Original poster Aponi/Miki
WARM VS COOL COLORS IN THE COLOR CIRCLE
Whatever your views on this
dichotomy, it's common practice and often useful to describe a color as warmer
or cooler in comparison with another color. This simply indicates whether the
color is closer to red orange (warmer) or to cyan (cooler) than the comparison
color - or, closer to yellow or blue violet, if you prefer the alternative
yellow/blue violet contrast. Thus, red is a warmer color than magenta, because
red is closer to red orange, even though both are warm colors in comparison to
blue violet. These relative comparisons are most often applied to analogous
colors (of similar hue) - a "warm blue" (compared to other blues) or
a "cool red" (compared to other reds). Thus: • quinacridone red
(PR209) is a cool red and naphthol scarlet (PR188) a warm red • hansa yellow
deep (PY65) is a warm yellow and hansa yellow light (PY3) a cool yellow •
chromium oxide (PG17) is a warm green and viridian (PG18) a cool green • cobalt
blue (PB29) is a warm blue and cobalt teal blue (PG50) a cool blue • cobalt
violet (PV14) is a warm violet and ultramarine violet (PV15) a cool violet.
Occasionally a wider comparison is made across two or more hues, but it is
still decided by the relative distance in a color wheel between the two colors
and the warmest/coolest hue. @#%+$$'s green is warm (closer to red orange or
yellow) when compared with viridian, but is cool (farther from red orange or
yellow) when compared with green gold. What about dull (near neutral) colors?
If all colors must be either warm or cool, the common 19th century practice was
to assign "gray" to the cool hues (as in a gray or overcast day).
This is primarily because most grays or dark neutral mixtures used in painting,
including payne's gray, indigo and neutral tint, actually have a distinct blue
or green tint. If colors are judged in relative terms, then a grayed color is
either warm or cool using the same "distance in a color wheel"
comparison as before. That is, a grayed blue green is warmer than a saturated
blue green, because the gray is closer to red orange across the center of the
hue circle. In paint mixing terms, some red orange has been mixed with the blue
green in order to gray it, and this red orange appears as a warming of the
color. In general, all dull cool colors are warmer than their saturation hue
match, and all dull warm colors are cooler than their saturated hue match.
Thus, burnt sienna is cooler than cadmium scarlet, because it is less saturated
(closer to gray). The same principle applies if you are using the alternative
yellow/blue violet contrast: ultramarine blue is made grayer (and warmer) by
the addition of some burnt sienna, and burnt sienna is made cooler by adding
some cobalt blue.