Artist 
Writer Bias
Most primary pigments (reds, yellows and blues) are not pure primary hues, they lean towards another hue. This hue is called its bias. For example, the bias of the red color Alizarin Crimson is blue, since Alizarin Crimson is red plus a little blue. The bias of Phthalo Blue is green, and the bias of Ultramarine Blue is red.
See the Color Building Block for more information.