A team of Washington State University (WSU) mechanical and materials engineers successfully recreated the missing base formula for the world’s oldest synthetic pigment, Egyptian Blue.
Egyptian Blue was valued in ancient times for its resemblance to expensive turquoise and lapis lazuli. However, the research team notes that the exact method of preparing the coveted dye “was largely forgotten” by the Renaissance period.
The WSU team’s discovery reveals a variable base recipe for creating the unique hue and affirms the pigment’s purported optical, magnetic, and biological properties. They believe recreating the formula offers a previously unavailable view of this elusive ancient technology and may have unexpected 21st-century technological applications.
“We hope this will be a good case study in what science can bring to the study of our human past,” said John McCloy, first author on the paper detailing the team’s findings and director of WSU’s School of Mechanical and Materials Engineering. “The work is meant to highlight how modern science reveals hidden stories in ancient Egyptian objects.”
Egyptian Blue: A Formula Missing for 5,000 Years
Ancient Egyptians used Egyptian blue in wood painting and stone art, and dyed a papier-mâché-type material called cartonnage. However, like the construction of the enigmatic pyramids, the process for creating the world’s oldest synthetic dye wasn’t recorded. As a result, scientists have been forced to evaluate ancient Egyptian artifacts painted with Egyptian Blue without potentially critical information.
Because the WSU effort to recreate the mythical formula overlapped two disparate scientific disciplines, the team included a mineralogist and an Egyptologist. They also received support from the Carnegie Museum of Natural History and the Smithsonian’s Museum Conservation Institute.
Before taking their work into the lab, the team evaluated existing examples of ancient artifacts dyed with Egyptian Blue. According to the researchers, the first thing they noticed was that the color was far from uniform. Instead, Egyptian ‘Blue’ samples ranged from deep blue to dull, gray, or green. They suspected this variation was likely due to different preparation methods employed by artisans in varied locations.
“You had some people who were making the pigment and then transporting it, and then the final use was somewhere else,” McCloy explained. Still, the team suspected there was a base formula to all Egyptian Blue that was known as recently as Roman times but has since been lost to history.
ReCreation Reveals Pigments’ Base Formula
Back in the lab, the WSU team started their recreation effort by developing 12 possible Egyptian Blue recipes based on materials available to artisans 5000 years ago. Although each recipe was different, all included some combination of silicon dioxide, copper, calcium, and sodium carbonate.
Next, several combinations of the recipes were heated to about 1,000 degrees Celsius. Once again, the research team varied the formulations by heating them for between one and 11 hours. The team says these cooking ranges were designed to “replicate temperatures that would have been available for ancient artists.”
After each sample was cooled, the team used microscopic analysis techniques to study its chemical composition. According to the team’s statement, these modern techniques “had never been used for this type of research,” comparing their chemical formulations to two ancient artifacts colored with Egyptian Blue. As hoped, the close-up comparison between their modern formulations and the ancient artifacts showed how and where the dye was made affected its color.
“One of the things that we saw was that with just small differences in the process, you got very different results,” McCloy said.
After more analysis, the team found that getting the “bluest” color only required a formulation containing about 50% of the “blue-colored components.” The team says it was totally unexpected that one could make Egyptian Blue in several different ways, as long as they followed the base formula.
“It doesn’t matter what the rest of it is, which was really quite surprising to us,” said McCloy. “You can see that every single pigment particle has a bunch of stuff in it — it’s not uniform by any means.”
Exploiting Ancient Dyes’ Properties for Modern Technological Applications
In the study’s conclusion, the researchers note the resurgence of interest in Egyptian Blue because previous research indicated it possesses interesting optical, magnetic, and biological properties that may have applications in modern electronic devices. McCloy, who also has a master’s degree in anthropology, says accepting the museum’s challenge to reproduce the recipe for a display “started out as something fun to do.” However, the engineer also noted that “there’s a lot of interest in the material” from the broader scientific community.
For example, the 5,000-year-old pigment emits light in the infrared, a part of the electromagnetic spectrum invisible to the human eye. The team says this property unlocks the potential to use Egyptian Blue for fingerprinting or making counterfeit-proof inks.
They also note that the dye has a “similar chemistry” to high-temperature superconductors.
Christopher Plain is a Science Fiction and Fantasy novelist and Head Science Writer at The Debrief. Follow and connect with him on X, learn about his books at plainfiction.com, or email him directly at christopher@thedebrief.org.