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Iordanidis A.,Technological Educational Institute of West Macedonia | Garcia-Guinea J.,CSIC - National Museum of Natural Sciences | Strati A.,16th Ephorate of Byzantine Antiquities | Gkimourtzina A.,16th Ephorate of Byzantine Antiquities
Analytical Letters | Year: 2014

The goal of this study was to characterize pigments used in the murals of two Byzantine churches, from Kastoria, northern Greece. The identification of the iconographer was also investigated by comparing the pigments applied in the wall paintings of the churches. Pigment microsamples of various colors were collected and analyzed by environmental scanning electron microscopy coupled with an energy dispersive system to characterize the elemental composition. Raman spectroscopy was employed to collect molecular spectra for characterization of mineralogical phases. Hematite, cinnabar, and minium were identified in red surfaces. Brown and yellow colors were assigned to mixtures of iron oxides, iron hydroxides, and calcite. Mixtures of iron, lead, and mercury compounds were used to produce different hues in the murals. Black tones were prepared primarily using charcoal and bone black. Grey colors were produced by a mixture of black carbon with calcite; blue hues, by a mixture of iron oxides, calcite, and black carbon. The minerals used were similar for both churches. However, the green color was prepared either by green earth or mixtures of iron oxides and calcite. A modern pigment, lithopone, was also determined, demonstrating restoration or overpainting and thus complicating possible correlations. Based on these preliminary results, the wall paintings could not be ascribed to a specific iconographer. © 2014, Copyright Taylor & Francis Group, LLC.


Garcia-Guinea J.,CSIC - National Museum of Natural Sciences | Strati A.,16th Ephorate of Byzantine Antiquities | Gkimourtzina A.,16th Ephorate of Byzantine Antiquities | Papoulidou A.,16th Ephorate of Byzantine Antiquities
Journal of Thermal Analysis and Calorimetry | Year: 2011

Several plaster samples were collected from the wall paintings of post-Byzantine monuments from Kastoria town, northern Greece. They were analysed mainly by simultaneous thermal analysis (TG-DTG/DTA) and X-ray diffraction and supplementary by electron microscope (ESEM-EDX) and Raman spectroscopy. Whitish and dark plaster layers were evident in most cases. Calcite, micas, and quartz were the dominant minerals, while dolomite, gypsum, and feldspar were detected as minor phases in most of the samples. Hydromagnesite and chlinochlore were also determined in a few samples. The utilisation of the results for chronological purposes (i.e. for assignment of different painting periods) was also suggested and the presence of dolomite and hydromagnesite could be characteristic for the provenance of the raw material. Gypsum was regarded mainly as a weathering product due to sulfation process, and secondly as a binding material of the plaster. The thermoanalytical results are in good agreement with the mineralogical data. The white plasters are categorized as hydraulic lime mortars, while the dark ones as natural pozzolanic mortars. Calcite and gypsum correlates well with their respective mass losses at certain temperature ranges and their Raman spectra are clearly detected. ESEM-EDX revealed fine calcareous components with aluminolisilicate aggregates and the application of the fresco technique either as a multi-layer or a single-layer plaster. The deterioration caused by salts (gypsum, halite, and nitratine) and micro-organisms was also determined. The detrimental effect of the salt crystallization and dissolution was also confirmed using the so-called Peltier-stage experiment. © 2010 Akadémiai Kiadó, Budapest, Hungary.


Iordanidis A.,Technological Educational Institute of West Macedonia | Garcia-Guinea J.,CSIC - National Museum of Natural Sciences | Strati A.,16th Ephorate of Byzantine Antiquities | Gkimourtzina A.,16th Ephorate of Byzantine Antiquities
Analytical Letters | Year: 2013

The investigation of gilded gold, black and red pigments from the Byzantine icon of Panagia from the church of Agioi Anargyroi Gymnasiou in Kastoria, northern Greece is the aim of this study. Small fragments, having a gold leaf finish, were detached from the icon and were analyzed by Environmental Scanning Electron Microscopy coupled to Energy Dispersive System (ESEM-EDS) and Raman microscopy. The chemical (EDS) composition of the gilding material revealed a high gold content alloy (Au 81.34 wt%) with trace amounts of silver (Ag 1.66 wt%), copper (Cu 0.62 wt%) and iron (Fe 0.58 wt%). The Raman spectrum of the gold leaf showed characteristic bands at 236, 369, and 468 cm-1. The red pigment on the surface comprises of Hg, S, and minor amounts of Pb and is attributed to the minerals cinnabar (HgS) and minium (Pb3O4). The black pigment has high carbon content, attributed to organic material (black carbon). The micro-Raman spectroscopy provided a more detailed determination of the composition of the red and black pigments. In particular, the vivid red color was attributed to cinnabar (bands at 253 and 342 cm-1). Particles of black carbon (bands at 1345 and 1577 cm-1) and oxalates (band at 861 cm-1) were determined on the black pigments. Dark regions on the pigmented surface were assigned to a mixture of cinnabar [bands at 253 and 342 cm-1] and minium [bands at 120, 142, 288, and 545 cm-1]. The latter lead oxides might have been used either as a dryer or a burnish agent for the gold leaf. The micro-structural and chemical analysis of several distinct strata of the icon, as observed under ESEM, revealed a red-colored stratum beneath the gold leaf, with an iron aluminosilicate composition. This is the so-called bole (red clay) commonly used as sub-strata for gilding art objects. Multiple layers of white ground material, composed of gesso (gypsum) underlie the bole strata. Moreover, one thin organic binder (animal glue) was is observed within the gesso ground of the icon. © 2013 Copyright Taylor and Francis Group, LLC.


Iordanidis A.,Technological Educational Institute of West Macedonia | Garcia-Guinea J.,CSIC - National Museum of Natural Sciences | Strati A.,16th Ephorate of Byzantine Antiquities | Gkimourtzina A.,16th Ephorate of Byzantine Antiquities | Papoulidou A.,16th Ephorate of Byzantine Antiquities
Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy | Year: 2011

This study concerns the investigation of pigments and efflorescence phenomena on the wall paintings of Kastoria, a rural, non-metropolitan Byzantine town. A large number of representative samples were collected from the murals of three churches, dated to post-Byzantine era (14th-17th c. AD). The identified pigments for the red colour were hematite (Fe2O3), cinnabar (HgS) and minium (Pb3O4), while brown and yellow colours were attributed to mixtures of ochres (Fe-oxides and hydroxides) and lime. The utilization of admixtures of iron, lead and mercury compounds was also attested in order to render specific tones on the painted surfaces. Black and dark blue hues were prepared using black carbon and Mn in some cases. Grey colours were assigned to a mixture of black carbon and lime. Green colour is rather attributed to admixtures of Fe-rich minerals and lime and not to the commonly used green earths. Baryte (BaSO4) was also evidenced as a filler or extender. Phosphorous was detected and connected to proteinaceous material and Mo and Sb were traced which are probably affiliated to Fe-oxides. Regarding efflorescing salts, the determined compounds are: calcite, dolomite, gypsum, halite, nitratine, natron and mirabilite, all of which are related to temperature and humidity changes and moisture fluctuations inside the wall paintings. © 2010 Elsevier B.V. All rights reserved.

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