This paper deals with processes which operate when pigments are combined. Usually it is assumed that one may learn of these processes only by trial and error and that information acquired in this way cannot be imparted to others. From experience as a painter and decorator the writer has long believed otherwise; that is, that these processes are simple enough so that, given a proper method, useful information about them could be organized and presented in a form understandable to any interested person. With this in mind a simple diagram was devised to show general mixture-relationships among red, yellow, and blue pigments and their combinations. Though this was useful to a degree, its limitations were evident, since it did not deal concretely with most pigments in common use. By trial and error, points indicating a selection of pigments were incorporated into the diagram, with the objective that color-mixture relationships among the pigments should be expressed in terms of linear relationships among the points. The advantages of such an arrangement were at once apparent. Using this as a point of departure and drawing from the experience of people inquiring into similar processes operating when colored lights are combined, a new color system was built, consisting of devices and conventions designed to supplement and facilitate use of information so presented. To what degree the pigment positions had been so arranged as to secure the nearest-possible approach to linear color-mixture relations remained for a time unknown. Meanwhile doubt was expressed that it is possible to arrange them so as to provide useful approximations of the relationships involved. Then a new experimental technique was devised. This led to correction of errors in locating the pigment positions and produced evidence that information about color-mixture relationships among pigments can be summarized very well in diagramatic form. Some features of the color system mentioned are noted. The experiments are described and data presented for review.
EDWARD FRIEL, "New Pigment-Mixture Diagram and Color System," J. Opt. Soc. Am. 49, 1159-1168 (1959)