Physico‐Chemical Characterization of Pigments and Binders of Murals in a Church in Ethiopia

Here, we report the physico‐chemical characterization of wall paintings from the Petros and Paulos church in Ethiopia. This work represents the first technical study of paintings located in Ethiopia, rather than paintings in museum collections outside the country, using diverse analytical techniques. In situ examination with a portable X‐ray fluorescence spectrometer (pXRF) was followed by analysis of samples using optical microscopy (OM), scanning electron microscopy coupled with energy‐dispersive X‐ray spectroscopy (SEM/EDS), micro‐Raman spectroscopy (MRS), attenuated total reflection – Fourier transform infrared spectroscopy (ATR‐FT–IR), X‐ray powder diffraction (XRD) and pyrolysis gas chromatography – mass spectrometry (Py‐GC/MS). The paint stratigraphy, the compositions of the support material, the preparatory and painting layers were studied, as well as the morphology of the pigment particles. The results revealed the use of earth pigments and carbon black. The preparatory layer was uncommon; composed of dolomite, clay rich in clinochlore and sand, in contrast to the more common gypsum and calcite. The binder and the stratigraphic analyses suggested a distempera technique.     

The Structure and Chemical Composition of Wall Paintings From Islamic and Christian Times in the Seville Alcazar

Wall paintings from the Islamic epoch (10th to 12th centuries) and the Christian monarchy (14th to 16th centuries) have been recovered in discarded materials and on walls after reconstruction works in the Seville Alcazar. These paintings have spent centuries underground or under a plaster coat. Portable X‐ray fluorescence (XRF) and combined XRF/X‐ray diffraction (XRD) were employed in situ, as well as scanning electron microscopy (SEM–EDX), grazing angle incidence XRD and micro‐Raman spectroscopy, on cross‐section samples to fully characterize the materials in the wall paintings. Using these methods, the fresco technique was demonstrated, and many kinds of pigments were identified in accordance with the various periods of the history of the Alcazar, thus assessing the authenticity of all the wall paintings studied here.     

THE CHARACTERIZATION OF PAINTS AND WATERPROOFING MATERIALS FROM THE SHIPWRECKS FOUND AT THE ARCHAEOLOGICAL SITE OF THE ETRUSCAN AND ROMAN HARBOUR OF PISA (ITALY)*

This work presents the results of a diagnostic survey on the shipwrecks from the archaeological site of the ancient harbour of San Rossore (Pisa, Italy). The original waterproofing, caulking and painting materials were characterized by Fourier transform infrared spectroscopy (FTIR), gas chromatography – mass spectrometry (GC–MS), energy‐dispersive X‐ray microanalysis (EDX) and X‐ray diffraction (XRD). The major constituents of the waterproofing and caulking materials detected on the planks were tricyclic abietanes showing a high degree of aromatization. These compounds are indicative of a pitch obtained from the wood of trees of the Pinaceae family. The analysis of the organic components of the paint samples revealed diterpenoid acids characteristic of Pinaceae resins together with linear long‐chain alcohols and fatty acids, highlighting the presence of beeswax. Noticeably, the characteristic odd carbon number alkanes that are normally present in beeswax were not detected. The EDX and XRD analyses showed that hematite, calcite, cerussite and kaolinite were employed as pigments to paint the ships’ hulls.     

The Tomb of the Three Brothers in Palmyra: The Use of Mimetite,A Rare Yellow Pigment,in A Rich Decoration

The wall paintings of the Tomb of the Three Brothers in Palmyra display a very rich Greco‐Roman iconography. The study of the painting reveals the use of a great variety of pigments, including Egyptian blue and an extremely rare bright yellow pigment, mimetite, of which no other traces are known for this period. This pigment was identified through the combined use of two methods of analysis, scanning electron microscopy associated with X‐ray microanalysis (SEM–EDS) and X‐ray micro‐diffraction (XRD). The varied chromatic palette used underlines the refinement and the particular care given to these decorations. Notable differences have been found between the pigments of the decorations of the arch and those used for the rest of the chamber.     

