418 ENERGY MAY BE PROPAGATED BY VIBRATIONS Colors Are Used by Artists to Achieve Desired Effects in Accordance with Definitely Established Rules. In painting a picture, selecting clothing, or decorating a home, one should follow the example set by nature. In nature brilliant hues are never present except in touches such as contributed by occasional flowers. Colors in nature harmonize with each other because they are mixed in varying proportions and thus prevent sharp contrasts. Nature employs green in large masses in the spring, but these greens are of many values and vary from yellow-greens to blue-greens. As other colors develop, these greens become darker and grayer and Yellow Yellow Orange Yellow Green Orange Green Red Orange Blue Green Red Red Violet Violet Blue Violet Fig. 185. The color circle. Place an equilateral triangle anywhere on the color circle to obtain colors which will harmonize with each other. When using pigments, the colors at opposite positions on the color circle are complementary colors. gradually change to browns until in the fall the orange, red, and yellow colors of the flowers and colored leaves blend in with the browns in the background. Red is never found in masses in nature along with green masses but only in touches on butterflies, wings of birds, flowers, and fall leaves. When one rotates an equilateral triangle within a color circle, the points of the triangle will indicate the colors which will harmonize with each other. When using pigments, the directly opposite colors on the standard color circle are complementary. Red, yellow, and blue are primary colors, while orange, green, and violet are secondary colors — they are called secondary because they
COLORS ARE PORTIONS OF VISIBLE SPECTRUM 419 consist of mixtures of two primary colors. Tertiary colors are those made by mixing a primary color with a secondary color. Colors produced by mixture are more likely to be pleasing than pure colors used next to each other, which may produce too sharp a contrast. Expressed in another way, mixed colors are likely to be more subtle. A general rule when using any primary color is to use with it the colors on either side of its opposite to produce a softer effect; for example, good harmonies might be produced by using yellow, orange, and red-orange; the complementary colors produced by interference using polarizing screens always harmonize. In advertising, primary colors are used in large amounts next to each other in order to obtain attention. If you want to attract the attention of everyone who sees you, try wearing a yellow hat, with red pants or skirt, and a green coat. There is a symbolism in color usage that is due in part to association and in part to sensation. Red lights signify danger and are associated with stimulation and excitement. Orange and brown are associated with warmth. Yellow is light, while blue is thought of as a cold color. Warm colors are said to be advancing while cool colors are receding; for example, in a landscape the foreground iswarm, and the background is cool. Red, orange, and yellow are advancing colors, while violet, blue, and green are receding colors. Weight is indicated by dark values, while light values suggest less weight. The smaller the area the brighter the color is a statement of the law of areas in colors. STUDY QUESTIONS 1. Describe two methods of producing the spectrum. 2. What is meant by dififraction of light? 3. Why do prisms refract light? 4. Explain how the eye sees different colors. 5. What is meant by complementary colors? 6. Why does a red light carry better than a white light in a misty atmosphere? 7. What is the source of color in an object? 8. Why does the eye see green when white light is viewed after looking at red light for a short period of time? 9. How do pigments destroy color? 10. Discuss the causes of the color of the sky and clouds. 11. Explain rainbows. How is a secondary rainbow produced? Do you think that it would be possible to produce a tertiary rainbow, and if so, how? 12. Explain the formation of halos. 13. How are colors of soap bubbles produced? 14. Although kerosene is a colorless liquid, a trace of it on the surface of a pool of water will give a variety of colors. How are these colors produced?