool light, warm shadows:

"Spring Greens, Dark Firs" 5x7, pastel, en plein air

Now, warm light, cool shadows:

"Maple & Dandelion", 5x7, pastel, en plein air

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