SEM-EDS and μ-Raman characterisation of the contents of the medieval inkwell of Palazzo Paradiso (Ferrara, Italy)

The application of geochemical analysis provides valuable insights into the characteristics of soil components associated with archaeological artefacts. Such analyses of archaeological soils yield essential information regarding past human settlements, their activities and the surrounding environment. This study focused on the investigation of the contents of an inkwell discovered in an ancient throwing basin during excavations at Palazzo Paradiso, Ferrara, in the early 1980s. These vessels, commonly used during the medieval period is considered to serve as reservoirs for ink utilized in manual writing on parchment or paper. The contents of the inkwell were analysed using scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS) and micro-Raman spectroscopy (μ-Raman) technique. SEM-EDS analysis revealed significant levels of sulphur and iron, while μ-Raman spectroscopy identified the presence of haematite (Fe2O3). These findings align with the observations of Chireceanu C. et al., 2015 [1] and confirm the presence of iron sulphate, a key component in ancient in ancient inks. Specifically, iron-gall ink (IGI) is an iron-polyphenol complex, was produced by reacting tannins extracted from gall nuts with the Fe2+ derived from iron sulphate. Gum arabic was employed as the organic binder, while ‘vitriol’ consisting of iron (II) sulphate, was mainly used as the iron salt facilitating the formation ofa black/dark precipitate essential for ink production.