Characterization of Seals from the Santi Quattro Coronati complex (Rome, Italy) with a focus on FTIR and chemometric...

Red wax seals were discovered at the Santi Quattro Coronati complex in Rome, within a staircase utilized as a domestic disposal pit in the late 15th or early 16th century. The four seals, recovered from three distinct stratigraphic units, were in a poor state of preservation. Over time, they underwent morphological and chemical transformations, resulting in the loss of the impressions they originally bore, along with the documents to which they were once affixed. The composition and manufacturing techniques of wax seals changed over time, resulting in complex, multi-component materials. A multi-analytical approach was employed to investigate their composition and conservation state, incorporating Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDS), X-ray Fluorescence (XRF) spectroscopy, Fiber Optic Reflectance Spectroscopy (FORS), Fourier-Transform Infrared spectroscopy (FTIR) in both micro-reflectance and Attenuated Total Reflectance (ATR) modes, and chemometric analysis. The study was exclusively performed on the archaeological samples recovered from the site under investigation. Consequently, the limited sample size precludes material classification as a primary objective. This study instead aims to advance knowledge of historical wax seal production materials and degradation processes, identifying key aging markers and assessing potential correlations between their conservation state and their respective stratigraphic contexts.