handprint : intuitive color study

intuitive color study

Any painter with the technique to manage color design and mix paints effectively has an understanding of color. How does the painter gain that understanding? Through experience rather than abstract concepts — a process I call intuitive color study.

"Intuitive" means, "obvious from experience". It's color mixing without the intellectual baggage, especially the "primary" color baggage.

I have watched my own color mixing — I mean, paint mixing — habits, identified areas where paint mixing seemed harder or easier to understand and control, and clarified how I plan a color mixture or color design. This page summarizes what I know.

the guiding ideas

The essential facts of color are found in the behavior in paints rather than in the abstract, geometrically perfect rules of "color theory". Abstract concepts either break down in the specifics of paint mixing (leaving the student even more confused and bewildered than before), or they encourage the student to mix with his concepts instead of his eyes.

The first guiding idea is to let your eyes do the talking. "Color theory" does not act as a law of nature to determine the behavior of paints. Paints just do what they do as material substances, and "color theory" comes as an after the fact explanation. Look at what paints do, and learn from it.

The second guiding idea is to think of the palette as a gamut, a limited range of color mixtures determined by a specific choice of paints, and not as impure or tainted colors standing in for ideal colors that exist in an abstract and perfectly symmetrical geometry.

The third is to think of the palette as an abacus, which can produce consistent and trustworthy results from the correct manipulation of its parts. Mixtures of palette paints are the movements that are necessary to get the correct paint mixing result in a specific situation. (This idea is explicit in the color mixing discussion found in Jean-Louis Morelle's Aquarelle: L'eau creatrice.)

The last guiding idea is that you learn to paint by adjusting something familiar to get something unfamiliar, as an act of improvisation: artists don't "predict" color mixtures, they become better at anticipating what paints will do. This means learning through experience that some paints make less obvious mixtures (blues from purple and green) or create unexpected but useful new mixtures (browns from magenta and green).

technique

the guiding ideas

color study principles

The focus is on physical paints, not on abstract "colors"; the goal is to learn paint mixing concepts, and not get distracted by "color theory" concepts. No magical qualities, no eternal essences, no special color symbolism — just a practical choice of available paints. Colors are "primary" only in terms of artistic goals: they either produce the mixing effects you desire, or they don't.

color study principles

Here are my intuitive color study principles. I've arranged them to highlight that some principles are the foundation for others. The most effective way to teach paint mixing depends on the student, but I believe the emphasis should always be on experience with paints, and abstractions derived from experience.

Care should be taken to distinguish consistently between hue and color, paint and color, and palette and gamut.

1 Paint mixing is an activity with physical substances, so the results depend very much on the physical qualities of the substances you use.

Watercolor painters learn how to manipulate pigments mixed in a gum vehicle with water and applied to cellulose paper.

2 There are several physical attributes of paints that are important to all painters. First among these is the color appearance, described in terms of lightness, chroma (saturation) and hue or its color name around a hue circle (right). Other important attributes include the paint's tinting strength, lightfastness and, for watercolor painters, its transparency.

The three color appearance attributes should be illustrated through simple visual comparisons or demonstrations, both with paints and with a pair of prisms, not described here. Demonstrations of the other attributes are described below.

the hue circle

a hue circle describes the abstract
relationships among colors (not paints); the letters denote colors described in section 5

3 A painter's palette is the selection of paints that he will use to mix all the colors he wants in a painting. A painter's gamut is an image or map of all the possible colors that mixtures of the palette paints can make.

In paint media, the colors of the most saturated paints on the palette (and sometimes also the darkest color, such as black) cannot be duplicated by mixtures of any other paints on the palette — the mixtures will be too dull. So the pure paints are called the palette primaries because they are the most saturated colors of their kind. The palette primaries create all other colors and determine the palette's color range — the total number different colors the palette can mix.

4 In watercolors, water is used to lighten the color of paint mixtures toward the white of the paper, so white paper is also a palette "primary". A watercolor gamut is affected by the whiteness (or color) of the paper that the paints are applied to, by the surface texture of the paper, and by the tendency of the paper to hold paint on its surface rather than soak paint into its inner fibers. The largest gamut is produced by very reflective, white papers with a smooth finish that holds all the paint on the surface.

A very dark gray or black can be mixed from the highly saturated paints. A premixed dark shade is fairly popular among watercolor painters as it provides the black ready mixed with a bias toward green, blue, violet or brown.

5 The most effective palette to use for learning color mixing consists of six highly saturated paints that are evenly spaced around an idealized color circle. The traditional selection of hues is: magenta, orange, yellow, green, cyan and violet. These color labels have specific meanings for painters that do not exactly match our commonplace color names:

• magenta (M) means a bluish red that is almost red violet
• orange (O) means a reddish orange
• yellow (Y) means a pure yellow
• green (G) means a middle green
• cyan (B) means a greenish blue
• violet (V) means a reddish blue that is almost purple.

