ADDITIVE COMPLEMENTARY HUES Wave lengths, fa Colors • 0.6562 0.4921 Yellow. Genuine ultramarine.
.6077 .4897 Green-yellow,Artificial ultramarine .5853 .4854 Gamboge. Cobalt blue.
.5739 .4821 Red, Green-blue.
.5671 .4645 Orange, Cyan blue.
.5644 .4618 Green, Purple.
.5636 .4330 • The names do not correspond to the wave lengths at the left.
Subtractive Combinations.— When two pig ments are mixed each subtracts from white light those elements it cannot reflect. The re sultant hue is therefore never identical with the corresponding additive mixture and is usually entirely different. It was known to antiquity that any color may be fairly matched in hue although not in purity by proper mixtures of yellow, blue, red. These are the pigment pri maries; to them white and black must be added to lighten or darken the hues to be produced. The production of all colors by combinations of the subtractive primaries is beautifully illus trated in the three-color process of printing in ink reasonably faithfully copies of paintings (see illustrations accompanying the article, PaocEss). A mixture of yellow, blue and red in about equal intensities gives the effect of black because they absorb practically all the constituents of white light. If this black is spread thinly as a tint it becomes gray. In gen eral, mixtures of pigments tend toward black ness on account of the absorption of color and thus of light.
Pigment primaries have complementaries; thus red and green, purple and yellow, blue and orange are complements and produce black or gray according to the density of the mixture. This gray is to be regarded as a tint of black, that of additive complements as a shade of white; the difference between the grays is of the utmost importance and is by no means a verbal quibble. A small amount of a color added to its complement dulls or grays the lat ter; such grayed hues are among our most beautiful colors and are used with wonderful effect, for instance in textile fabrics and pottery.
Unusually handsome charts illustrating pigment mixtures have been prepared by commercial firms of Boston and New York.
Contrast and The effect which two colors have in modifying each other's hue when they are placed in juxtaposition has been determined with reasonable certainty. It can be studied by putting colored strips of paper next to each other or by placing a small piece on a larger one. The general result of such experi ments is that each color becomes tinged with the complement of the other, or rather is moved nearer the complement. The diagram above was invented by Rood for predicting these changes. Diametrically opposite colors are physiologically complementary. If yellow and red are placed side by side the hue of each shifts around the circle toward the complement of the other, i.e., yellow becomes greenish, red becomes more violet or less red. In the case of red and blue, the red becomes tinged with orange and the blue looks greenish. Complements intensify each other. Whether or not these effects are agreeable depends on idiosyncrasy and circum stance. Red makes yellow look greenish; this may be pleasant or not — or neither—in; say, a wallpaper design. But a sallow-complexioned woman does not wear a red dress unless she wants to look bilious; green clothing would make her look ruddier unless some of the green were reflected to her face, in which case red would have been better. The question is not quite as simple as Rood's circle, for the in fluence of the complement is not evident when two equal areas are separated by any third color; furthermore, a small area has no notice able effect on a much larger one. Chevreul, Rood, Church, Bruecke and others have found from examinations of paintings, ornaments, etc., of generally accepted beauty that the following pairs and triads are considered to be harmoni ous and pleasing.
Good pairs : red, blue; red, blue —green; orange, green — blue; yellow, violet; yellow, black.