A MULTI‐ANALYTICAL APPROACH FOR THE CHARACTERIZATION OF COMMODITIES IN A CERAMIC JAR FROM ANTINOE (EGYPT)*

This paper describes a multi‐analytical chemical study performed on the original, almost totally conserved, content of a small ceramic jar from the Antinoe archaeological site (fifth to seventh centuries ad, Roman Egypt) and now belonging to the archaeological collection of the Istituto Papirologico ‘Girolamo Vitelli’ (Florence, Italy). Scanning electron microscopy with an energy‐dispersive X‐ray spectrometer (SEM–EDX), Fourier transformed infrared spectroscopy (FTIR) and X‐ray diffraction (XRD) were all used to characterize the inorganic components of the archaeological material. The organic substances were analysed using FTIR, direct exposure mass spectrometry (DE–MS) and gas chromatography – mass spectrometry (GC–MS). The inorganic component essentially consisted of halite (NaCl). Among the NaCl crystals, lamellar elements were identified. They were chemically characterized by carbonato‐apatite and showed a concentric morphology typical of the scales of small fish. The most prevalent organic constituents of the sample were monocarboxylic acids, α,ω‐dicarboxylic acids, and cholesterol and its oxidation products. The organic material composition was consistent with the occurrence of lipids of animal origin. In addition, diterpenes related to pine pitch were also identified. The overall results suggest that the material recovered in the small ceramic jar found in Antinoe is a residue of fish‐based pickles such as garum, muria, allex and liquamen, which were commonly used in Roman times.     

The crystallinity of ancient bone and dentine: new insights by transmission electron microscopy

We studied various archaeological and palaeontological bones and dentines from different burial environments by Fourier transform infrared spectroscopy (FT–IR), X–ray diffraction (XRD) and transmission electron microscopy (TEM), in the framework of a general study of diagenesis. FT–IR and XRD were used to evaluate the global preservation state of the bone and dentine mineral phase by determining a splitting factor (SF) or a crystallinity index (CI), respectively. These data can be combined with studies on the nanometer scale made with TEM. This latter technique,coupled with electron microdiffraction, provides determination of dimensions and shapes of individual bone and dentine apatite nanocrystals as well as of secondary minerals formed during diagenesis. It enables us to distinguish between heat–induced recrystallization processes and crystal growth in solution occurring during diagenesis.     

DETERMINATION OF PIGMENTS AND BINDERS IN POMPEIAN WALL PAINTINGS USING SYNCHROTRON RADIATION – HIGH‐RESOLUTION X‐RAY POWDER DIFFRACTION AND CONVENTIONAL SPECTROSCOPY – CHROMATOGRAPHY

The employment of synchrotron techniques complemented by conventional laboratory systems has allowed us to deepen and improve our knowledge of Roman wall painting procedures. The palette identified in wall paintings from Pompeii and Herculaneum from the second century bc includes goethite, hematite, cinnabar, glauconite, Egyptian blue, and other components such as calcite and aragonite. Proof of the use of organic binders is provided by FTIR and PY–GC/MS. Therefore, the possibility of the use of ‘a secco’ techniques cannot be ruled out. Pigments in wall paintings are usually found in small percentages and conventional X‐ray diffractometers do not detect them. Synchrotron radiation – high‐resolution X‐ray powder diffraction has allowed identification with only a few micrograms of sample.     

