Stratigraphic EM-EDS, XRF, Raman and FT-IR analysis of multilayer paintings from the Main Altar of the St. James Church in Levoča (Slovakia)

A total of 25 inorganic (painting pigment and substrate) and organic components (binding and glaze) have been identified in the Main Altar of the St. James Church - the highest Gothic altar of the World. Micro-sampling of the first wood panel depicting Christ in the Garden of Gethsemane, the third one depicting Christ Crowned with Thorns and the fourth one named Ecce Homo was performed to reveal the stratigraphy of the color paintings. Chalk, cinnabar, lead-tin yellow, cerussite (lead white), malachite, azurite, an iron oxide, and fluorite have been identified using optical microscopy, X-ray fluorescence (XRF), scanning electron microscopy combined with energy-dispersive spectroscopy (SEM-EDS), Raman spectroscopy and Fourier-transform infrared spectroscopy (FT-IR). Green pigment consists of hydrous copper sulfates (probably posnjakite mixed with woodwardite) and carbonates represented by fragmental and spherulitic malachite. Infrared spectroscopy confirmed the linseed oil mixed with egg albumen as the main binding constituent of color paintings, whereas animal glue was used in ground layers. The red glazing consisted of krapplak dissolved in oil, whereas the green glaze was composed by Verdigris (copper acetate) dissolved in the Venetian turpentine. Some samples contained remnants of shellac. The composition of inorganic pigments, including the exotic deep-purple fluorite unknown in the central European realm, points to combined local and remote pigment sources, thus indicating flourishing trade connections within medieval Europe after cessation of Turkish invasions in the early 16th Century.