This section is from the book "Clothing For Women: Selection, Design, Construction", by Laura I. Baldt. Also available from Amazon: Clothing For Women: Selection, Design, Construction.
Where there is light there is color. Color is refracted light, that is, light broken up into its component parts. Every ray of light is composed of a group of perfectly balanced color waves or vibrations, which are conveyed through the eye to the brain as color sensations. This may be demonstrated by letting a ray of sunlight pass through a glass prism and fall on a white surface; the result is a band of prismatic colors, blending almost imperceptibly into each other - forming a rainbow. This is also called the spectrum, the principal colors of which are red, yellow, green, blue and purple, with their intermediate gradations, in the order given. The sequence of the colors of the spectrum suggests a circle (Fig. 28). By using a second prism placed in a position to catch the refracted rays of light from the first prism the spectral colors will revert to white light. This is nature's clue to color study.
Fundamental or primary color sensations of the spectrum are green, red and purple. The term "primary color" (as distinguished from the mental "color sensation") is often used to designate the three principal pigments, red, yellow and blue.
By comparing the colors in the spectrum we find that they differ in three ways. (Study a good prismatic color chart or a prism.)
1. Hue. - The name of the color. The quality which distinguishes red, yellow, blue, etc., from each other, irrespective of other differences. The hue of any reddish color is "red," and its redness is its hue quality; so, the hue of blue distinguishes all blue colors. This is a difference of warmth and coolness and red and yellow are called warm colors and blue a cold color.
2. Value. - The quality which distinguishes the relative amount of white and black in a color, irrespective of other differences. This is a difference of light and dark.
3. Chroma. - The quality which distinguishes the degree of intensity and brilliancy of a color, as compared with grayness. This is a difference of strength and weakness.
Pigments are any material means used to give rise to color sensations, such as paints, dyes, inks, etc. All pigments are more or less chemically impure, and therefore cannot perfectly represent spectral color. If tested by combining with each other the best pigments in spectral colors, the result will be gray and not white (compare with the experiment of the prisms). Material color is dependent upon the reflecting and absorbing qualities of the surface on which the rays of light fall.
Principal or " primary" pigments are red, yellow and blue. These colors cannot be obtained by the admixture of any other color pigments; but by various combinations with one another they produce all the other hues.
Secondary color pigments are orange, green and violet. These are hues made by mixing two principal colors. Orange is made of red and yellow, green of blue and yellow, and violet of blue and red.
Tertiary color pigments are citron, russet and olive. These colors are composed of all three of the principal pigments. Red predominates in russet, yellow in citron, and blue in olive.
Fig. 28. - Color gradations.