Han blue

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Han blue or Han blue is the modern term for a synthetic blue barium copper silicate , which has been proven as a pigment in China since the Zhou dynasty (1122 / 1045–770 BC) . The original name of the pigment is unknown.

Wall painting in a tomb in Zhucun 朱村, Henan Province ; Painted with Han Blue and Han Purple pigments, around 220 BC. Chr.

history

Han blue is a synthetic pigment that has been identified in China since the Zhou dynasty (1122/1045–770 BC). Han blue had its peak in the Han dynasty (206 BC – 220 AD), from which most of the dated objects come. This is how the pigment got its modern name Han blue. It was mainly used to paint ceramics, metal objects and wall paintings. It also appeared in ceramic techniques for making glazes and cast pearls. After the end of the Han dynasty, the formerly popular pigment could no longer be detected, which speaks for a sudden disappearance of the pigment.

Since the pigment was not only known in China in the Han Dynasty, the term Chinese blue is also often used. However, this should be avoided, as other pigments such as Prussian blue are also referred to as Chinese blue.

Manufacturing

With han Blue is a blue Bariumkupfersilikat which as a natural mineral Effenbergerit occurs. However, this is very rare and has no cultural-historical significance. The barium copper silicate used as the pigment is therefore a synthetic pigment. It was invented by Chinese alchemists through chemical experimentation .

No contemporary sources exist for the manufacture of the pigment, so the exact manufacturing process is not known. In any case, it is both difficult and very complex and requires technical knowledge and experience.

The most likely method of manufacture requires a barium mineral such as barite , a copper mineral such as malachite or azurite, and sand containing quartz. Han blue often also contains lead, presumably as a flux to lower the manufacturing temperature. These raw materials are crushed, mixed and heated in the oven at a constant temperature. After 10 to 24 hours, the intermediate product Han violet is formed . Han blue, on the other hand, takes twice the time.

The Han blue was then presumably traded in octagonal pigment sticks, which were then pulverized before use.

The production is therefore very similar to the production of Egyptian blue . A widespread theory therefore says that the technology for making Egyptian blue came to China via the Silk Road , where it led to the invention of Han blue. However, this is unlikely, as no Egyptian blue has yet been detected in China. In addition, long-distance trade via the Silk Road did not come into being until the 2nd century BC. BC and thus long after the invention of Han blue to its peak. Furthermore, there is no reason why the Chinese should have replaced the cheaper components of Egyptian blue with the more expensive components of Han blue.

Composition and structure

Han blue is a synthetic barium copper silicate with the formula BaCuSi 4 O 10 . There are three other stable phases of barium copper silicate known: the Han violet and two other unnamed phases.

Microscopically, it is the antique pigment and tetragonal platelets or mostly their fragments next to humped, glass frit-like particles. Thus, it is also very similar in composition to Egyptian blue .

Modern products differ in particle size and shape from the ancient pigment.

literature

  • H. Anthamatten, C. Cataneo, G. Kremer: Color Pigments - Dyes - Color Stories . Winterthur Trade Museum. Alataverlag, Elsau 2010, p. 34.
  • N. Eastaugh, V. Walsh, T. Chaplin, R. Siddall: The Pigments Compendium - A Dictionary of Historical Pigments . Elsevier Butterworth - Heinemann, Oxford 2004.
  • H. Berke, HG Wiedemann: The Cemistry and Fabrication of the Anthropogenic Pigments Chinese Blue and Purple in Ancient China. In: East Asian Science Technology and Medicine. Vol. 17, Tübingen 2000, pp. 94-119.
  • H. Berke: The Invention of Purple Pigments in Ancient Times. In: Chemical Society Reviews. The Royal Society of Chemistry, London 2007, pp. 15-30.
  • F. Delamare: Blue Pigments - 5000 Years of Art and Industry . Archetype Publications, London 2013.
  • EW FitzHugh, LA Zycherman: An Early Man-Made Blue Pigment from China - Barium Copper Silicate. In: Studies in Conservation. Vol. 28, IIC, London 1983, pp. 15-23.
  • EW FitzHugh, LA Zycherman: A Purple Barium Copper Silicate from Early China. In: Studies in Conservation. Vol. 37, IIC, London 1992, pp. 145-154.