PLASTER AND MORTAR RADIOCARBON DATING OF NABATEAN AND ISLAMIC STRUCTURES,SOUTH JORDAN*

The study aims to use lime mortars and plasters to radiocarbon date Nabatean and Islamic structures from Petra and Udruh, south Jordan. Fifteen samples from seven structures were characterized by thin‐section, scanning electron and cathodoluminescence microscopy. The lime binders of all the samples and the organic inclusions from nine samples were AMS radiocarbon dated. The dates and the historical data of the samples were compared with each other. The results showed an agreement between the radiocarbon dates of the lime binders and the organic inclusions and the historical data for most of the samples. The radiocarbon dates of the lime binders supported by the radiocarbon dates of the organic inclusions and the archaeological data were helpful in reconstructing a rather precise chronology of the studied structures.     

The Temple of Venus (Pompeii): a study of the pigments and painting techniques

We report here on a study of 57 fragments of wall painting excavated from the Temple of Venus (Pompeii). These samples were characterised by a wide range of analytical methods. Data showed that the palette is varied, although not so broad as that found in other buildings in Pompeii, and is consistent with pigments used elsewhere in Pompeii and in the Roman Empire. It is composed of: natural earths, minerals and rare artificial pigments. Paintings are made up of thin paint layers (0.01–0.10 mm thick) strongly adhering to the underlying preparation layer. Nonetheless, in some cases thicker layers (up to 0.40 mm) were recognised, often spread on other previous painting layers. Samples were also compared with the microstratigraphic criteria developed in Piovesan (2009) to distinguish wall painting techniques. This comparison demonstrated that both fresco and lime painting techniques were adopted.     

Santa Maria di Collemaggio Church (L’Aquila,Italy): Historical Reconstruction by Non-Destructive Testing Techniques

The main goal of this work was the non-destructive testing (NDT) of an ancient fresco (15th century) preserved in the Santa Maria di Collemaggio Church (L’Aquila, Italy) and damaged after the 2009 earthquake. Active infrared thermography (IRT), near-infrared (NIR) reflectography and ultraviolet imaging (UV) were used. In addition, the state of the fresco prior to the earthquake was analyzed by electronic speckle pattern interferometry (ESPI), digital speckle correlation (DSC), raking light, tap, and chemical NDT techniques. The use of these techniques was important for the monitoring of new damages and for a comparison between the results over the years. Square heating thermography (SHT) data were processed using principal component thermography (PCT) and pulsed phase thermography (PPT) algorithms, in order to improve the defects’ signature and to reduce the impact of non-uniform heating and emissivity variations due to the painting’s pigments. A multi-analysis approach, segmentation operators and a specific data correlation method emphasize the overall study of the fresco. Furthermore, the facade and the high altar area were inspected by passive thermography and ground-penetrating radar (GPR), respectively. In the present case, the combined use of NDT techniques was useful to fill in the gaps in the construction history of the building.     

ANALYSIS OF NASRID POLYCHROME CARPENTRY AT THE HALL OF THE MEXUAR PALACE,ALHAMBRA COMPLEX (GRANADA,SPAIN), COMBINING MICROSCOPIC,CHROMATOGRAPHIC AND SPECTROSCOPIC METHODS*†

The pigments, binders and execution techniques used by the Nasrids (1238–1492) to polychrome carpentry in the Hall of the Mexuar Palace at the Alhambra (Granada, Spain) were studied using optical microscopy, scanning electron microscopy with EDX analysis, selective staining techniques and gas chromatography – mass spectrometry. This pioneering investigation presents the first results of a research project devoted to filling gaps in the knowledge of Nasrid art, traditionally approached by stylistic studies. Moreover, it is essential for the polychromy conservation of the studied artworks, and will help to clarify historical and painting uncertainties in the Alhambra monument. The palette consists of a limited range of colours: white (lead‐base pigment), red (cinnabar and red lead), blue (lapis lazuli), black (carbon‐based) and false gold (golden tin). Tempera grassa was the painting technique identified. Two types of grounds were used: (i) gypsum in calligraphy decoration for the false gold technique, and (ii) synthetic minium in geometric drawings in carpentry. Organic insulating layers of linseed oil were used between paint strata. Artists applied synthetic minium to protect the wood (Juglans regia and conifer) against attack by xylophages. To lighten the surface darkened by this ground layer, powdered tin was added to achieve a metallic lustre.     

A Quasi Non‐destructive Microsampling Technique for the Analysis of Intact Glass Objects By Sem/edxa

A novel sampling technique for the analysis of glass is described, which involves the removal of minute particles from an object with a diamond‐coated file, followed by energy‐dispersive X‐ray analysis in the scanning electron microscope (SEM/EDXA). The particles are fixed to adhesive carbon discs and carbon coated without grinding or polishing. Mean compositions are determined for 10 arbitrarily selected particles above a minimum grain size of 150 mm and normalized to totals of 100%. Tests were carried out on two standard soda–lime–silica glasses of well‐characterized composition, using two files of different grade. The analyses showed good agreement with the accepted values of all elements. Although the precision is somewhat reduced, this highly portable and quasi non‐destructive microsampling procedure provides almost the same information as that gained from samples embedded and polished in the normal way. Its application is thought to be especially useful for the investigation of intact glass objects and ceramic glazes.     

