In this 6 minute video Cathe talks about the idea of choosing your pigments for your palette because of what values the pigments will produce. Transparent pigments produce light values, opaque pigments make middle values, and staining pigments will create good rich darks in one pass. No need to go over and over with too many layers trying to get the value you want, making your painting look overworked. This strategy for choosing your pigments will produce clean color in a minimum number of passes.There is a set of 9 basic primary pigments, which can be used to make your secondaries, and also an expanded set. Looking at a finished painting, Cathe then goes through value by value and describes the way the pigments were chosen to get the value produced. Getting the values you want does not need to be a random and iffy process. Plan on the value and go get it!