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Written Artefact Profiling Guide
Written ArtefactProfiling Guide

Photo: CSMC

Written Artefact Profiling Guide

Mixed Inks

Olivier Bonnerot, Claudia Colini

What we call mixed inks are black inks obtained by blending inks (or ingredients) from the other categories (Carbon-based Inks, Plant Inks, Iron-gall Inks) and, for this reason, can be divided into three main subcategories: mixed carbon-plant inks, mixed carbon-iron-gall inks and carbon inks containing metals. Their characteristics are a combination of those of the previous types, although their prevalent behaviour is determined by the main components used. Recipes of mixed carbon-plant inks are attested in the Islamicate world from the 9th century CE, while those of mixed carbon-iron-gall inks appear later, around the 13th century. However, experimental discoveries of these inks on Coptic manuscripts from Egypt predate their usage in the greco-roman period (Ghigo 2020). In addition, recent studies have identified the presence of significant amounts of metals in carbon inks from Hellenistic and early Roman times (Delange et al. 1990; Bonnerot et al. 2020). So far, the most ancient occurrence of carbon inks containing metals date back to the very end of the 4th century BCE, at the beginning of the Hellenistic period (Nehring et al. 2021). Antique recipes from Dioscorides (with an ink made by mixing soot and ‘chalcanthon’, i.e. vitriol) and from the magical papyrus Leiden, Rijksmuseum van Oudheden, P. Leid. J 384 (= PGM XII) also seem to describe mixed inks. It is possible that mixed carbon-plant inks, as well as carbon inks with admixtures of metals, were conducive to the development of iron-gall inks.

Analytical methods are similar to the ones used for iron-gall and carbon inks:

  • 3-colour microscopy is generally used for a quick identification of the ink type.
  • It is generally followed by XRF, which allows the differentiation of iron-gall inks, based on the ratios of various elements relative to iron.
  • Complementary techniques such as Raman spectroscopy, FTIR, ASAP-MS can then be used, depending on the objectives of the analysis.
  • Infrared reflectography (IRR) can be used to confirm the presence of carbon.