These six hues define a palette of six primary paints, the six color palette. No "color" (paint) is more important or more useful than any other; the painter's gamut (color mixing range) depends on all the paints working together as a team.

A delightfully compact and elegantly designed color tutorial based on the secondary or six color palette is available as Ordering Colors, Playing with Colors by Moritz Zwimpfer (School of Design Basel/Verlag Niggli, 2002).

6 These six paints create a matching hexagonal or six paint gamut (right). None of these paint colors can be mixed by any of the others, so all six paints are palette primaries. Any mixture of two or more palette primaries, plus water and/or black paint if necessary, creates a color that is located on or inside the gamut boundaries. The gamut therefore contains all mixable colors.

However, no paint palette can mix all visible colors, for example the colors of fluorescent paints, gems, stained glass, prism spectrums, and lights. These unmixable colors lie outside the gamut.

Palette "primaries" are the paints at the corners of the gamut that create all the possible color mixtures inside the gamut. They are not abstract or ideal colors. This is always true no matter what you use for color mixing — paints, inks, dyes or lights.

the six paint palette as a
(real) hexagonal gamut

a gamut is used to guesstimate
the result of mixing paints (not colors)

7 In a real gamut, the palette primaries are not equally spaced from each other and are not the same distance from the neutral gray center or from a pure white or black: a palette does not form a symmetrical circle. Thinking in terms of a color circle creates many false ideas about how paints mix together. Try to visualize color mixtures in terms of a real gamut, not an abstract color circle.

8 Hue is represented in the gamut by the clock face location or hue angle of the color around the gray or neutral center (N) of the gamut: yellow is approximately at 12 o'clock, green at 2, cyan at 4, blue violet at 6, magenta at 8 and orange at 10.

The hue angle created by a straight line from the neutral center through the gamut boundary shows the proportions of the two closest palette primaries that will mix the most saturated or intense version of that hue. For example, a hue line that points to 1 o'clock on the gamut is halfway between the yellow and green palette primaries, and therefore is a yellow green that can be matched by a mixture of equal parts green and yellow paint at equal tinting strength.

saturation costs in the
hexagonal gamut

saturation costs occur between any two
paints or paint mixtures, regardless of color

9 Chroma is represented in the gamut by the distance of a palette primary or paint mixture from the center toward the edge of the gamut. Paints or paint mixtures at the center of the gamut are very dull, gray, or neutral (N in the gamut diagram). Paints or mixtures close to the edge of the gamut are bright, intense, or saturated.

In all paint palettes, the palette primaries do not have equal chroma and are not an equal distance from the neutral center. This affects their color mixtures.

10 The rule of saturation costs is: the farther apart two paints are in the gamut, the duller and/or darker their mixture will be.

The mixture of any two neighboring palette primaries produces the most intense or saturated version of the hues between them; these mixtures define the gamut boundary across those hues ("intense green" in the gamut diagram). So a green mixture made with yellow and cyan ("dull green" in the gamut diagram) will be duller and/or darker than the matching hue mixture of yellow and green paints, because the yellow and green are closer together. A green mixture of yellow and violet will be even duller ("gray green") because violet is farther from yellow than cyan or green.

11 Lightness is the gamut variation in color mixtures from the darkest value (the palette black or darkest neutral mixture) to the lightest (the paper white).

Any mixture of a palette primary or color mixture with white (dilution with water) produces tints of the color.

Any mixture with a black, dark shade or dark neutral mixture produces shades of the color.

Any mixture with a neutral or gray of equal value produces tones of the color.

Lightness is not shown on the gamut because it is the most obvious color attribute, and so that the hue and chroma of the most saturated paint mixtures can be visualized clearly. However, as mixtures become lighter or darker the gamut contracts — the range of different colors grows smaller.

12 A paint or paint mixture reaches its maximum chroma or color purity at a "not black, not light" dilution, usually at a ratio of paint to water between 1:4 to 1:8. (The exact ratio of paint to water is different for different pigments and paint brands.) From that point chroma is always reduced by diluting further with white paint or water.

However, paint mixtures in all tints and tones have a different, characteristic look: more diluted paints tend to show more pigment texture, and produce a more luminous or light emanating visual effect. The painter must explore paints at all concentrations to learn how to produce these varied effects.

The hue of a paint or mixture may change as it is lightened with water or white paint. Typically, deep yellow, orange, green and blue colors appear to become more yellow in tints; deep reds and violets seem to shift toward blue, and very dark or dark shade paints, which appear to have no color, will acquire a distinct hue in tints. The hue of yellow appears to shift toward green if it is darkened with gray, black, blue or violet paint.

