Setting your palette means taking some time before painting to premix the range of colors you will paint from. It allows you to separate the tasks of coloring from actual painting. A typical process may go as follows:
1. Identify major colors in composition and premix matching ranges of color with a palette knife. Save these to the side of palette, or a different palette altogether.
2. Double-check premixes by comparing with one another on palette. Hue, chroma, and especially value relationships should be correct before painting
3. Paint from the premixed piles with minor adjustments
Value Strings
Value strings are premixed colors that move through a range of values. Often they are mixed to hold the same hue and chroma, but vary only in value.
There is evidence that many 19th century realists used value strings. Their palettes were organized according to value first, and hue and chroma second. This is because as light rakes across form, the largest changes are value changes. Changes in hue and chroma are smaller –often much smaller than we first think. Flesh tones are an example of this.
Painting Flesh Tones
Human flesh tones of all races fall within a very narrow range of hue and chroma. Even with specular highlights and a variety of different lighting, human flesh falls within the neutralized yellow-red range, sometimes slightly tipping to a neutralized blue-green.
Using high-chroma colors to paint within such a narrow range is inefficient and labor intensive. It will also prone you to making color errors due to your repeated need to neutralize high chroma colors back down to the actual usable gamut. Preparing a set palette of premixed colors defines the limits you will paint within and affords maximum control.
Modeling with One String
Often you can describe the effects of light falling across form with just one range of values. The range is constructed so that it records variations in hue and chroma at each value step. Start with the darks and mix to match the hue and chroma you see. Then save the mixture. Move toward the lights, mixing to match the hue and chroma of each value step. Isolate colors in the subject and compare your mixtures to double check yourself.
When you have finished mixing the highest value step, you will have one value string that can be used to model the entire form throughout the subject. If the subject contains too many hue and chroma variations within each value step, then you will need to add additional strings.
Avoiding Exaggeration
When painting larger subjects like portraits or figures, there may be too many hue and chroma shifts within each value step to describe with only one string. Therefore you will need additional hues and chromas.
It is easy to exaggerate subtle hue and chroma shifts and push them wider than they actually are. This is especially true in open palette systems, where you are free to add more and more chroma from piles of unmixed pigments. Your tendency will be to push hue variations wider and wider as optical illusions distort your color sense. Eventually you may push them beyond the gamut of flesh entirely.
Predetermine Hue and Chroma Limits
To prevent exaggeration you must determine the hue and chroma limits, or gamut, that you actually see. Then you must premix colors at these limits and paint only from them. In addition to your neutral grays, you will need at least two additional value strings. These should bracket the widest variation of hue and chroma you can identify.
In human flesh of all races, there will be a small range of different hues, as forehead differs from nose, etc. The range will be small and remain fully within the neutral-yellow-red family. Remember that even in extreme light, the hue deviation from one area to another will be smaller than your eye tells you it is. Double check yourself by isolating the color in question and mixing color until you match it.
Color Matching
An even more precise method is to hold up a Munsell color chip to exactly identify the hue and chroma in question, then note the results. In the Munsell system, 5R at the 6th chroma, and 10 YR at the 6th chroma are the basic limits of flesh of all races, under average lighting. Additional hues and chromas will be the exception, rather than the rule.
If you do not own Munsell color chips, then mix the hue limits and sight them against the model. Start by selecting a middle value within the halftones of your model. Highest chromas are located there. Then mix one color at the yellow limit you can see, and the other at the red limit you can see. Make sure values are the same between the two colors. Compare your mixtures to the model until you have reduced the chroma enough.
The idea is for these two colors to bracket the widest hue and chroma variations evident in the model. Mixing will then take place between these two hues plus neutral gray.
Premixing Values
Finally, mix a range of values for each of the above two mixtures, maintaining the same hue and chroma at each step. You can mix as many as nine steps, however, five may be more manageable at first. Each value step should remain consistent between all color strings, including your range of neutral gray.
You can approximate all of this by eye, and then preserve color swatches for future mixing. However, this will require a great deal of trial and error.
Munsell Value Strings
The Munsell system provides a map of dark to light values at all hues and chromas possible in opaque media. Each value string preserves the hue and chroma throughout all nine value steps.
Premixing paint strings to match Munsell values easily mitigates the chroma and hue distortion of white paint. The Munsell system has already adjusted the ratio of pigments within each value step to exactly preserve the hue and chroma throughout the range. All you have to do is mix color to match the chips.
Using the Munsell system to create value strings exceeds prepared palettes of the past. The control over hue, value and chroma provided by Munsell is unprecedented in the history of painting.
Painting with Value Strings
During painting, adjust value by moving up or down the value strings. Adjust hue and chroma by simply mixing across all three strings at the same value step. It is that simple.