All plants contain coloured substances. These pigments contained in the root, stem, leaf, flower or fruit often achieve a specially high concentration in a particular part of the plant, like red alizarin for instance in the root of the madder plant (Rubia tinctoria).

The colourants are tied in with the substance of the plant, and so are not immediately available for painting purposes. This is where the art of the plant chemist comes in. First of all the pigment must be dissolved from its bonded state, then it must be rebonded in a new form.