MINERALOGY OF BOHEMIAN GREEN EARTH PIGMENT AND ITS MICROANALYTICAL EVIDENCE IN HISTORICAL PAINTINGS

While the most famous historical green earth deposits in Italy and Cyprus were exceptionally rich in celadonite, the deposits near Kadaň, Czech Republic, consisted of thin Fe‐rich celadonite impregnations accompanied by interstratified celadonite/smectite. In superimposed tuffs, smectites become prevalent and their colour changes from forest to olive green. Powder X‐ray microdiffraction and infrared microspectroscopy permit us to distinguish between green earth minerals in microsamples taken from works of art. The Ti contents and the Fe/Mg ratios help to indicate the presence of Bohemian green earth from Kadaň. We found this material in local 18th‐century works of art and also in paintings by Anton Kern (1709–47).     

LA VIE SOCIALE DE L'ART MOBILIER PALÉOLITHIQUE. MANIPULATION, TRANSPORT, SUSPENSION DES OBJETS ON OS, BOIS DE CERVIDÉS, IVOIRE

Summary: It has been suggested that some Palaeolithic objects show traces of long-term handling, suspension or transport. However, no criteria have been established for identifying such traces and differentiating them from other traces of natural or human origin. Handling, suspension, polishing with skin and transport of bone, antler and ivory objects have been reproduced experimentally and observed by optical microscopy and SEM. the width of striations seems to be the only criterion for differentiating handling, suspension and polishing. the transport of a single bone object in a leather bag produces striations of different dimensions to those produced by handling. the differentiation between traces of transport and those due to polishing with skin are more problematic. the transport of several bone objects in the same bag results in traces that differ according to the morphology and the hardness of the objects accompanying them. In particular, the pits generated by knocking against each other enable one to identify the nature of the other objects. Finally, analyses of bone objects known to have been subjected to long-term handling and archaeological objects dating from the Solutrean and Magdalenian cultures were compared with the experimental results.     

Problems of Analysis by FTIR of Calcium Sulphate–Based Preparatory Layers: The Case of a Group of 16th‐Century Portuguese Paintings

This paper provides a contribution to FTIR analysis of calcium sulphate‐based grounds of paintings when a mixture of compounds with different degrees of hydration is present. The study is based on the analysis with that technique, electron microscopy coupled with energy‐dispersive X‐ray spectrometry and X‐ray diffraction of both the grounds of 16th‐century Portuguese paintings and reference samples prepared with anhydrite and calcium sulphate dihydrate bound in an animal glue solution. It is shown that the interpretation of the degree of hydration of calcium sulphate ground samples using FTIR cannot be based solely on the study of the hydroxyl bands, as is usual in routine work, but that small deviations of the S–O vibration bands are an important indicator of the presence of anhydrite in the grounds.     

CHARACTERIZATION OF ARCHAEOLOGICAL AND IN SITU SCOTTISH WINDOW GLASS

Scottish window glass from both archaeological sites and historic buildings was examined using portable X‐ray fluorescence (pXRF) and scanning electron microscopy – energy‐dispersive X‐ray micro‐analysis (SEM–EDX). The elemental composition of the glass provides information regarding the materials used and, subsequently, an approximate range of dates of manufacture. pXRF is shown to be more vulnerable than SEM–EDX to the effects of surface corrosion and matrix effects in archaeological samples. The study showed that the production of window glass in Scotland from the 17th century onwards appears to closely parallel that in England. It also demonstrated the potential of pXRF for in situ studies of window glass in historic buildings. pXRF was used to assess two Scottish buildings; one in state care and one in private ownership. The building in state care, the Abbot's House at Arbroath Abbey, showed a uniform glass type, suggesting that the building was re‐glazed completely at some point during the late 19th or early 20th century. The building in private ownership, Traquair House, had a range of glass types and ages, demonstrating a different maintenance and repair regime. This type of data can be useful in understanding historic buildings in the future, particularly if re‐glazing is being considered.     

