nse to color and to the manipulation of colors in painting?
What Are the Warmest (Coolest) Hues? As Hayter's diagram indicates, the most common choice for the warmest hue is usually an orange or red orange with a CIELAB hue angle around 40 to 45. This includes red orange paints such as perinone orange (PO43) or pyrrole orange (PO73), or slightly darker orange red paints such as naphthol scarlet (PR188), pyrrole scarlet (PR255), cadmium scarlet (PR108). The principal criterion here is that these scarlets are among the most intense pigments available. However burnt sienna (PBr7) is the best choice for a dull red orange among earth orange paints.
Some artists prefer orange paints such as cadmium orange (PO20) or benzimida orange (PO62) with a CIELAB hue angle around 50 to 55. Orange hues are lighter valued, very intense and balanced between yellow and red.
The coolest color is whatever provides the complementary contrast to the warmest hue already selected colors opposite red orange or orange in a visual hue circle, as found in the Munsell Color System or in CIECAM. These indicate that the coolest hue is a blue or green blue with a CIELAB hue angle around 220 to 235. There are few pigments in this region of the color wheel, but they include manganese blue (PB33), phthalocyanine cyan (PB17) and cerulean blue (green shade, PB35). Pigments on the fringes include phthalocyanine blue (green shade, PB15) and cobalt teal blue (PG50).
But artistic practice has not been unanimous. An important and fairly common alternative is to choose yellow as the warmest hue. This usually means choosing an intense orange yellow paint, such as hansa yellow deep (PY65), nickel dioxine yellow (PY153) or nickel azomethine yellow (PY150), a dull earth yellow paint such as yellow ochre, gold ochre or raw sienna (PY43), or an intense yellow paint such as hansa yellow (PY97) or cadmium yellow (PY35) as the warmest pigment. Then a violet blue paint (ultramarine blue, PB29) or a blue paint (cobalt blue, PB28 or iron blue, PB27) are usually effective as the cool complement. These choices define a yellow/blue contrast as an alternative axis of warm/cool effects. It makes all hues containing yellow (from orange red through yellow green) warm colors, and all hues containing blue (from blue violet through blue green) cool colors.
This warm/cool choice is a proxy for the long and short wavelength analysis optimal colors identified in my synthesis of surface colors. Optimal orange is the color produced by the sum of all long wavelength light (above 570 nm), and is closely matched by nickel dioxine yellow (PY153) or isoindolinone yellow (PY110). Optimal blue is the color produced by the sum of all short wavelength light (below 485 nm), and it is closely matched by ultramarine blue (PB29).
This approach is especially suitable when the artist intends to use yellow as the symbol of light. This matches our experience of color variations in three ways. First, the hue contrast is aligned with the largest value contrast the lightest saturated hues are yellow, and the darkest hues are blue violet. Second, as explained below, the major visual axis that captures chromaticity variations in natural light (landscape light) extends from yellow to blue. Third, most colors shift toward yellow as the luminance on or through them becomes more intense: blue violets become blue, blues become blue green, greens become yellow green, oranges become deep yellow, and "spectrum" reds become orange. (Purples shift either toward red or toward blue, depending on the balance of the color.) The effects of reflected, filtered or shadowed light transition in the opposite direction, from yellow to red or green blue to blue. Thus, layers of translucent yellow material redden as they become thicker, cyan tropical shallows darken to blue as waters get deeper.
J.M.W. Turner provides some classic examples of this approach. In many of his paintings, the lightness of colors is closely aligned with the color temperature (yellow is the lightest color, blue violet or gray the darkest), so lightness and warm