Although Van Dyke Brown has the name of Flemish Baroque artist Sir Anthony van Dyck because it was said to be first used by him, in actual fact it was Rubens who pioneered the use of the pigment and since Anthony van Dyck was a pupil and principal assistant of Rubens, the young Van Dyck would have been required to use this colour by his master.
Van Dyke Brown had a very different name in those days, as it was called either Cassel Earth or Cologne Umber, both names referring to the fact that it was mined in the vicinity of Cologne in Germany. It was essentially a Raw Umber, which had a high portion of lignite in it. Lignite is brown coal. This original Van Dyke Brown colour, as used by Rubens and Anthony Van Dyck, has stood up well over time but unfortunately the pigment could be variable in quality and the lignite portion was prone to degrading. Unscrupulous colourmen added to the problems by using bitumen as a substitute for the best grades of Cassel Earth and so while the colour remained very popular, it gained a reputation by the 19th century as an unreliable colour and when the fashion for paintings containing a lot of dark brown passed, sales of the colour declined as well.
Chemical Description: Natural iron oxide
Pigment Number: PBr7
Lightfastness Rating: ASTM I
Pigment Opacity: Semi-Transparent
Paint Opacity: Opaque