Vermeer's Palette: Azurite

Origin, History and Characteristics

(Cendree, Mountain blue, Copper blue, Ongaro, Azure Biadetti of Spain, Azure of the Magna)

Latin borrowed a Persian word for blue, "lāzaward," which in the form of lazurium became azurium, and gave us our word azure. Azurite is composed of a basic carbonate of copper, found in many parts of the world in the upper oxidized portions of copper ore deposits. Azurite mineral is usually associated in nature with malachite, the green basic carbonate of copper that is far more abundant. Azurite was the most important blue pigment in European painting throughout the middle ages, and Renaissance by contrast, despite the more exotic and costly ultramarine having received greater acclaim "While a subtle range of blues could be achieved by controlling the particle size of azurite, its green undertone was not always desired; this was adjusted however by mixing in red lakes and, as noted, applying layers of ultramarine on top. The situation changed in the early 1500s with the invention (or more correctly, the re-invention) of smalt. Just when silver mines were becoming more difficult to exploit and less profitable, further economic pressure came as vast quantities of silver were discovered in the New World and imported into Europe, especially through Spain.

The major sources of azurite in Europe were present-day Germany, Hungary, Austria and Central Europe. Canny mine operators and owners therefore began to exploit their mines for rarer metal ores and minerals that could be used by the color industry."^{B. H. Berrie, "Mining for Color: New Blues, Yellows, and Translucent Paint," Early Science and Medicine 20, nos. 4-6 (2015): 308-334, https://doi.org/10.1163/15733823-02046p02.} Azurite—then commonly called azzurro d'Alemagna—was often used for draperies, particularly in works by Duccio and his circle.

To prepare a color from azurite, a lump of it is ground into a powder (fig. 2), and sieved. Coarsely ground azurite produces dark blue, and fine grinding produces a lighter tone; however if not ground fine enough, it is too sandy and gritty to be used as a pigment. The medieval system included washing it to remove any mud and then separating the different grains by some process of levigation. If plain water is used it is a slow, laborious process, so they used solutions of soap, gum and lye. When azurite is washed, the very fine particles are rather pale, greenish sky-blue, and not much admired for painting. The best grades of azurite for painting were coarse: not sandy, but so coarse that it could be quite laborious to lay them on.

Glue size was often used as a binder to hold the pigment grains firmly in place. It was necessary to apply several coats of azurite to produce a solid blue (fig. 1), but the result was quite beautiful. The actual thickness of the crust of blue added to the richness of the effect, and each tiny grain of the powdered crystalline mineral sparkled like a minute sapphire—especially before it was varnished. Due to the coarseness of azurite it was difficult to use in detail.

Azurite in Vermeer's Painting

In the The Officer and Laughing Girl, azurite is found under a layer of natural ultramarine mixed with lead-tin yellow and traces of lead white in the area corresponding to the shadowed area of the green tablecloth. Azurite was also detected in some of the light gray areas of A Maid Asleep. A

In the The Little Street, the sky was underpainted with lead white, over which the chimneys on the V-shaped roof line were painted. Azurite was used in the underpainting of the three upper windows, including sills and surrounds, of the right house, followed by a creamy yellow layer. The sequence of paint layers is reversed in the ground-floor windows of this house. The foliage was painted with an azurite and lead-tin yellow mixture, three different shades of an ultramarine and lead white mixture, and pure ultramarine.^{Arthur K. Wheelock Jr. and Ben Broos, Johannes Vermeer (London and New Haven: Yale University Press, 1995), 102.} Azurite is also found mixed with lead-tin yellow in the green window shutters of the Little Street (fig. 3).

"In a few instances, smalt and azurite layers in Vermeer's paintings have been shown to have a protein binding medium, for which there are several recipes in the treatises, among the suggestions made to prevent blue pigments becoming altered by the yellowing of the oil film. Part of the problem was that the better the quality of blues such as ultramarine, azurite, and smalt, the larger their particle size, which caused them to sink in the oil, producing a greenish effect."^{Nicola Costaras, "A Study of the Materials and Techniques of Johannes Vermeer,"in Vermeer Studies eds., Vermeer Studies (Studies in the History of Art Series) (Washington, DC: National Gallery Washington, 1998), 157.}

Vermeer seems to have used azurite in light grays and mixtures of green where the brilliance of ultramarine would not have been appreciable. Like other painters of the time, Vermeer may have used azurite as a base color on which the far more costly natural ultramarine was paintedr over, for economical reasons.