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Monday Morning Art School: color temperature and palette

Mixing paints is simple if you understand how pigments work.

Tilt-a-Whirl, by Carol L. Douglas, plein air.

In theory, you can paint with just four pigments: red, blue, yellow and white. For beginning painters this is sometimes a good idea, because it’s the fastest way to learn color management. It simplifies the thought process so you have only one decision to make at a time, and it is easier to get a more unified color scheme.

But there is a big limiting factor, and that’s the impurity of pigments. They all have overtones that muddy them up in certain mixes. That’s why your local paint dealer uses many, many more pigments than just red, blue, and yellow.

Split the color wheel in half like this and you have your cool tones on one side, warm ones on the left.

Claude Monet’s palette shifted over time, but included these paints:

  • Chrome yellow
  • Cadmium yellow
  • Viridian green
  • Emerald green
  • French ultramarine
  • Cobalt blue
  • Madder red
  • Vermilion (red)
  • Flake white
  • Ivory black (before 1886)

These are sets of paired pigments. That means he has a warm and a cool of each color, plus black and white. 

I use paired primaries as well, omitting the green but adding in some other earths. (Here are my supply lists for oils,  acrylics, and watercolors.)

The distinction between warm and cool colors has been important in painting since the Impressionists. Warm colors are said to be hues from red through yellow and cool colors are said to be the hues from green through violet. Each hue around the color wheel also has a warm and a cool version.

Paired primaries from my palette.

There’s no factual hot or cold point because this is just a poetic description that works. Much of what we believe about the psychology of color is hocus-pocus, but it’s true that if the light is what we call “warm,” the shadows are what we call “cool,” and vice versa.

Winter sun along my hedgerow, by Carol L. Douglas, plein air. If the light is warm, the shadows are cool, and vice versa.

When we say that lemon yellow is cooler than cadmium yellow deep, we mean that if you are trying to mix a greenish yellow, you’ll get a clearer shade with the lemon than you will with the cadmium yellow deep. The warm-cool language is just a convenient way of saying that.

Different pigments may look the same when squeezed out of the tube, but there the similarity ends. Pigments are impure, and you have to learn and work around those impurities.

Three blues that look similar out of the tube, but behave very differently. The ‘glaze’ on the left is the undertone. Courtesy Gamblin paints.

Mass tone is the color a pigment is straight out of the tube, dense and unmixed with another color. No real-world pigment, however, is as pure as a color on a video screen. While two pigments may look the same to the naked eye, their behavior when mixed can be radically different.

Undertone is the color revealed when a paint is spread thin enough that light bounces back up from the substrate. Some pigments are fairly consistent when moving from mass tone to undertone. Others have significant color shifts. Not understanding those undertones tones can lead to muddy mixes.

Cadmium Red Hue is usually made with napthol red and a little white. They mix very differently, which is why the hue is a bad substitute for the real pigment. (In its own right, napthol is a fine red, however.) Courtesy Gamblin paints.

Ultramarine, Prussian and phthalo blue are colors that shift radically from mass tone to undertone. They’re all so dark out of the tube that their differences aren’t apparent to the naked eye. But dilute them, and you’ll find a wide range of blues.

Undertones are why buying “hues” instead of pure pigments can be such bad value. Take, for example, cadmium red hue, which is usually a napthol red with a small amount of white added. Out of the tube, the two paints are indistinguishable, but they mix very differently.

To see a pigment’s mass tone, put a small dab of paint on a smooth white board or glass palette and draw it down with a knife, creating a uniform, solid stripe that completely obscures the painting surface.

To see the undertone, draw the sample down again so it is translucent. You should be able to see minute variations in the color, and in the covering power.

Click to get a printable PDF

Another way to test colors is to mix through what you have on your palette. Make the above color chart, using three sets of paired primaries:

  • Prussian blue—Ultramarine blue
  • Quinacridone violet—Cadmium orange
  • Indian yellow—Lemon yellow

The purpose of this exercise is to understand how paired primary pigments work together, so that you can make neutrals when you want them, and avoid mud when you don’t.