X‐ray Diffraction and SEM Investigation of Wall Paintings Found in the Roman Temple Complex at Horvat Omrit,Israel

In the present study, the fragments of wall painting found in the Roman Temple Complex at Horvat Omrit were analysed for the first time using the non‐destructive techniques of X‐ray diffraction (XRD) and scanning electron microscopy (ESEM) equipped with energy‐dispersive X‐ray spectroscopy (EDS). The application of these methods enabled unambiguous identifications of the pigments and plaster components of the samples. Quantitative information on mineral composition, crystallite size and elemental composition of each studied paint layer and plaster was collected. Based on the results of the XRD and EDS analyses, the green pigment was identified as celadonite. It was revealed that the Egyptian blue pigment does not contain impurities of tin and lead, and this excludes the use of bronze scrap in its synthesis. Comparison of the mineral composition of the paint layers indicates that a wider palette of colours was obtained by mixing the available mineral pigments. The study of cross‐sections of painted specimens revealed the usage of slaked lime for plastering. The obtained results give a new insight into the wall painting technique employed by ancient artists at Horvat Omrit, in northern Israel.     

CHEMICAL AND MINERALOGICAL ANALYSES OF GALLO-ROMAN WALL PAINTING FROM DIETIKON,SWITZERLAND

Around 90 samples of Roman wall painting dating from the first to the third century AD were analysed using different analytical techniques: X-ray diffraction, X-ray fluorescence, infrared spectrometry, scanning electron microscopy, energy dispersive spectrometry, optical microscopy and physico-chemical tests. The identified pigments are: ash, calcite, carbon black, celadonite, cinnabar, Egyptian Blue, glauconite, goethite, hematite and red lead. Pigment mixtures were used to get other colours such as brown, pink or purple. Three types of plaster were used: a first, and most dominant, with river sand, a second with crushed tile for damp places and a third, to which cinnabar was exclusively applied, was prepared with crushed calcite crystals.     

MATERIAL CHARACTERIZATION OF CERAMIC TILE MOSAIC FROM TWO 17TH‐CENTURY ISLAMIC MONUMENTS IN NORTHERN INDIA

Coloured tiles from two northern Indian monuments were analysed for their body and glaze composition. The results suggest that three different groups of tiles were used, all comprising a stonepaste body with alkali glaze. One group has strong similarities to a major Indian glass group, known as high alumina mineral natron glass, while the other two are similar to Western and Central Asian plant ash glazes, although with much lower lime content. The colorants conform with those usually employed in pre‐modern glazes, with lead‐tin yellow Type I and Type II for opaque yellow, copper blue‐turquoise, cobalt blue, manganese purple, and green through mixing of lead‐tin yellow and copper blue.     

Advances in Polychrome Ceramics in the Islamic World of the 12th Century AD

As part of a multidisciplinary programme of research on Islamic glazed pottery, the development of polychrome decoration during the 12th century AD has been investigated by examining polished sections through glazed pottery in an analytical scanning electron microscope. The two main decorative techniques used were underglaze and overglaze painting. The results suggest that true underglaze decoration, involving the application of pigment without any associated slip, was first developed in Syria, from where it spread to Iran, on to China and ultimately across wide areas of the world. In contrast, the overglaze technique used on mina'i ware was both very short‐lived and confined to Iran. The analytical results suggest that the probable explanation for this was the technical problems associated with maturing the overglaze paint and the consequent risk of unsatisfactory products.     

The Byzantine wall paintings from the Protaton Church on Mount Athos,Greece: tradition and science

The present work is a study of the wall painting complex in the Protaton Church (1295) on Mount Athos, Greece. These paintings, high in artistic value, are themselves a monument—representative of the Macedonian iconographic style. What follows is historic data set against the results of analytical investigations: the fruit of extensive research aimed at determining precise details about the applied painting techniques for the wall paintings. Hitherto it has been held that what was traditionally defined as “Byzantine fresco” was executed only on wet plaster with limewater as the sole binding medium. Now, however, through the application of instrumental analytical investigations, it is possible to demonstrate that a mixed technique involving both al fresco and al secco was employed. Furthermore, it was determined, on the basis of results from gas chromatography–mass spectrometry (GC/MS), that egg together with a modest amount of animal glue were the organic binding media used for the Protaton art work. It is certain that the scenes were initially begun on wet plaster. During or even after drying the painting was completed using the aforementioned protein binding media, thanks to which a more resistant cohesion to the painted layers was secured.     