GEOCHEMICAL AND ENGINEERING GEOLOGICAL PROPERTIES OF THE VOLCANIC TUFFS USED IN THE ETRUSCAN TOMBS OF NORCHIA (NORTHERN LATIUM,ITALY) AND A STUDY OF THE FACTORS RESPONSIBLE FOR THEIR RAPID SURFACE AND STRUCTURAL DECAY

The geochemical and engineering geological properties of the tuffs used in the rock‐cut cliff tombs of the Etruscan necropolis of Norchia were investigated to evaluate their susceptibility to different weathering agents and confirm their origin. For the first time, materials were characterized by X‐ray powder diffraction (XRD), Fourier‐transform infrared spectroscopy (FT–IR), thermogravimetric analyses (TGA, DGA and DTG), scanning electron microscopy (SEM–EDS) and energy‐dispersive X‐ray fluorescence (ED–XRF), and their different origins confirmed. Tests of material properties indicate that both tuffs are poorly durable, but one of them is less susceptible to weathering. Although tombs made with the more resistant material show limited surface weathering, they undergo severe structural damage because of stress release and plant root infiltration. This, combined with the microclimatic conditions established inside river canyons, can trigger rock falls, leading ultimately to the complete destruction of these tombs.     

RELATIONSHIP BETWEEN THE COLORATION AND THE FIRING TECHNOLOGY USED TO PRODUCE SUSA GLAZED CERAMICS OF THE END OF THE NEOLITHIC PERIOD*

Ancient decorated potteries from Susa (Mesopotamia) dating from 4200 to 3700 bc , were studied in order to determine the origin and the nature of the raw materials used, and to identify the technological processes applied to make the ceramic bodies and their decorations. Bulk compositions were determined by particle induced X‐ray emission (PIXE), while the microstructure and the mineralogical phases were studied using scanning electron microscopy (SEM), energy dispersive X‐ray analyses (EDX) and X‐ray powder diffraction (XRD). The results showed that the raw materials used to elaborate these potteries were similar for all the ceramic bodies (carbonates and iron and magnesium‐rich clays containing sand), and for all the decorations (iron oxides, silica, potassic and alumina sources). The variations of coloration of the ceramics and of their decorations were due to different firing temperatures. The ranges of firing temperatures used by potters were evaluated on the basis of mineral stability domains.     

SCIENTIFIC INVESTIGATION OF FAIENCE FRAGMENTS ATTRIBUTED TO THE TOWN MOSAIC AT KNOSSOS*

We analysed a faience fragment from Bristol Museum and Art Gallery, to determine whether it belonged to the Town Mosaic, excavated at Knossos. Three Town Mosaic fragments from the Ashmolean Museum, Oxford were also examined. The objects were analysed using non‐destructive variable‐pressure scanning electron microscopy with energy‐dispersive X‐ray spectrometry. The Bristol object's composition and microstructures are similar to those of the Town Mosaic samples. Our results are also comparable to those from polished samples of Minoan faience (Tite et al. 2009 ), showing that VP SEM–EDX gives reliable results without invasive sampling. Silicaceous, copper‐rich microspheres were identified for the first time in two of the Ashmolean objects.     

Preliminary Characterization of Pottery by Cathodoluminescence and SEM–EDX Analyses: An Example from the Yeha Region (Ethiopia)

Yeha was a political and cultural centre of the Ethio‐Sabaean culture (D’MT) in northern Ethiopia and southern Eritrea. Part of the archaeological research deals with pottery of local, regional and imported origin. The research—investigations and examinations—tries to classify local pottery in two ways: first, by analysing the mineralogy of the temper using light microscopy and cathodoluminescence; and, second, by analysing the main element composition of the clay matrix using a scanning electron microscope with energy‐dispersive X‐ray detection (SEM–EDX). The cathodoluminescence shows that the temper material has differences in the colours of feldspars with a similar mineralogical composition. The results demonstrate that the pottery was produced by using local material that originates from various sources in the Yeha region and that the same raw materials were used in different types of pottery.     

