Egyptian green

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In Egyptian Green is an olive to blue-green kupfersilikatisches pigment . In terms of its composition, it is very similar to Egyptian blue . Together with Egyptian blue, it is one of the oldest synthetically produced pigments in the world. A use has so far only been proven for ancient Egypt .

history

The oldest finds of Egyptian green date from the 6th Dynasty (2347–2216 BC). It was identified in the graves of Unas and Chenti in Thebes , as well as in another grave in el-Chocha . However, these early finds are also occasionally assumed for decomposition products of Egyptian blue and the manufacture of the pigment is only suspected from the 18th dynasty .

In the Old and Middle Kingdom , the pigment was used only rarely and irregularly, so that, if it was found before the Second Intermediate Period, it is questionable whether the pigment was consciously produced or whether it comes from a failed production of Egyptian blue. Examples of the use of Egyptian green are a painted stele from the 11th Dynasty , as well as fragments of a painted stone relief from the early 12th Dynasty .

In the New Kingdom (1532–1070 BC) the number of works of art painted with Egyptian green increased. Due to the frequency of use, specific production must be assumed. Egyptian green is often found in the tomb of Queen Nefertari from the 19th dynasty , but the pigment was also found in tombs from Thebes, Abydos , El Kab and Tell el-Amarna .

With the end of the New Kingdom, the pigment disappears. The last evidence can be found in the Third Intermediate Period , for example on a wooden coffin from the 21st Dynasty .

The use of the pigment was always limited to Egypt.

In 1975, Egyptian green was first identified by Noll and Hangst.

Manufacturing

There are no ancient Egyptian traditions for the production of Egyptian green, nor is there any mention in ancient sources, so that experimental research was necessary to rediscover the production of the pigment.

Four basic substances are required for the production of Egyptian green: silicon dioxide , calcium oxide , alkaline flux and copper oxide.

There are numerous raw material sources for silicon dioxide and calcium in Egypt. As sand, silicon dioxide is available almost everywhere and in unlimited quantities. Many sands are also calcareous, i.e. contain calcium. Limestone can also be found in the hills along the Nile Valley between Cairo and Esna . Alkali-containing fluxes were used in the form of natural soda or salty vegetable ash. Natural soda can be found in the dried up salt lakes or river beds in the desert areas, such as in Wadi Natrun in Lower Egypt or in El Kab in Upper Egypt . Copper had been in use in Egypt since the Neolithic , but no copper deposits were found along the course of the Nile. Copper was therefore imported and mined in the form of copper ores outside the Nile Valley, for example in Fenan , Timma and Sarabit al-Chadim . The use of these raw materials extends well beyond the beginnings of pigment production.

The ingredients were ground to a fine powder and mixed together. About 5 parts quartz, 2 parts lime, 2 parts copper and 1 part flux were used for this. The powder was then heated for 24-48 hours at a temperature between 900 and 950 ° C. This creates a glass-like blue mass. This mass is ground and reheated. This increases the proportion of blue. This process is repeated several times until the temperature has been increased to over 1000 ° C or a reducing furnace atmosphere was present. This increase in temperature ultimately results in Egyptian green.

literature

  • Jörg Klaas: Studies on Egyptian Green. Diploma thesis at the Technical University of Munich, Munich 2006.
  • Nicholas Eastaugh, Valentine Walsh, Tracey Chaplin, Ruth Siddall: The Pigments Compendium: A Dictionary of Historical Pigments. 1st edition, Elsevier Butterworth - Heinemann, Oxford 2004, ISBN 978-0-7506-4553-9 , p. 148.