Archaeometric characterization of pigments and mortars from Gothic wall paintings (13-15th Centuries)

A novel investigation on samples of gothic wall paintings (13-15th Centuries) has been carried out. They were found in some Churchs of Slovenia, being not yet studied using technics of materials analysis. One of them is selected: the Church of Anunciacion de Maria, city of Crngrob, Slovenia. The scientific investigation of the Gothic wall painting samples was mainly based in the preparation of the so-called stratigraphic sections (cross-sections) from the original small samples. This procedure allows to study the different layers of mortar as support and the painting itself. Next, these preparations were examined using several instrumental techniques commonly applied in materials characterization at the ICMSE, for instance, digital photography, optical and electronic microscopies, IR spectroscopy and EDX for chemical analysis. Aditional information concerning pigments and mortars was obtained by IR transmision spectroscopy using KBr pellets, as well as using XRD. Samples studied at the ICMSE can be classified in two groups, which allows to appreciate two procedures or techniques of wall paintings performed at the Church of Crngrob. The first is typical of Gothic Italian paintings: technic of so-called fresco buono over several layers of mortars, using marble powder to get a white and smooth surface. The results of the present study have also allowed to characterize and identify the inorganic pigments and mortars used in these wall paintings. They were found to be the appropiate for this kind of technical work. For instance, they have been applied iron oxides to get the yellow, orange and even green colours, but surprisingly it has not been found neither malachite (copper pigment of green colour) nor copper compounds to get a green colour. In older layers of wall paintings, the pigment cinnabar was used to get the red colour. It is a mineral used typically in Italy. As revealed in this research, no aglutinant except the lime coming from the mortar as support were used in these Gothic wall paintings. Moreover, this feature, besides of cinnabar application, allows to establish the 1400-1410 wall paintings in the artistic Italian current named Trecento. The second procedure to paint is a typical of North Europe: one or two layer of mortar with a fine layer of lime. This is used to improve the strenght of lime as an aglutinant in the mortar. With this study, it is concluded that the Italian and North-European artistic currents met in Slovenian territory, which is appraisable as much stilistic (Art History) as scientific (Chemical and Physical analysis) point of views. This kind of investigation allows to know better the Central European Art and the Slovenian Art in the Adriatic zone, as well as the general map of European Art in the Middle Age.