PIGMENT IDENTIFICATION IN GREEK POTTERY BY RAMAN MICROSPECTROSCOPY*

Raman microspectroscopy (RMS) is now established as a key technique for the identification of pigments of archaeological pottery that permits the in situ study of art objects by a non‐destructive procedure. The information obtained represents a great aid to restoration and conservation techniques. In this work, the chemical nature of the red, black and white pigments of five samples of Greek pottery from the end of the fifth century and the first half of the fourth century bc , exhumed from the Iberian necropolis of Cabezo Lucero (Guardamar del Segura, Alicante, Spain), has been identified. The black and the red pigments are found to be magnetite (Fe₃O₄) and hematite (α‐Fe₂O₃), respectively. The white pigment is found, for the first time, to be composed of alumina (α‐Al₂O₃ and γ‐Al₂O₃) probably yielded by the thermal decomposition of Greek bauxite.     

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.     

ANALYSIS OF ROMAN WALL PAINTINGS FROM THE THERMAE OF ‘IULIA CONCORDIA’

Twenty‐six wall painting fragments and some plaster, ‘intonachino’ and stucco samples, discovered at Iulia Concordia, have been studied by different analytical techniques to gain information about the pigment nature and the composition of the materials. The presence of calcite, dolomite and aragonite allow the distinction of four groups of wall samples varying in the nature of pigments and in the application technique. These differences can be attributed to different execution times or, more probably, to the arrangement of the rooms in the building structure. The nature of the pigments found in the Thermae of Iulia Concordia appears similar to that found in other Roman villas of Venetia et Histria, with the use of precious pigments such as Egyptian blue and cinnabar.     

NEW EVIDENCE FOR APULIAN RED‐FIGURE PRODUCTION CENTRES

A total of 52 South Italian red‐figure vases were subjected to neutron activation analysis. The primary aim of the study was to determine whether all Apulian red‐figure pottery datable to the period c. 430–340 bc was produced at the Greek colony of Taras, as has been widely assumed. Three chemically distinct compositional groups were isolated and compared to archaeological reference material from Taranto. The results of this comparison suggest that some Early Apulian red‐figure pottery may have been produced outside of Taras from the fifth century bc onwards.     

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.     

CHARACTERIZATION OF CORAL RED SLIPS ON GREEK ATTIC POTTERY*

Samples of red and black gloss from Greek Attic pottery of the late sixth to fifth centuries bc were examined using scanning electron microscopy (SEM and FIB/STEM). The focus of the study was the chemical and microstructural characterization of the red gloss that was first produced during this period. Two groupings of red gloss were revealed. One red was found to be compositionally similar to the black glosses (labelled ‘LCM coral red’). The other red showed more significant chemical differences, such as higher calcium and magnesium, in comparison to the black (labelled ‘HCM coral red’). The existence of two chemically distinct reds—otherwise identical in colour and texture—suggests that there was more than one source of clay available to the Attic potters for producing red.     

LEAD ISOTOPE ANALYSES OF BRONZE AGE COPPER‐BASE ARTEFACTS FROM AL‐MIDAMMAN,YEMEN: TOWARDS THE IDENTIFICATION OF AN INDIGENOUS METAL PRODUCTION AND EXCHANGE SYSTEM IN THE SOUTHERN RED SEA REGION*

The results of the lead isotope analysis (LIA) of 15 copper‐base artefacts from the Bronze Age site of al‐Midamman, Yemen, are reported. The LIA data suggest the existence of an indigenous Bronze Age metal production and exchange system centred on the southern Red Sea region, distinct from those in neighbouring regions of Arabia and the Levant. These preliminary results are highly significant for the archaeology of the region, suggesting that local prehistoric copper extraction sites have thus far gone unrecorded, and highlighting the need for systematic archaeometallurgical fieldwork programmes in the countries surrounding the southern Red Sea.     

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.     

UNIQUE PRE‐ROMANESQUE MURALS IN KOSTOĽANY POD TRÍBEČOM,SLOVAKIA: THE PAINTING TECHNIQUE AND CAUSES OF DAMAGE

Pre‐Romanesque murals at Kosto?any pod Tríbe?om, Slovakia, have been investigated by portable X‐ray fluorescence and by microanalytical methods to identify painting materials (pigments and binders), and to explain the degradation of colours. Today, missing green and blue shades have been reconstructed according to residual concentrations of Cu, which correspond to copper chlorides—products of salt corrosion of the copper carbonates azurite and/or malachite, accelerated by micro‐organisms. As confirmed by powder X‐ray microdiffraction, original minium (Pb₃O₄) has been transformed to brown–black plattnerite (PbO₂). In increased humidity, even insoluble pigments are washing down from the walls and the intensity of colours further diminishes.     

Raman Spectroscopic Analysis of Ancient Egyptian Pigments

The application of FT‐Raman spectroscopy and visible Raman microscopy to the non‐destructive analysis of pigment specimens excavated from Tell el Amarna by Flinders Petrie in the 1890s has provided information about the chemical composition of the materials used by XVIIIth Dynasty artists in the New Kingdom at the time of King Akhenaten, c. 1340 bc. Comparison of the Raman spectra of the samples labelled ‘red and yellow ochre’ with documented, archival material from geological collections provided a clear indication of the materials used in the iron(III) oxide/hydroxide system, including α‐hematite, goethite, maghemite, magnetite and lepidocrocite. The yellow–orange specimen labelled ‘realgar’ proved to be a mixture of realgar and pararealgar; since the specimen had been sheltered from light since its excavation, this could indicate that the ancient Egyptian artists recognized the colour variation and may have used this to effect in their decorations. A specimen of yellow ochre contained goethite, α‐FeO.OH, with particles of crystalline, highly ordered graphite; in contrast, the red ochre specimens contained amorphous carbon particles.