HMN 2025: How 5,000-year-old Egyptian blue pigment recreated utilizing historic strategies

A crew of Washington State University-led researchers has recreated the world’s oldest artificial pigment, known as Egyptian blue, which was utilized in historic Egypt about 5,000 years in the past.

Reporting within the journal npj Heritage Science, the researchers used quite a lot of uncooked supplies and heating occasions to develop 12 recipes for the pigments, offering helpful info for archaeologists and conservation scientists who study the traditional Egyptian supplies. The work was performed in collaboration with the Carnegie Museum of Natural History and the Smithsonian’s Museum Conservation Institute.

“We hope this will likely be a great case study in what science can convey to the review of our human past,” mentioned John McCloy, first writer on the paper and director of WSU’s School of Mechanical and Materials Engineering. “The work is supposed to spotlight how trendy science reveals hidden tales in historic Egyptian objects.”

While Egyptian blue pigment was valued in historic occasions, there’s restricted archaeological proof of the way it was made. It was used as an alternative choice to costly minerals like turquoise or lapis lazuli and was utilized in portray wooden, stone, and a papier-mâché-type materials known as cartonnage. Depending on its components and processing time, its colour ranges from deep blue to boring grey or inexperienced.

After the Egyptians, the pigment was utilized by Romans, however by the Renaissance interval, the information of the way it was made was largely forgotten.

In latest years, there was a resurgence of curiosity within the pigment as a result of it has fascinating optical, magnetic, and organic properties with potential new technological functions, mentioned McCloy. The pigment emits mild within the near-infrared a part of the electromagnetic spectrum that folks cannot see, which implies it may very well be used for issues like fingerprinting and counterfeit-proof inks. It additionally has the same chemistry to high-temperature superconductors.

“It began out simply as one thing that was enjoyable to do as a result of they requested us to provide some supplies to placed on show on the museum, however there’s a whole lot of curiosity within the materials,” mentioned McCloy, who, along with being a professor in supplies science and engineering, has a grasp’s diploma in anthropology.

To perceive its make-up, the researchers, together with a mineralogist and an Egyptologist, created 12 completely different recipes of the pigment from mixtures of silicon dioxide, copper, calcium, and sodium carbonate. They heated the fabric at about 1000 levels Celsius for between one and 11 hours to copy temperatures that will have been out there for historic artists.

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After cooling the samples at varied charges, they studied the pigments utilizing trendy microscopy and evaluation methods that had by no means been used for this sort of analysis, evaluating them to 2 historic Egyptian artifacts.

Egyptian blue included quite a lot of blue colours, relying on where they have been made and their high quality. The researchers discovered that the pigment is very heterogeneous.

“You had some individuals who have been making the pigment after which transporting it, after which the ultimate use was elsewhere,” mentioned McCloy. “One of the issues that we noticed was that with simply small variations within the course of, you bought very completely different outcomes.”

The researchers discovered that, the truth is, to get the bluest colour requires solely about 50% of the blue-colored parts.

“It would not matter what the remainder of it’s, which was actually fairly stunning to us,” mentioned McCloy. “You can see that each single pigment particle has a bunch of stuff in it—it isn’t uniform by any means.”

The samples created are presently on show at Carnegie Museum of Natural History in Pittsburgh, Pennsylvania and can turn into a part of the museum’s new long-term gallery targeted on historic Egypt.