Micro-Raman spectroscopic investigation of external wall paintings from St. Dumitru’s Church, Suceava, Romania

Abstract

The external sixteenth century wall paintings of St. Dumitru's Church in Suceava (Romania) are suffering visually from deterioration. Fragments of these paintings spallated from the external wall have been studied by micro-Raman microscopy in order to elucidate possible causes of this process. Calcite and alpha-quartz are the components of the substratum indicating that the artists used the Roman fresco technique comprising a limewash putty. No organic binders have been detected in the substrate or pigment application. Amorphous carbon and goethite, alpha-FeOOH, have been identified in areas containing residues of grey and yellow pigments, respectively. Small amounts of gypsum have been detected in the grey areas which we attribute to special attention being given to surface preparation and pigment application in these areas. An abundance of sodium nitrate, nitratine, microcrystals have been observed on the surfaces of many fragments which suggests that a biodeterioration process originating from guano deposits could have been operating in these frescoes.

Raman spectroscopy of minerals and mineral pigments in archaeometry

“…Nevin et al performed an analysis of the paint samples from a 16th century wall painting in the church of Agios Sozomenos in Galata, Cyprus, and found hydrated copper oxalate, analogous to the naturally occurring blue–green mineral moolooite. The 16th century external wall paintings (fresco technique) of St Dumitru's Church in Suceava (Romania) were analysed by Hernanz et al, evidencing a degradation as a result of nitrogenous organic materials.…”

A detailed micro‐Raman spectroscopic study of wall paintings of the period AD 100–200: effect of atmospheric conditions on the alteration of samples

“…[33] Thirdly, in all studies of red ochers, Raman spectra of hematite show features at these two wavenumbers, thus attesting to the presence of intimate mixtures in natural hematite/magnetite earths. [24] It is known that with an increase in magnetite content, there is a shade shift from red to violet.…”

Scientific investigation of the Imperial Gates belonging to the wooden church from Săcel, Turda County, Romania

“…Synchrotron-based Imaging FTIR Spectroscopy has been used to evaluate paintings cross-sections [19]. Along with FTIR spectroscopy and micro-spectroscopy, other analytical methods (XRF [11], Raman spectroscopy [12], DSC, GC-MS [13]) are employed in the investigation and determination of wooden icons, pigments and external wall paintings, the authors of this manuscript having a solid background in the scientific investigation of artworks [11][12][13][14][15][16][17]. Other research groups use analytical techniques as Fluorescence microscopy [20][21][22], TG-DTG-DSC [23], and other spectroscopic techniques in order to investigate as well as authenticate the cultural heritage [24][25][26][27][28][29].…”

“…As concerning the painting layer, using FTIR spectroscopy one can establish the nature of the pigment. [11][12][13][14][15][16][17]. Wood analysis can be performed using FTIR spectroscopy, X-ray diffraction and DSC thermal analysis, each type of analysis offers information about the wood nature, crystalline-amorphous and lignin/cellulose ratios and of the conservation status (fungal attack, etc.…”