These are not problems unique to the "primary" triad palette. They are four fundamental palette limitations that affect all palettes in all painting or drawing media:

• limited value range

• limited chroma

• pigment monotony, and

• color mixing inconvenience

Chuck Long's palette choices illustrate the common solutions that artists find for these limitations. Long paints in several genres (he is primarily a landscape and aviation painter), yet he solves the palette problems with ten paints.

For comparison, here again is the "primary" triad palette scheme (below left), which in Long's palette consists of cadmium yellow (PY35), alizarin crimson and phthalocyanine blue GS (PB15), circled in the palette scheme (below left). What changes has Long made to this palette, and why?

solving the four fundamental palette limitations of
the "primary" triad palette

1. limited value range. As value structure is the dominant information in an image, a large value range is almost always desirable. Reasonably dark black mixtures are possible with the "primary"triad palette, if you use a very dark blue or cyan paint; but they are tedious and inconvenient to mix and they do not produce the maximum value range (depth of dark mixtures) possible in watercolor paints.

Long solves this problem by adding a cool, near neutral paint (the convenience mixture payne's gray, which is just the marketing name for a group of modern paints (including indigo and neutral tint) made with carbon black (PBk6 or PBk7) tinted with phthalo blue. These paints provide a cool black that is useful as a shadow color and, strongly diluted, can render cool, veiled skies or water.

This is a fundamental change, as it joins the "primary" triad palette with the value design palette to create a balance between the chroma range and value range. This remedy is also used in CYMK process printing: a fourth printing plate inked with black is used to create deep blacks and near grays. (Oil painters additionally have to add a white paint to their palette, to increase the value range at the high end.)

2.  limited chroma. Adding a "black" paint essentially expands the gamut of the palette along the value dimension; Long makes three more additions intended to increase the maximum chroma across the orange, violet and green hues where the "primary" palette saturation costs are most extreme.

First is the convenience mixture sap green (listed under PG7), which enhances the chroma and darkness, and greatly reduces the mixing hassle, of green colors. Second is dioxazine violet (PV23) to brighten the notoriously dull violets of the "primary" triad (especially when these are mixed with alizarin crimson). This paint is also the mixing complement to most yellow greens, for example to produce the forest darks in the demonstration painting. And last is cadmium scarlet (PR108), to goose up the chroma of mixed reds, oranges and deep yellows. These additions yield almost all the chroma range that is possible with a palette of six paints.

3. pigment monotony. Most painters love pigments for themselves, as magically colored substances. But the typical primary triad palette consists of three synthetic organic pigments with very similar transparency, texture, staining and handling attributes. Most painters prefer greater variety in their paints.

Although pigment variety has become much less popular in contemporary watercolor brands, all include a selection of blue pigments that are the traditional reserve of pigment texture. Long's next paint additions, cerulean blue (PB35) and ultramarine blue (PB29), do not expand the chroma or value range of the gamut by very much, if at all. Their main attraction is their fleecy or grainy textures, which emerges in all the washes and color mixtures made with them. Long's delight in these texture possibilities appears in his poetic sky.

Other pigment attributes — transparency, staining, tinting strength and lightfastness in particular — are also important to many painters, and most professional palettes include some paints chosen for their specific pigment attributes separate from their inherent color or impact on the mixing gamut.

In that regard, the glaring defect in Long's palette is his choice of alizarin crimson (PR83), a fugitive pigment unsuitable for professional artistic work. It should be replaced with something — anything! — more permanent, such as quinacridone carmine (PR N/A), perylene maroon (PR179), quinacridone magenta (PR122 or PR202) or quinacridone rose (PV19), among many alternatives now available.

4. mixing inconvenience. Finally, if a big gamut was his goal, why didn't Long use a pure pigment green paint, such as phthalo green YS (PG36) or viridian (PG18)? The most likely reason is that natural foliage greens look best in the gallery when painted duller than they appear in the field, so an intense, pure green pigment such as phthalocyanine green would create more mixing work — yellow must be added to shift it toward a foliage yellow green color, then scarlet, crimson or purple must be added to dull the chroma. A premixed sap green (or similar convenience greens such as hooker's green, permanent green or olive green) provides a generic dark, dull green that is easily modified by the addition of any other paint on the palette. It does not need to be shifted very far to get a convincing variety of green colors.

For similar reasons, Long adds burnt sienna (PBr7) as a warm "home base" for all manner of woods, earths, rocks, portrait complexions, dried leaves and grasses and as a reliable and gentle neutralizing paint for the sap green. Again, the key is that the convenience paint creates an interesting and handy range of colors when tinted by any other paint on the palette; and a touch of the convenience paint can mute or shift the other paints in useful ways. For example, the granulating, knotty and dark mixtures of burnt sienna and ultramarine blue can be especially lyrical.

Overall, these choices represent a significant attitude change toward the "primary" triad palette. "Color theorists" see paints as "colors", as abstractions without body or soul, which means one red paint is more or less just like any other. To "color theorists", palettes have a limited gamut only because the paints are impure, and pigment monotony or mixing inconvenience simply don't matter.

Long's palette shows that he sees painting as a craft activity, in which the convenience of paints for mixing color is the same as the convenience of using the right tool for the right job. He also sees paints as materials rather than "colors" — each paint unique for its particle size, texture, staining and transparency, each capable of imparting a distinctive texture, flow, complexity and random variation to the surface of the painting.