Ask any high-street printer and you’ll be told that using metallic ink is both tricky and expensive. Mind you, the printer will probably add, metallic will also make your freshly minted brochure look very modern and up to the minute.
This, sadly, turns out not to be true. Research published in the journal Scientific Reports shows that for ancient Egyptians using a metal-filled ink was standard practice for at least 300 years.
A study led by Thomas Christiansen of the University of Copenhagen in Denmark reveals that two groups of papyri – the first dating from before 88 BCE and the second extending up to the second century CE – both use ink that contains substantial amounts of copper.
The two papyrus groups are wide separated by distance as well as time, the scientists note, making it “probable that the same technology for ink production was used throughout Egypt” for three centuries or more.
To make their findings, the researchers deployed a range of imaging techniques, including radiation-based X-ray microscopy at the European Synchrotron Radiation Facility in Grenoble, France.
The analysis revealed that the inks contained copper, primarily in the form of the minerals cuprite, azurite and malachite. The fact that these were present in all the four ink variations identified, Christiansen and colleagues concluded, meant that they could not have been there by accident.
The presence of the copper provides strong clues regarding how the Egyptians sourced and made ink for printing. To do so, the scientists suggest, they made use of another practice common to their civilisation: metallurgy.
To make ink, they suggest, soot and charcoal created during the extraction process of copper from sulfurous ores was used.
The hypothesis finds support, they add, because the Egyptians also used a pigment – known as Egyptian blue – that was obtained through exploiting scrap of leftover copper found in workshops attached to temples.
Although on the evidence copper ink was already in widespread use as early as 88 BCE, Christiansen and his team note that the time of its first introduction has yet to be established.
They speculate, however, that it might be tied to a change in writing technology. The writing on all the papyri tested for the research, they note appear to have been written by Greek reed pen, rather than a traditional Egyptian reed brush.