Since prehistory man has attempted to reproduce the deep blue colour of a clear summer sky. The heavenly blue that is thought to house and represent the unpredictable, divine powers.
Blue is a rare colour in our earth’s colour-scheme which is dominated by floral greens and the many hues of ochres. Easy to find ochres used in colouring the earliest art, supplemented with the whites of lime and charcoal blacks.
Blue and green pigments and paints, and the words used to name them, appeared much later.
As usable pigments and stable colours they were hard to come by, they were either hidden in ore, like cobalt and copper, or embedded in enclosing rock, like lapis lazuli.
Azurite is the oldest source for blue pigment, first used in the ancient cultures of the Middle East. It is a member of the copper-family, hence it’s blue is tinted with a green hue, making it less suitable to imitate the warm blue of the heavens.
For about 6000 years the only genuine alternative was the pigment made from the deep blue variety of lapis lazuli. However, it’s scarcity meant that for most people it was unavailable or unobtainable. For the whole of Eurasia and Africa the only known sources were from the remote mines of the hostile Kokchan-valley in Badakshan, modern Afghanistan.
A very welcome alternative became available around 5000 years ago as a product of the expanding Middle-Eastern glass-industries. Red, green, yellow and blue glass grew to be the man-made alternative for colourful but rare gemstones, easily manipulated in moulds of various sizes.
The blue variety of glass, the imitation lapis, was made by adding cobalt to the basic glass-ingredients.
The famous funeral mask of Tutankhamen is a beautiful example of the use of blue cobalt glass and enamel in combination with genuine lapis lazuli.
Christianity established as the main religion on the European continent during the Middle Ages. With it’s increasing power, the need for representative and dominating symbols grew, culminating in the extraordinary piece of architecture: the cathedral.
|the intense blue of the Saint Denis Cathedral stained-glass Rose window|
The abbot of Saint Denis, Suger (ca. 1081-1151) is considered to be the initiator of the first grand stained-glass windows. They were commissioned for the far-reaching expansion of the monastery’s church, turning it into the first known cathedral. For his church, Suger wanted the windows to represent ‘.. the inaccessible light where God lives’. Light which could only be of the most intense, enveloping blue.
And thus were they created.
Cobalt, the raw material used in colouring blue glass was a by-product from the mining of silver and other ores. It was used to produce the so called saffer, after sapphire. Not the gemstone we know under that name, but the lazuli-stone, then considered far more precious than gold and sapphire. Somewhere the idea was had by someone to turn Saffer into smalt by grinding the blue lumps of molten glass into a pigment. A pigment resembling lapis, but readily available and far less costly.
|a piece of smalt/saffer, as sold by Kremer Pigmente|
Painters and decorators welcomed the solution which put an end to the constant scarcity of genuine ultramarine and the unsatisfying hues of azurite. Despite it’s caprices smalt became one of the regular pigments. However, to maintain it’s colour it had to be used rather coarsely: the finer the grain, the paler the colour.
|Coarsely ground smalt, so called strooiblauw. Collection of author|
Smalt, as a warm blue, raised considerably the colour-temperature of the painter’s palette. Beautiful examples are the skies in Dutch landscape paintings, as in the ‘River-scene’ by Jan van Goyen (1596-1656).
Kobold (hence ‘cobalt’) the little blue ghost, believed by the miners to inhabit the ore, continued to play it’s games. Painters knew of the problems ill treated smalt could give; I wonder whether they could really imagine the enormous impact of discoloured smalt on their work.
Old smalt-blue can still be enjoyed today, as seen in Van Goyen’s painting, but it can also have lost it’s colour completely. Changed into a dull brown, deforming the composition and, importantly, changing the meaning of a painting. Actually diminishing all of the painter’s hard work.
The above still-life by Jan Jansz. Treck (1605-1652) is, unfortunately, a fine example. It seems an old painting displaying the golden-brown glow of age. However, we may ask ourselves does this kind of greenish china-ware exist? Does it make sense?
What we are in fact looking at is a coat of yellowed varnish in combination with a vanished blue. Linseed-oil and smalt don’t really like each other. The colour of the tiny glass-particles is eventually swallowed by the oil when not applied properly, or when the smalt is not of the right quality. What Treck originally painted was a fine blue tablecloth with a blueish background, and on the table a still-life of the most exquisite blue-white china and an expensive crystal glass. Symbols of wealth as the Dutch liked to display.