Analysis of Heavy Metals in Smoke Deposits in the Limewash of the Royal Artillery Factory of Seville (17th Century): Contributions to the Location of the Furnaces

The Royal Artillery Factory of Seville in Spain originated from pre‐existing private bronze foundries dating from the 16th century. The paper analyses the stratigraphy of wall cladding in the areas traditionally known as the ‘Old Foundry’ and the ‘New Foundry’, through its characterization by optical microscopy, scanning electron microscopy with energy‐dispersive X‐ray spectrometry (SEM‐EDX), micro‐X‐ray fluorescence (μ‐XRF) and micro‐X‐ray diffraction (μ‐XRD), in order to analyse the metal deposits that have accumulated since the 17th century. The data obtained allowed the verification of the available historiographical information and the location of the original bronze smelting furnaces. The analysis of patinas deposited on the overlapping layers of lime also confirmed that neither the raw materials nor the composition of the alloys used presented any substantial changes.     

ANCIENT EGYPTIAN BLACK‐PATINATED COPPER ALLOYS*

This analytical study aims to investigate ancient Egyptian black‐patinated copper alloys. The study group was selected from the collections of the Egyptian Museum in Cairo and from the Faculty of Archaeology Museum in Cairo University. Examination and analysis were undertaken using optical microscopy (OM), scanning electron microscopy (SEM), energy‐dispersive spectroscopy (EDX), X‐ray diffractometry (XRD), X‐ray fluorescence analysis (XRF) and Fourier transform infrared spectroscopy (FTIR). The analysis results indicated that the black patina contained mainly tenorite (CuO). The study presents evidence of thermal patination and animal glue coating.     

A SPECTROSCOPIC INVESTIGATION OF PIGMENT AND CERAMIC SAMPLES FROM COPÁN,HONDURAS*

A combination of micro‐Raman spectroscopy, micro‐infrared spectroscopy and SEM–EDX was employed to characterize decorative pigments on Classic Maya ceramics from Copán, Honduras. Variation in red paint mixtures was correlated with changing ceramic types and improvements in process and firing techniques. We have confirmed the use of specular hematite on Coner ceramics by the difference in intensities of Raman bands. Different compositions of brown paint were correlated with imported and local wares. The carbon‐iron composition of the ceramic type, Surlo Brown, was confirmed. By combining micro‐Raman analysis with micro‐ATR infrared and SEM–EDX, we have achieved a more comprehensive characterization of the paint mixtures. These spectroscopic techniques can be used non‐destructively on raw samples as a rapid confirmation of ceramic type.     

Compositional Analysis by p‐XRF and SEM–EDX of Medieval Window Glass from Elgin Cathedral,Northern Scotland

Thirty shards of medieval window glass from Elgin Cathedral in north‐east Scotland have been subjected to compositional analysis by portable X‐ray fluorescence and scanning electron microscopy – energy‐dispersive X‐ray spectroscopy. Comparison with previous analytical studies suggests that the majority of the glass was probably produced in France, while a smaller group may have been made in Germany. Significant differences in base glass composition were observed between colours. Two distinct blue glasses compositions were identified. The composition of the grisaille paint differs from paint on the continent, providing the first evidence that it was made using local Scottish lead and iron pigments. This work represents the largest analytical study of Scottish medieval window glass yet undertaken and presents insights into the transfer of medieval materials, technologies and trade routes.     

GILDINGS AND FALSE GILDINGS OF THE BAROQUE AGE: CHARACTERIZATION AND CONSERVATION PROBLEMS

This work investigates the decayed decoration of the ‘Vergine del Carmelo’ chapel, with a particular interest in the residual gildings. Samples of the finishing layers were examined by VIS‐UV optical microscopy and scanning electron microscopy coupled with EDX spectrometry, in order to evaluate the unusual degradation phenomena. Mineralogical composition of the stucco substrate was characterized by X‐ray diffraction (XRD) and FTIR spectroscopy. The results showed the unexpected presence of a thick layer of brass flakes, applied without any binder, used as a substitute for the damaged original gold leaf, and highlighting a very uncommon selective corrosion process of the brass.