CHARACTERIZATION AND PROVENANCE OF LATE ANTIQUE WINDOW GLASS FROM THE PETRA CHURCH IN JORDAN*

Fifth‐ to seventh‐century window glass fragments from the Petra Church in Jordan were analysed by EPMA and spectrophotometry to characterize their optical properties and chemical composition. The objective of this study was to determine the provenance of the raw glass and the secondary production procedures of the window‐panes. Judging from the material evidence, both the crown window‐panes and possibly the rectangular samples were produced through glass‐blowing techniques. The chemical data show that the assemblage forms a homogeneous group of soda–lime–silica glass of the Levantine I type. The green glass, however, has higher silica and lower soda contents than the aqua‐blue fragments. The composition of one sample suggested the recycling of Roman glass. Our results confirm the trade of glass between the Levantine coast and Petra during Late Antiquity. No colouring agents other than iron were detected. Spectrophotometry confirmed the presence of iron and showed that the window fragments absorbed light relatively equally across the visible part of the spectrum. The windows thus seem to have provided an almost colourless illumination for the sacred interior.     

Technology Transfer at the Periphery of the Mycenaean World: The Cases of Mycenaean Pottery Found in Central Macedonia (Greece) and the Plain of Sybaris (Italy)*

The study of technology transfer in pottery production to the periphery of the Mycenaean world has been addressed by considering two different areas, southern Italy and central Macedonia. Technological features such as ceramic paste, decoration and firing have been determined for different ceramic groups established according to provenance criteria. The studies of technology and provenance have been performed following an archaeometric approach, using neutron activation analysis, petrographic analysis, X‐ray diffraction and scanning electron microscopy. The results have revealed the existence of two different models. On the one hand, southern Italy seems to exhibit a more organized pottery production, which follows a Mycenaean‐like technology, while in central Macedonia production is probably more varied, being based in part on the technology of the local tradition.     

On the Metal‐Leaf Decorations of Post‐Byzantine Greek Icons

Metal leaves were widely used as decorative materials in post‐Byzantine ritual painting. Fifty‐two icons (mid‐15th to mid‐19th centuries) were studied by means of analytical techniques in order to reveal the materials and techniques encountered in their metal‐leaf decorations. High‐purity gold leaf was used throughout the studied period. Silver was employed rarely and mostly during the latter part of the period in consideration, while metal powders were mostly used from the mid‐18th century onwards. The identification of a gold–silver powder mixture and an ‘electrum’‐type alloy are among the reported findings, which are novel for post‐Byzantine icons. Three micromorphologically distinct highlighting techniques were also documented.     

AN ASSESSMENT OF COMPOSITIONAL AND MORPHOLOGICAL CHANGES IN MODEL ARCHAEOLOGICAL GLASSES IN AN ACID BURIAL MATRIX

The degradation mechanisms of glass in a buried context result in surfaces that have been depleted in various elements. The stability of the glass is primarily affected by the burial environment and the glass composition. However, in all archaeological glasses, the corroded layer that is formed on the surface tends to be low in alkalis, high in silica and lacking in cohesion. The extent to which the material has degraded, along with the physical nature of the corrosion, has a profound effect upon a wide range of factors affecting the stability of artefacts, as well as the choice of conservation techniques to be employed. This study has a number of objectives: determination of the morphology of the surface of the leached layer in glasses of two different compositions with different surface finishes; examination of the transition between the corroded material and the unaffected substrate; and investigation of concentration profile of different elements within the surface layers, as a function of depth. The study uses two glasses, fabricated under laboratory conditions, to replicate two common glass types found in the historical environment; a soda–lime–silica glass typical of those found in the Roman period throughout the Mediterranean and northwestern Europe, and high‐lime–potash glasses typical of those of Western Europe in the late medieval period. Three different surfaces have been prepared to mimic alternative manufacturing techniques such as blown, cast and ground surfaces for each composition. The glasses have been corroded under controlled laboratory conditions to replicate the buried environment. Imaging and chemical information is obtained using SEM–EDX and morphological information using IFM to produce 3‐D mapping from topographical surfaces.     

DOMUS AUREA,THE ‘SALA DELLE MASCHERE’: CHEMICAL AND SPECTROSCOPIC INVESTIGATIONS ON THE FRESCO PAINTINGS

In this paper, data collected from the wall fresco paintings of room 114, called the ‘Sala delle maschere’, of the Domus Aurea in Rome is analysed. The chemical composition of the efflorescence is investigated by infrared spectroscopy. The colour palette is determined by means of EDXRF, Raman spectroscopy and visible reflectance spectroscopy. EDXRF has allowed an extensive mapping of the elements present in the pigments and plaster; whilst in‐situ Raman spectroscopy has been determinant for attributing the molecular composition of the pigments in a number of doubtful cases. Most pigments identified are typical of Imperial Roman fresco paintings (first to fourth centuries AD) ( Ward‐Perkins 1981 ); more interestingly, we found evidence of fragments painted with Egyptian blue, which was normally used mostly in official rooms.     

水硬石灰作为贺兰口岩画加固材料的耐候性能研究

为了研究水硬性石灰在贺兰口地区的稳定性,以贺兰口岩石为试验对象,在实验室里分别用水硬性石灰和环氧树脂加固试块,并且做了耐冻融、耐热、耐高低温交变等一系列的耐候性能对比试验。结果表明,水硬性石灰与环氧树脂相比有较好的耐热性能;在冻融环境中,水硬石灰没有环氧树脂性能稳定,容易产生脱落现象。