SCIENTISTS DUPLICATE THE RARE EGYPTIAN BLUE, THE GLOBE’S OLDEST SYNTHETIC PIGMENT
Egyptian blue, the oldest synthetic pigment in the world, was created approximately 3300 BCE, more than 5,000 years ago. The recipe's specifics have been lost to time for millennia, making it impossible to fully recreate. That has now been altered by a group of Washington State University (WSU) researchers working with the Carnegie Museum of Natural History and the Smithsonian's Museum Conservation Institute.
According to a study that was published last month in NPJ Heritage Science, the scientists created 12 formulas for Egyptian blue by combining a variety of raw elements, including copper, calcium, sodium carbonate, crystalline silicon dioxide, and various heating techniques. After that, these mixes were cooked for up to 11 hours at temperatures above 1800 degrees Fahrenheit. After the samples had cooled, the researchers compared them to two ancient Egyptian artefacts and examined the pigments using contemporary microscopy and analysis methods.
“We hope this will be a good case study in what science can bring to the study of our human past,” John McCloy, first author on the paper and director of WSU’s School of Mechanical and Materials Engineering, said. “The work is meant to highlight how modern science reveals hidden stories in ancient Egyptian objects.”
Egyptian blue, also known as hsbd-iryt, or "fake lapis lazuli," in Egyptian, provided a low-cost alternative to minerals such as lapis lazuli, turquoise, and indigo millennia ago. Despite its name, the exact shade of Egyptian blue used to decorate everything from wood and stone to beads and amulets can vary depending on its ingredients and processing time, ranging from rich navies to muted greys or greens. However, the pigment gradually lost its use with the fall of the Roman Empire, and by the Renaissance, the process of making it was mostly forgotten, according to a statement from WSU.
“You had some people who were making the pigment and then transporting it, and then the final use was somewhere else,” McCloy said. “One of the things that we saw was that with just small differences in the process, you got very different results.”
Actually, the results showed that only roughly half of the blue-colored components were required to produce some of the most saturated, bluest colours. McCloy added that, in light of new, high-tech uses in our contemporary period, Egyptian blue has recently seen a "resurgence of appeal." According to the researchers, the pigment can be used for fingerprinting, counterfeit-proof inks, and other applications because it emits light in the near-infrared portion of the electromagnetic spectrum, which is invisible to humans.
“It started out just as something that was fun to do because they asked us to produce some materials to put on display at the [Carnegie Museum], but there’s a lot of interest in the material,” McCloy added.
Though opening up a world of intriguing possibilities today, it’s important to honour the cultural and artistic significance Egyptian blue once carried.
“The production of Egyptian blue was a highly sophisticated process, made possible only within a well-developed cultural and technological context,” Moujin Matin, an archaeologist at the University of Western Ontario and who wasn’t involved in the recent research, told Chemistry World. “Culturally, the prominence of blue in religious symbolism and daily life gave the pigment special significance, ensuring its sustained value and use.”
WSU's samples are currently on exhibit at the Carnegie Museum in Pittsburgh, Pennsylvania, and will soon be included in the museum's new, permanent gallery on ancient Egypt.