A MULTI-ANALYTICAL APPROACH FOR THE CHARACTERIZATION OF POWDERS COMING FROM POMPEII ARCHAEOLOGICAL SITE

Nine black powders found in Pompeii houses in 3 different type of bronze vessels (cylindrical theca atramentaria, unguentaries and aryballoi) were characterized in order to assess a correspondence between the composition and the type of vessel and, possibly, to verify if these powders were inks or not. For the compositional characterization, a multi-analytical approach was adopted, which involved the use of scanning electron microscopy-energy dispersive X-ray (SEM-EDX), Fourier Transformed infrared spectroscopy (FTIR), Raman, X-Ray diffraction (XRD), electron paramagnetic resonance (EPR) spectroscopies, thermogravimetric analysis (TGA), gas chromatography coupled with mass spectrometry (GC/MS) and pyrolysis GC/MS (Py-GC/MS). Powders contained in cylindrical theca atramentaria form an homogeneous group, and their organic and inorganic compositions suggest that they were writing inks, while powders contained in unguentaries and aryballoi could have had several different uses, including writing inks and cosmetics. Furthermore, the composition profile of the powders found in cylindrical cases shows that at 79 A.D. in Pompeii archaeological site carbon-based inks were still used for writing, and iron-gall inks had not been introduced yet.