Cassel / Cologne Earth is thought to have been in use since the Renaissance period and mainly in Holland and England. Unfortunately, due to the difficulty identifying organic materials using modern analytical methods, the use of this pigment can only be suspected in a number of paintings. The earliest date Cassel / Cologne Earth may have been used is during the early 1500s: an organic brown pigment was found in two paintings of 1500 to 1511 attributed to Gerard David (circa 1460-1523). Organic brown pigment was also found in paintings by Velazquez (1465-1524).

Handbooks and literature of the 17th century include recommendations for its use, confirming that it was part of painters’ palettes in that century. Karel van Mander, in his Het Schilder-Boeck (1604) recommends Cologne Earth for the shadows ‘of the flesh’ and Willem Beurs mentions Cologne Earth in his De Groote Waereld in ‘t kleen geschildert  (1692).

The pigment was used in oil painting, mainly as a glaze over dark areas, and in later centuries in watercolour. It was not restricted to fine art: it was used on sculptures, walls, wall and decorative papers, in woodworking and even put in snuff!

A recipe by the celebrated painter Jan Davidsz. de Heem (1606-1683/4) survives, in which he recommends a mixture of lead white, lake, bice and earth of “colon” for painting the yeast residue on grapes and other fruit:

Rubens (1577-1640) is known to have included the pigment on his palette: he mixed it with ochre, creating a warm transparent brown which ‘held up well, particularly in resin varnish’. Van Dyck was Rubens’s pupil and collaborated on a number of paintings with him, so Cassel / Cologne Earth may have entered his palette at that time.

Rembrandt van Rijn (1606-1669) used Cassel / Cologne Earth to create the dark backgrounds we know him so well for. In his painting Saskia van Uylenburgh as Flora (see below), Rembrandt used a mixture of yellow ochre, bone black, a small amount of lead white, and Cassel / Cologne Earth for the background areas. Cassel / Cologne Earth was most likely used as a glaze.

Now I’ve added Cassel Earth to my own palette, I’ve been using it in my backgrounds as well. Below is a painting of a Cornish shell; the background, a layer of Cyprus umber, was glazed with Cassel / Cologne Earth to create a deep and dark background bringing out the shell.

Today, due to the moderate lightfastness of NBr8, genuine NBr8 paint is sadly no longer widely available to artists, except via the fine art materials manufacturer Vasari (USA). Instead, most manufacturers use PBr8: an inorganic pigment that mainly contains manganic hydroxide and is mostly synthetic. Unfortunately, they all claim to be genuine Vandyke Brown – suggesting that the centuries’ old confusion between organic and inorganic Vandyke Brown may be alive and kicking today.One modern study on the lightfastness of NBr8 supported by The National Gallery of Art, Washington, has shown that discolouration of NBr8 may occur after an equivalent of 20-100 years exposure to museum lighting, confirming that the pigment is of intermediate light stability (Feller and Johnston-Feller, 1997). In this experiment NBr8 was glazed directly onto a bright background before exposure to light, thereby allowing more light reflection than would have been the case if NBr8 was glazed onto a dark background – the traditional 17^th century method of working with this pigment. This modern conclusion of lightfastness may therefore not reflect the fate of this pigment used in the 1600s. Unfortunately this does not change anyone’s mind and most artists don’t look further than PBr8. This is a shame as the depth of colour and magic of this early pigment, and the other old pigments, is unparalleled in modern colours.