13 Mixtures between any two primaries form a unique sequence of colors. By practicing the skill of paint mixing using two primaries at a time, the painter learns the hue and chroma of these colors firsthand.

The hue and chroma of any mixture of two paints is estimated as the "center of gravity" or balance point of their relative quantities and tinting strengths in the mixture, along a straight line between their hue/chroma locations on the gamut.

The student should learn these color mixtures by making 15 mixing step scales between all paint pairs around the gamut (diagram at right). To prepare these scales: (1) paint the two pure paints at opposite ends of the scale, (2) mix the two paints until a color is reached that appears midway between them, and paint this mixture in the middle of the scale, (3) mix half the remaining middle color and one primary to produce a color that appears midway between them, and paint this color between their color samples, and (4) do the same for the remaining middle mixture and second primary. A finished scale (for magenta and yellow) will look like this:

This exercise asks the student to paint 75 color samples and to make and paint 45 color mixtures, which teaches effective paint mixing habits. The student should also mix the 5 step scales showing the shades, tones and tints of each palette primary (its mixtures white, black and a middle valued gray) to experience the hue shifts that occur within lightness and chroma changes only. These add another 30 scales, 90 paint samples and 54 paint mixtures to the exercise.

mixing step scales among all pairs of palette primaries

14 Each combination of two paints on any palette produces a unique range of color mixing effects as the proportions of the two paints are changed and as the mixture is diluted with water, white and/or black paint. These effects must be learned through experience by actually mixing the paints and using the mixtures in paintings. The only way to learn to paint is to make many paintings.

Mixtures will change if any substitution is made in the primary paints on the palette. Experience with the same palette primaries improves color mixing accuracy and efficiency, and skill in producing subtle color variations, which is why painters prefer to work with the same palette across many different paintings.

15 In preparing the mixing step scales, including the tint scales, the student discovers that some palette primaries assert themselves in a paint mixture more than others; more of the weaker paint is required to produce a color that appears midway between the two paints. This strength or dominance in mixtures is the tinting strength of the paint.

Tinting strength is measured in two ways (diagram at right): (1) in the intensity of the tint produced by a 1:10 mixture of the paint with titanium white paint or water, or (2) by the relative hue of a mixture of two paints in equal physical proportions. In the example (at right, top), the tinting strength of the magenta paint B is higher than paint A, because it produces a darker tint in an equal proportional mixture with white paint. In the example (at right, bottom), the relative tinting strength of the magenta paint is greater (or the relative tinting strength of the yellow paint is less) in B compared to A, because the mixed hue is closer to magenta than to yellow.

If paint quantities or relative tinting strengths are unequal, the mixed hue is closer to the paint color that contributes more in quantity and/or tinting strength to the mixture.

The student should pay attention to the relative tinting strength of all paints on his palette, as this minimizes the amount of back and forth addition of one paint, then another, necessary to get the desired color.

two measures of paint tinting strength

(top) 10:1 mixtures of titanium white paint and colored paint; (bottom) 1:1 mixtures of two colored paints

16 The transparency of a paint is fundamentally determined by the dilution of the paint in water: the greater the proportion of water to paint in a mixture, the more transparent the finished color will be. Transparency often appears greater for pigments with higher tinting strength, because the paint produces a more powerful color at higher dilution. (To compensate, most manufacturers "predilute" these dominant pigments with a larger quantity of vehicle or extenders.)

If all paints are diluted by the same amount, then transparency depends primarily on the particle size of the pigment and its ability to refract light.

A completely transparent paint will seem to disappear if painted on a black surface. A completely opaque paint, which is high in hiding power, will seem to cover completely a pattern of black and white squares or lines on paper. These are two different paint attributes, but watercolorists are usually more concerned to avoid paints with high opacity or hiding power.

Some painters test paint transparency by painting overlapping stripes of paint in sequence, so that each paint is painted over itself and under and over all other paints; in this test the more opaque paint will (1) change color less when painted over itself, and (2) dominate any color it is painted over. In the example at right, the magenta and yellow stripes are painted in numerical order, and the yellow paint is less transparent (more opaque) than the magenta.

This method is inconclusive, as dark paints or strongly tinting paints can also seem to "hide" the paints underneath them. The more accurate test is to apply the paint over an area of indelible black lines: the difference in appearance between the painted and unpainted lines is a direct, accurate measure of paint opacity or hiding.

two measures of
paint transparency or hiding power

17 Adequate paint lightfastness is essential to the permanency of watercolor paintings. Students should learn the basic logic and procedures of lightfastness tests. These expose standard samples of paint to prolonged sunlight or artificial light exposure, while masking part of the sample from light; after an appropriate exposure period, there is a visible difference between the exposed and masked paint areas in impermanent or fugitive paints. The student should be taught to avoid fugitive or impermanent paints — which includes all 19th century organic pigments (alizarin crimson, rose madder, carmine lake) and many convenience (premixed) greens and purples. All artists should periodically test their paints, inks or colored pencils to confirm manufacturer quality standards.

