Rare or Unidentifiable Pigments: Schijtgeel & Vivianite

Origin, History and Characteristics of Schijtgeel

(schijtgeel = vivanite = blue ochre, ocre martiale bleue, blauer oker)

A yellow dye for producing artists' pigments frequently mentioned in the Dutch sources of the seventeenth century was schijtgeel. Schijtgeel is a collective name for organic, yellow dye stuffs gained from various dyeing plants, berries and woods. There existed different recipes for its production, for instance one from a collection of recipes by Willem Pekstok from Amsterdam, a producer and dealer of paint materials in the late seventeenth century, mentioning weld, yellow wood (probably from Old Fustic) and the berries from the Purgin resp. the Avignon buckthorn (Rhamnus catharticus/Rhamnus infectoria) for the production of schijtgeel. These dye stuffs, composed of several organic dyeing material, were available in different qualities, partially as pure lakes or adsorbed on chalk or lead white, and the artist decided primarily from the hue and the covering qualities which product to buy, certainly not from its substances.

Origin, History and Characteristics of Vivianite

Vivianite, named after the English mineralogist F. G. Vivian, is a rare mineral of secondary origin associated with pyrite in copper and tin veins, and is a hydrated iron phosphate of a blue to green color. Vivianite has rarely been found on European easel paintings, but it has been identified in medieval paintings in Germany and in English medieval polychromy. The School of Cologne used it to depict skies in the thirteenth and fourteenth century.

Vivianite is found principally in two environments: In the oxidized upper layers of ore deposits, where it may appear as dark indigo, blue-black, or green crystals. It is also found in organic rich environments often lining the inside of ancient mollusk shells, but sometimes associated with bones, decaying wood and other organic material. Mineral from the latter environment is sometimes collected for use as pigment, but in practice it is more frequently gathered from ore deposits, such as peat bogs and marshy-lakes. Extracting soft, friable vivianite concretions from viscous, dense clayey soil is time-consuming. Once obtained it is necessary to thoroughly wash it to remove clay and organic residue from each grain of vivianite. The labor expended in this operation is rewarded by a high-quality end product. Vivianite is generally stable and dark blue or green in color, though the mineral may be colorless when first exposed. This color transformation is a special feature of vivianite found in peat bogs.

Schijtgeel and Vivianite in Vermeer's Painting

The recent restoration of Vermeer's Procuress (2002–2004) has revealed two new pigments which have been undetected as of yet, an organic yellow pigment and a rare blue one. The yellow pigment is an organic dye but not as a lake (with large quantities of aluminium), but with lead white as the substrate. An exact identification of the yellow-brown pigment was not possible to make with this sample. According to the publication^{Uta Neidhardt and Marlies Giebe, eds., Johannes Vermeer. Bei der Kupplerin (Dresden, 2004). Heike Stege, Cornelia Tilenschi, and Achim Unger, "Bekanntes und Unbekanntes. Neue Untersuchungen zur Palette Vermeers in der 'Kupplerin,'" 76–82, specifically 78.} dedicated to the restoration in question, it is very likely that Vermeer himself didn't know the exact nature of his yellow pigment although it could be a fugitive pigment called schijtgeel.^{Perhaps painters chose their pigments according to the desired color rather than their supposed chemical make-up.}

Another unexpected identification made during the mentioned restoration was that of a rare pigment, a mineral iron phosphate probably vivianite. It appears only in the upper paint layer of the gray-blue and green-gray areas of the carpet (fig. 1). The instable pigment has degraded making a hardly definable blue-gray-brown dominating significant parts of the carpet. Verifications of the use of vivianite in painting are not very numerous: in Europe mainly in the Middle Ages. More directly related to Vermeer's oeuvre is a recently published study by Marika Spring with the verification of vivianite in several paintings by the Dordrecht painter Aelbert Cuyp (1620–1691).^{Marika Spring, "Pigments and Colour Change in the Paintings of Aelbert Cuyp," in Aelbert Cuyp, exh. cat., National Gallery of Art, Washington, 7 October 2001–13 January 2002, ed. Arthur K. Wheelock Jr. (Amsterdam; London, 2001–2002), 65–73.} In a recent examination of a painting by Dou from 1646 (Alte Pinakothek München) a pigment rich of iron phosphate was detected in the green parts of the vegetation. Therefore, a frequent use of vivianite or other forms of iron phosphate in Dutch seventeenth-century painting seems more plausible now. Marika Spring supposes a bog iron ore in the peat bogs as a possible source for vivianite in the Netherlands.^{Marika Spring, "Pigments and Colour Change in the Paintings of Aelbert Cuyp," in Aelbert Cuyp, exh. cat., National Gallery of Art, Washington, 7 October 2001–13 January 2002, ed. Arthur K. Wheelock Jr. (Amsterdam; London, 2001–2002), 66.} The occurrence of vivianite as a pigment is sufficiently rare to provide information on dating and provenance.