The main churches of three monasteries in Thessalia, Central Greece, were decorated with wall paintings in the post-Byzantine period. The main goal of the present study is to characterize the inorganic and organic materials present in the paint layers of areas that have been gilded. Optical microscopic examination was carried out on samples taken from the gilded decoration of the paintings to view their layer build-up. The combined use of micro Fourier transform infrared (FT-IR) and micro-Raman spectroscopy led to the detection of the pigments and the binding media used. The results from specimens taken from different wall paintings were compared with each other to observe their differences and similarities. The three investigated churches are believed to have been painted by the same iconographer, Tzortzis, who however has only been identified in only one of them. The comparison led to the conclusion that there are many similarities in the painting materials used and the general methodology adopted and, therefore, this study offers support to the belief that the mural paintings of the three monasteries could have been painted by the same iconographer. While not authenticating the two painting as being by Tzortzis, the results provide further critical material that is consistent with this attribution. However, this statement must be carefully considered because the pigments identified have been commonly and diffusely used in historic mural paintings.
Keywords: Authentication; FT-IR; Fourier transform infrared spectroscopy; byzantine; raman spectroscopy; wall painting.