Draw the chart onto a canvas, and then mix across and down for each square. When I say “mix”, I mean mix them before applying, rather than in the squares themselves.

The left column and the top row should be pure pigments. Fill it in, then, just like the multiplication tables of your youth. For example, the intersection of cadmium orange and ultramarine blue should be a 50-50 mix of those two colors.

If you’re painting in watercolor, use enough water to make a jewel-tone transparency. In oils, the results should be opaque.

Monday Morning Art School: four color exercises

By the time you’re done with these exercises, you’ll have lots more experience in mixing color.

Our basic classroom still-life for these exercises. 

Above is the still life I created for these exercises. Make your own, or work from a photograph. You can use the same subject for all four exercises. Keep it simple; it doesn’t pay to get lost in the details when you’re supposed to be thinking about color.

Mimicking the masters

The Starry Night, Vincent van Gogh, 1889, courtesy MoMA
What’s your favorite painting? Look carefully and mix the basic colors in it. One student referenced The Starry Night, above, for her painting, below. 
Jennifer’s painting based on The Starry Night.
The goal is to use those colors in various positions in your own painting. That means substituting Van Gogh’s blue for the blue in your painting, etc. You don’t need to use the same proportion of colors as Van Gogh used; just use them in your painting. If a color in your painting doesn’t appear in the picture you are mimicking, work around that. Don’t mix to approximate what you see.
Olive Trees with the Alpilles in the Background, Vincent van Gogh, 1889, courtesy MoMA
Van Gogh painted a series of olive trees in 1889. One of these, Olive Trees in a Mountainous Landscape, (above) was a complement to The Starry Night. You can see how he manipulated the palette (and linework and composition) to relate the olive trees to the night sky.
Color triads
For this exercise, I refer you back to this blog post on color harmonies. Re-read the section on triads, because you’re going to use either an equilateral triad or a harmonic triad to build a painting.
Mary’s color triad painting.
The easiest triad to use is a primary triad. The still life at top was set up to include primary triads and secondary triads, depending on which objects students emphasized. They started by choosing a dominant color and then from that, subservient ones. For example, one might base the painting on the cobalt of the blue vase, with the yellow bowl and red apples subservient to the blue.
Harmonic triads are not balanced, but are counted 3-4-5 in either direction on the color wheel (as in the section on triads). Again, mix a dominant tone, and then its subservient tones. Your goal is not to match the real colors in your subject; your goal is to substitute the color palette for what you see.
This, plus white, is a limited palette.
Limited palette
In theory, you can get to any color using just red, blue, yellow and white paint. But the chroma and clarity of those mixes depends on the pigments you start with. For example, cadmium red mixes brilliantly on the orange side, but muddily on the blue side.
Limited-palette paintings tend to be more unified than broader-palette paintings, precisely because you can’t hit all the points in the color wheel.
My limited-palette demo using the paints above.
The classic color pigments are cadmium yellow, cadmium red and ultramarine blue. You’ll need white as well. Don’t buy extra paints for this exercise; use what you have that’s closest to these colors.
Hardwood, by Carol L. Douglas. This is a color substitution painting.
Color substitution
The painting above is a kind of substitution painting, but we’re going to use a narrower interpretation of the idea. We’re going to substitute each main color for its complement on the color wheel.
Olive Orchard with a Man and a Woman Picking Fruit, Vincent van Gogh, 1889, courtesy Kröller-Müller Museum
In Van Gogh’s olive tree painting, above, he’s substituted a warm gold for a blue sky. We’re going to do the same thing, except we’ll do it everywhere on the canvas. Keep the value and chroma the same as the original color, but substitute the complementary position on the color wheel. It sounds simple, but it’s devilishly difficult. Have fun!