"Yellow Deep is a rich golden yellow that may remind some of Vincent Van Gogh???s sunflowers. As it was, Vincent Van Gogh he used a golden shade of Chrome Yellow which is both very poisonous and can sometimes turn brown when it reacts with other colors. No such problems with Yellow Deep as it is both non-toxic and very lightfast. This particular pigment is described as a diarylide which means that the number of carbon and hydrogen atoms in the color molecule is doubled. This alters the color somewhat but also increases lightfastness slightly.
Most of these newer organic colours have become available since the 1960???s and originated with the large amount of research dollars poured into the search for new automotive colors. Artists need to be thankful to the automotive industry as cars have been subject to intense sunlight outdoors for many years and so any color that is good enough to be used as a car color is certain to have enough lightfastness to be used in artists paints. In this case we benefit with a color that is perfect for painting flowers and golden wheat field???s and sunlight and all the other sorts of things that inspired Van Gogh.