A multidisciplinary study unveils the nature of a Roman ink of the I century AD

Mirta Sibilia,Simone Pollastri,Sabina Licen,Francesco D’Amico,Chiara Schmid,Matteo Crosera,Lisa Vaccari,Gianpiero Adami,Pierluigi Barbieri,Chiaramaria Stani,Stefano Buson,Alessandro Migliori,Federica Gonzato,Lara Gigli,Giuliana Aquilanti,Jasper R Plaisier

doi:10.1038/s41598-021-86288-x

Abstract

A multi-instrumental approach combining highly sensitive Synchrotron Radiation-based techniques was used to provide information on the real composition of a dry black ink powder found in a bronze inkwell of the first century AD. The presence of Pb, Cu and Fe in the powder, revealed by XRF and ICP-OES data, leads to raise several hypotheses on their origin. The inkpot and its lid were also investigated by Hand-Held XRF, revealing a bronze alloy (Cu-Sn) with a certain amount of Fe and Pb. The lid was found to be particularly enriched in lead. XRPD, XAS and FTIR measurements showed a substantial presence of silicates and common clay minerals in the ink along with cerussite and malachite, Pb and Cu bearing-carbonates, respectively. These evidences support the hypothesis of an important contamination of the ink sample by the burial environment (soil) and the presence of degradation products of the bronze inkpot. The combined use of IR, Raman, and GC-MS evidenced that the black ink is mainly composed of amorphous carbon deriving from the combustion of organic material mixed with a natural binding agent, Arabic gum.

Highlights

A multi-instrumental approach combining highly sensitive Synchrotron Radiation-based techniques was used to provide information on the real composition of a dry black ink powder found in a bronze inkwell of the first century AD
The black ink powder found inside a bronze inkwell of the I century AD was characterized by a multi-analytical approach with a sequence of non-destructive and Synchrotron Radiation (SR)-based techniques as well as by conventional destructive methods
The co-presence of Pb, Cu and Fe, revealed by SR-X-Ray Fluorescence (XRF) and Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES), induced us to hypothesize that the black powder could belong to the mixed-ink family, for which metals were added on purpose in the formulation

Summary

Introduction

Brun et al identified the so-called “mixed ink” on some ancient Herculaneum papyri by Synchrotron Radiation (SR) X-Ray Fluorescence (XRF) This ink was produced by intentionally mixing soot or charcoal with metallic compounds, such as lead-based minerals, possibly added to enhance the ink black p igmentation[6,7]. Μ X-ray Absorption Near Edge Structure (μ-XANES), discovered that the copper-containing black carbon ink on some Egyptian papyri, coming from different time periods and geographical regions, was related to the use of soot obtained as by-products of metallurgical p rocesses[2] This shows that a multi-analytical approach is required for analyses of ancient artifacts of Cultural Heritage due to their complex nature. This means reduced dwell times, reduced spot sizes, and higher signal-to-noise ratio of the measurements, allowing the investigation of unique and precious artifacts in a non–invasive and non-destructive way

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Results

Conclusion