According to the historical evidence, the first ever man-made pigment was originated in Egypt, 5,000 years ago. It’s chemical formula, later on, was found to be calcium copper silicate. Rather than being just a color to Egyptian masterpieces such as “Nebamun hunting in the marshes”, crown of the world famous Nefertiti bust and many more, it provides the modern day necessities of chemistry and technology as calcium copper silicate but was well-known as Egyptian blue among Pharaoh’s. This is the 5,000 year old story of Egyptian blue; something beyond a pigment.
Early Egyptian artists had to satisfy themselves with earthy colors that were provided by the oils of the surface. Even though there was a mineral called lapis lazuli (is being mined in Afghanistan today) as a source of blue color, its high cost discouraged the artists. Instead, they produced pigments on their own. Blue was the first of all.
According to the documents of a Roman writer in 1st century BC, sand, copper (from minerals called azurite and malachite) and natron (a mixture of sodium compounds such as sodium carbonate) were the ingredients of Egyptian blue (CaCuSi4O10) of which the crystals can be synthesized by heating the components to 800-900 0C in the presence of calcium containing inorganic mineral: lime, which might have unintentionally supplied by the sand impurities, at that time. Their remarkable Egyptian blue synthesis provided blue color to the wall paintings, decorations, tombs, furniture, statues and later on for certain objects as well. Egyptian blue was abundantly used in the Mediterranean basin even after the end of the Roman period.
No matter whether they optimized and developed the chemical reaction or came across with it fortuitously, control of heat and oxygen supply in the pigment production undoubtedly should have been real challenges. And surprisingly, they managed to maintain the consistency of the pigment the same which is proven by the similar nature in the pigment found in tombs of Mereruka (approximately 2600-2100 BC) and in mummy coffins in the Greco-Roman period (approximately 330 BC-AD 400).
In 2009, Egyptian blue was reported with the presence of luminesce that falls near-infrared region. This luminescence effect is still detectable even the blue color content is as little as that is unnoticeable to naked eye. This ideally is a greater tool in confirming whether the old historic specimen were earlier colored or not. The conclusion that Elgin Marbles were originally painted was made by this principle.
The nature of long lasting luminescence in Egyptian blue together with its tissue penetrating ability, makes it suitable to use in biomedical analysis, telecommunications and lasers as well as an alternative for lanthanide: an expensive compound used in security inks.
Egyptian blue (or cuprorivaite) generally penetrates human tissues better than ultraviolet but with minimal body absorption. This makes it more suitable for developing more detailed and clear images of the tissues. It wasn’t until 2013 the remarkable ability to make very thin layers: nanosheets of Egyptian blue was reported. This effect is called delaminating and the sheets provided are thousand times thinner than a human hair. Researchers of University of Göttingen, Germany has published in
Nature Communications, describing the use of exfoliated nanosheets made of Egyptian Blue in bioimaging applications. To add more, as these nanosheets are composed of calcium copper silicate they are good platforms for telecommunication. The sheets produce invisible infrared (IR) radiation similar to the beams that communicate between remote controls and TVs, car door locks and other telecommunications devices.
The suitability of using the pigment as a powder in fingerprinting on complicated surfaces was revealed in 2016. Usually, in fingerprinting, a fine powder is dusted on the interested surface and picked put for investigations. However, this picking out is inefficient when the surface is shiny and patterned where Egyptian Blue became a rescue. As the smaller particles of the pigment stick properly to the fingerprint, fabulous images with fine details could be obtained, showing some lights in solving modern day crimes.
Definitely newer applications and advancements of Egyptian blue will be developed in the near future having the maximum benefit of this Pharaoh’s pigment which they would never have imagined to make a milestone in human civilization and in the development of chemistry.
References:
- https://news.artnet.com/art-world/egyptian-blue-science-1819458
- https://www.ancient.eu/image/3029/egyptian-hunting-in-the-marshes/
