Natural light contains all the colors of the stectrum. By breaking light down into its component parts, or spectral colors, it is possible to combine and mix the individual colors to form new ones. Additive color is the process of mixing colored light. The most common application of this can be found in theater lighting. For example, a red light overlapping a green light produces a yellow light. Colored pigments, however, behave very differently than colored light when combined or mixed. The primary colors of light are red, green, and blue; the primary colors of pigments are red, yellow, and blue. When all three primary colors of light are combined, they form white light, and, when two colors of light are added together they always produce a color of lighter value.
The principles of additive color are most critical in theater or other dramatic lighting. For the purposes of interior color design, it is important to understand the effect of artificial lighting on the perception of color. For example, incandescent light brings out the warm colors of an interior while fluorescent light emphasizes the cool colors.
Subtractive color is the result of mixing pigments, dyes, or other colorants. The apparent color of a surface is based on what part of the visible spectrum of light is absorbed versus what portion is reflected back to the viewer. Since the main concern is the color of interior finishes, an d not lighting, the focus will be on substractive color, rather then additive color.
The primary subtractive color are red, yellow, and blue. These are called primary colors because all other colors are derived from some combination of these three. When all three primary colors are combined in equal amounts the resulting color is a deep, blackish brown. Note that the primary colors are spaced exactly equidistant from one another on the color wheel. Midway between each primary color is what is called a secondary color.
When two adjacent primary colors are mixed together they form the secondary color found between them on the color wheel. For example, yellow and blue paint mixed together makes green. The other secondary colors are orange and purple. When adjacent primary and secondary colors are mixed, they form tertiary colors. Between each of the six primary and secondary colors are the tertiary colors i.e. red-orange, orange-yellow, yellow-green, green-blue, blue-purple, and purple-red.
When a very consistent, fine pattern of two distinct colors is viewed from a slight distance, the eye tends to mix the colors optically and derive a third color. This is called partitive color.
A commonly used example of partitive color is the post impressionist painting technique of pointillism, where small dots or points of different colors are placed on the canvas to create an extremely rich, vibrant color. In architectural color, the greatest richness and depth is achieved with partitive color mixing, such as in glazing or in the stippling techniques of decorative painting. The subtle, multicolor effects of stone or wood are examples of partitive color used in natural materials. When granite is viewed very closely, numerous shades of gray are apparent, yet when viewed from a distance, all the little specks of color blend to form a complex, rich gray which would be unachievable with a uniformly colored surface.
