Characterization of residues found within some Roman unguentaria glass artefacts: preliminary results of a multi-disciplinary approach

Despite the large number of unguentaria vessels generally discovered in Roman archeological sites, very little information is available concerning the nature and chemical composition of the products that were originally contained within these artifacts. In this study a combined non-destructive approach that included Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy and X-ray fluorescence was used for the characterization of some brownish-black residues preserved in a series of glass unguentaria recovered from excavations at the Roman baths from Mălăiești. The obtained results highlighted the presence of different inorganic substances (an earth-based pigment rich in iron and manganese oxides, admixed with traces of lead- and mercury-based compounds) impregnated with an organic binder such as animal glue and possible natural essential oils, a powdered product associated most probably with a cosmetic/pharmacological use. The study allowed a first insight into the composition and origin of these ancient remains, providing important clues that may help to understand the original function of these unguentaria vessels.