The Essenes, a Jewish sect of the first century CE, hid the Dead Sea Scrolls (and other artifacts) from the Roman occupiers in caves near Qumran. Bedouin shepherds discovered the first of the scrolls 70 years ago.
Since the discovery, the scrolls have generated a lot of scholarly buzz, as archaeologists and physical scientists worked together on the find.
Two copper scrolls are among the most talked-about items, but animal skin and papyrus scrolls are also fascinating to scientists.
How can chemistry assist with the examination and preservation of ancient documents such as this?
Chemical Preservation of the Copper Scrolls in 1956
Experts do not regard the copper scrolls as ‘holy;’ they seem to be an inventory of treasures. Written in a Hebrew dialect that included Greek letters, the copper scrolls intrigued both archeologists and physical scientists.
A September 1956 issue of Chemical and Engineering News reported lab analyses and preservation efforts of the copper scrolls (and other Qumran scrolls).
The extensive corrosion of the scrolls made their handling difficult, and these ancient copper artifacts appeared irreparable. Chemists and material scientists (mechanical engineers) worked for approximately five years to restore many of the copper fragments.
The scientists of the 1950s utilized methods of the time to restore the copper scrolls. Initially, they used dental implements to remove desert minerals encrusted on the scroll. The next step was to reverse the copper corrosion back to solid metal. The procedure is a ‘reduction reaction.’
Copper Scroll Corrosion
Weathered copper, as you may have noticed, has a crusty coating on the surface (as you see on a corroded copper penny). The green-blue coating illustrates how the copper reacted with the weather elements.
The metal from the archeological site was not a standard piece of copper. Some parts of the scroll contained tin (implying bronze: a copper-tin combination).
In addition, the scrolls, weren’t just weathered – they were in a state of near disintegration, and were coated with Copper Oxides.
According to the Chemical and Engineering News article, Copper oxychloride (H3ClCu2O3) and Copper oxide (Cu2O) re the predominant types of copper oxides coating the scrolls.
To open the scrolls, the scientists cut the artifact into smaller pieces and then used a chemical reduction process to reverse the corrosion process.
The process the researchers used is remarkably similar to washing a surface of sheet metal:
Newer Evaluation Methods
The techniques of the 1950s relied on ‘wet’ chemistry, which uses repetitive testing and experimentation on archeological samples.
In the utilization of spectroscopy, dry chemical methods give chemists and physical scientists the means to quickly test on small sample sizes. The production of chemical waste is minimized as well.
Shine x-ray light upon pure copper, and the corresponding measurement yields a distinctive and repetitive pattern as hard data (a reproducible analysis).
The ‘X-ray’ pattern of the copper scroll-artifact contains primarily copper and copper oxides. Further discernment indicates the types and amounts of oxide. Where one copper artifact may contain only one kind of oxide, the ‘scroll’ showed two types of oxide.
The methodologies the researchers followed (in 1956) were advanced technologies at that point, but with the techniques of today, the original scholars would have required far less time to restore the copper scrolls.
The Papyrus and Animal Skin Scrolls from the Qumran Caves
The majority of scrolls found in the Qumran caves were made from animal skins and papyrus. Some skin scrolls were in a state of disintegration, while others fared better.
For archaeologists and historians, keeping the ink legible was a key concern during work to preserve the scrolls. International teams of scientists first attempted to discern the composition of the ink.
For decades, researchers debated the origins of the black ink.
However by the mid-1990s most of the research concluded the black texts were of two types: carbon-based and an un-confirmed metal.
The exact composition of the metal-ink is still debated. Here is an excerpt from a publication of the American Chemical Society by Zvi Koren in 2014:
Preserving Ancient Texts Via Chemistry
Archaeology allows us to look into the past. However, in order for scientists to properly examine and maintain artifacts, it’s necessary to preserve them. In many cases, chemistry makes that possible.
The Qumran scrolls are still examined by scholars; past use of chemistry has helped preserve them for this research. Integrity of ancient artifacts helps illuminate history.