A Study in Blue Pigments (Part 1) - Azurite

Azurite, the first blue pigment used in art, is a natural carbonate of copper usually described as bright blue or sometimes as greenish blue. Naturally occurring in Sinai and the Eastern Desert of Egypt, Azurite varies in color from deep blue to pale blue with a greenish undertone depending on such factors as the purity of the mineral and the grade or particle size of the pigment. Azurite is not a useful pigment because it is unstable in air having the tendency to cause its color to change from blue to green.
Azurite has been used as a pigment as early as the Fourth Dynasty in Egypt. It was even mentioned in Pliny the Elder’s “Natural History”, but was relatively uncommon until the middle ages when the manufacture of the ancient synthetic pigment “Egyptian Blue” was forgotten.
To prepare a color from Azurite, lump azurite is ground into a powder, and sieved. Coarsely ground azurite produces a dark blue pigment, and fine grinding produces a lighter tone. 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.
The Dutch painter Vermeer seems to have used azurite in light grays and mixtures of green where the brilliance of ultramarine, another blue pigment, 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 painted over for economic reasons. Azurite can be found in Vermeer’s the “Office and Laughing Girl” 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 table cloth. Azurite was also detected in some of the light gray areas of Maid Asleep as well as in the window green shutters of the little street.
Azurite was no doubt the most important blue pigment in European painting from the fifteenth to the middle of the seventeenth century when it was replaced by “Prussian Blue”. The paintings of that period commonly contain more azurite than natural ultramarine pigment and the two were often used together in paintings, with the solid colored and cheaper azurite pigment in under-painting and the transparent natural ultramarine in glazes.
Stay tuned to watch our next installment on blue pigments when we discuss the history and use of Egyptian Blue pigment.