18 Once the painter understands the relative tinting strength and transparency among the palette primaries, and the relative changes in paint hue, lightness, chroma and lightfastness in mixtures with other paints and/or water, he intuitively understands the basic mixing method sufficient to mix any color from the palette primaries.

The painter first identifies the approximate gamut location of the target color or color to be mixed. He then selects the paints necessary to mix the target color — two, if the color lies on a mixing line between two palette primaries, or three, if the color is contained by a triangle defined by three primaries. In the case of three paints, the painter draws a line from one primary through the target color to the gamut boundary opposite to determine a hue target. He then mixes the two primaries on that side to match the hue target. Then, he adds the third primary to draw the mixture back to the target color. Finally, he adds water or a fourth paint, as necessary, to make final adjustments to the lightness and chroma.

the basic mixing method

19 There are several specific rules for changes in paint lightness, lightfastness and tinting strength that apply to all paints and all paint mixtures:

(a) The lightness of an equal mixture of two paints is always closer to the darker paint in the mixture.

(b) The tinting strength of a mixture is the average tinting strength of the paints in the mixture.

(d) Lightening a paint by mixture with white paint or water significantly reduces the lightfastness of marginally lightfast paints; mixture with other paints, including black paint, has a weaker but still noticeable effect on lightfastness.

(e) The lightfastness of a mixture is usually no greater than the lightfastness of the least permanent paint in the mixture.

(f) Many bluish red paints, and mixtures of a warm and a cool paint — especially green and violet mixtures — are the most common source of lightfastness problems.

20 As the student makes more paintings he can be introduced to the other paint physical attributes important to watercolor painters, which should be explained in terms of the basic ingredients in watercolor paints:

• staining, or resistance to removal by scrubbing or blotting, is caused by small pigment particle size, low proportion of gum binder in the vehicle, added dispersants or humectants, and absorbent or lightly sized paper.

• lifting, or the tendency of the paint to redissolve when a new layer of paint is applied over it, is due to large particle size and a high proportion of gum arabic in the vehicle

• specific gravity, or the weight of pigment in water, is revealed by how quickly the paint sinks to the bottom of a container when mixed with pure water or how quickly the paint separates when mixed with a second paint (for example, a phthalo with a cadmium or cobalt pigment)

• granulation, or the visible grainy texture of the paint, is due to large paint particle size and/or increased dispersant in the paint vehicle

• flocculation, or the appearance of clumping or scaling in the dried paint, is due to electrostatic attraction among dissolved pigment particles or diluted paint that is applied in a juicy brushstroke

• dispersion, or the tendency of the paint to expand rapidly when applied to wet paper, due to small particle size and dispersant in the paint

• the tendency of the paint to form a backrun when rewetted after it has partially dried, is increased by small particle size or added dispersant, when water or paint are added to paper that has dried to a satin wetness

• the tendency of the paint to bronze when applied as a thick mixture, caused by a high proportion of binder to pigment and a low proportion of plasticizer to binder in the paint.

21 Experience with any palette will reveal fundamental quirks in the palette mixing capabilities (diagram at right); these arise from peculiarities in our color vision and in the color purity of available pigments, and they appear across all subtractive mixture media (paints, inks, dyes, filters):

(a) Dull orange or yellow mixtures, or mixtures of orange+black or yellow+black, produce qualitatively new unsaturated colors commonly called browns, ochres or green golds; similar colors do not appear in green, blue or violet areas of the gamut.

(b) Mixtures horizontally across the gamut, from cyan to magenta or from green to orange, produce generally darker or duller colors than mixtures vertically across the gamut, from magenta to yellow or orange to violet.

(c) Some paint combinations, especially orange with cyan and magenta with green, can in the right proportions produce mixtures visually indistinguishable from pure gray or black; these are true complementary colors.

(d) Magenta+green (or red+blue green) mixtures are especially dark and often can substitute for a black paint on the palette.

variation in primary mixtures and
in gamut mapping to light

22 A paint gamut is only a rough guide to paint mixtures: it provides a compass to guide your mixing improvisation of colors. For example, the mixing lines in most gamuts are not always straight but can be curved, especially in green or near neutral mixtures. The painter uses the gamut as a visual aid to decide how to make new color mixtures with the six color palette, and to guesstimate what the mixture of two or three paints will look like.

23 Painting skill depends on many things, but the two most important are patience and practice. Only long experience with mixing paints lets a painter anticipate color mixtures; only the experience of making many paintings lets the painter use color confidently and with feeling. Make as many paintings as you can, and let yourself enjoy the process of painting, and your progress will surprise you!