Traditionally, painters use a color wheel whose primary colors are red, yellow and blue. A very limited palette of red, yellow, blue and white might include just permanent red, hanza yellow medium, ultramarine blue and titanium white. You will find, however, that, because paints are not perfect “primary” colors, you need a limited palette of at least two reds, two yellows, and two blues (one of each hue veering towards the “warm” and other towards the “cool” spectrum. Alternately, you could build your palette around the primary and secondary hues: red, yellow and blue would be the primary and orange, green and violet the secondary colors.
The history of the color wheel is interesting. In the mid-eighteenth century, scientist Isaac Newton’s experiments with prisms resulted in the theory that red, yellow and blue were the primary colors, although color theory no longer supports the concept that all other colors can be mixed from these primaries.
At the time of the Impressionists, some innovative theory on color was being developed. A Mr. Chevreul was establishing a color wheel and Mr. Rood had just published a work on the theory of color in 1881. The Impressionists (and Neo-Impressionists) adopted these theories and arranged their palettes according to the chromatic tables furnished by the physicists. "Following the theory that light, broken up in a prism, gives off seven colors, they adopted these seven colors on their palettes." They excluded black. Duranty, a prominent writer of the time, felt that they were handicapped by this. Unlike the "true" Impressionists, Mary Cassatt, Edgar Degas, and Edouard Manet did not exclude black, but used it richly. (This last information was extracted from Mary Cassatt 1844-1926, National Gallery of Art, 1970 Exhibition Catalogue)