Mixed pigment colours, as opposed to single pigment colours, are those acrylic, water, gouache, glaze and oil colours consisting of several pigments, i. e. Magenta (PR 122 / PW 6), or Titanium Yellow (PY 53 / PY 155 / PW 6). When mixing and glazing with mixed pigment colours, the number of pigments involved adds up to such an extent that undesirable interactions are practically unavoidable. The pigments contained in a convenience mixture may or may not be listed on the tube or tin, but what remains unclear in either case is the proportion by weight a certain pigment has in the mixture and in which direction the hue will cast as the mixture is glazed over or mixed with another colour. Herein lies great potential for time-consuming and expensive painting disasters.
The Soviet infantryman pictured on the right was glazed with the mixed pigment colour Lukas Studio 311 »Burnt Umber« which developed an unanticipated reddish cast. To avoid frustrating surprises, it is better to mix and glaze with single pigment colours; the alternative is to keep meticulous records of how a certain mixed pigment colour interacts with other paints on the palette.