A STUDY OF CHINESE PORCELAIN RAW MATERIALS FOR DING,XING, GONGXIAN AND DEHUA WARES*

The raw material used largely determines the type and quality of porcelain produced. Twenty-three raw materials used for making Ding, Xing, Gongxian and Dehua porcelain bodies were studied using principal component analysis. Results show that for Dehua wares, only one raw material was used. For Ding wares, although there were many possible raw materials, the use of one alone is unlikely. Lingshan clay was the main raw material but it has to be mixed with other raw materials: Pinjiawa clay, quartz, feldspar and dolomite. The Xing pieces can be divided into three groups and Gongxian wares into two groups, which are discussed in detail.     

HISPANO-MORESQUE POTTERY PRODUCTION OF THE FOURTEENTH-CENTURY WORKSHOP OF TESTAR DEL MOLÍ (PATERNA,SPAIN)

Excavation of Testar del Molí, the only workshop found in the Manises-Paterna area, revealed the existence of a fourteenth-century ceramic workshop covering the remains of the thirteenth-century workshop. This study is concerned with the fourteenth-century production, and forthcoming papers will connect both epochs following the findings of current excavations. The chemical and mineralogical characterization of the ceramic production of this workshop shows the presence of three groups of ceramic pastes which could also be distinguished by, and, thus, related to, their daily use. The raw materials found in the excavation have also been mineralogically and chemically characterized, and a model of possible mixtures of raw materials has also been developed in order to determine their possible use in the manufacture of the pottery previously characterized.     

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.     

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.     

INVESTIGATING MATERIAL DECAY OF HISTORIC BUILDINGS USING VISUAL ANALYTICS WITH MULTI‐TEMPORAL INFRARED THERMOGRAPHIC DATA

This paper shows how visual analytics methodology can be used to facilitate interpretation of multi‐temporal thermographic imagery for the purpose of restoration of cultural heritage. We explore thermographic data in a visual environment from the unifying spatio‐temporal perspective in an attempt to identify spatial and spatio‐temporal patterns that could provide information about the structure and the level of decay of the material, and the presence of other physical phenomena in the wall. The approach is tested on a thermographic dataset captured on the façade of a Romanesque building from the 13th century—the Cathedral in Matera (Italy).     

RAW MATERIALS OF GLASS FROM AMARNA AND IMPLICATIONS FOR THE ORIGINS OF EGYPTIAN GLASS*

Analysis has been conducted on 19 blue glasses from Amarna in Middle Egypt dated to around 1350 BC. The results suggest that these glasses fall into two distinct types: cobalt coloured glasses with a natron based alkali made from local Egyptian materials, and copper coloured glasses with a plant ash alkali, which follow a Mesopotamian tradition of glass making. It is suggested that at least some of this copper/plant ash glass is imported into Egypt during the Amarna period despite extensive local production of cobalt/natron glass. Existing analyses (Lilyquist and Brill 1995) of the earliest glass from the reign of Tuthmosis III (c. 1450 BC) suggest that during this period the same two types of glass are present. Local Egyptian cobalt and natron in these early glasses implies that, despite the lack of archaeological evidence for production sites, glass was produced from its raw materials in Egypt as early as the reign of Tuthmosis III.     

MINERO‐PETROGRAPHIC STUDY OF COOKING WARE AND POMPEIAN RED WARE (ROSSO POMPEIANO) FROM CUMA (SOUTHERN ITALY)

Excavations carried out in Cuma by the Centre Jean Bérard archaeologists have uncovered a large quantity of pottery. This study is focused on cooking ware and on internal red‐slip cookware, also known as Pompeian Red Ware (Rosso Pompeiano), dated from the first century bc to the first century ad . A comparison with the minero‐petrographic composition of beach sands collected along the Bay of Naples coastline highlights the provenance of the temper from the Somma‐Vesuvius area, marked by leucite‐bearing scoriae and garnet. Petrochemical analyses allow us to distinguish two main groups of pottery characterized by different technological options based on the amount of temper and on the type of clay. X‐ray diffraction and scanning electron microscope data demonstrate improved accuracy in the production of Rosso Pompeiano, especially with regard to firing control, which was in a prevailing oxidizing atmosphere and in a narrow thermal range, between about 800 and 900°C.     

GLASS BY DESIGN? RAW MATERIALS,RECIPES AND COMPOSITIONAL DATA*

Compositional analyses of ancient and historic glasses have often been interpreted in terms of the use of specific raw materials in glass manufacture. However, the known inhomogeneity of many glass‐making raw materials and the insolubilities of some compounds make any explanation of compositional data problematic. This paper looks at three glass‐making alkalis with a view to understanding how the compositions of these raw materials are carried through to the final glass. The chemistry and variability of the raw materials are discussed, as is their contribution to the final glass composition. In addition, the choices and decisions made by glassmakers are acknowledged in the final glass compositions. This combination of factors addresses the complexity of predicting the use of specific raw materials from the finished glass composition.     

THE BRITISH ARCHAEOMAGNETIC CALIBRATION CURVE: AN OBJECTIVE TREATMENT

This paper examines the limitations and deficiencies of the current archaeomagnetic calibration curve in use in Britain and explores a different approach to its construction, drawing on recent advances in this subject, in particular the use of a weighted moving window method of averaging. The main advantage of this method is shown to be its ability to take into account uncertainties in both the magnetic direction and the archaeological date of data used in the calibration curve, leading to a secular variation curve with an associated error estimate. Hence, when dating a magnetic direction, the uncertainties in the calibration curve can be taken into account, as well as the uncertainties in the magnetic direction to be dated.     

ISOTOPES ON THE BEACH,PART 1: STRONTIUM ISOTOPE RATIOS AS A PROVENANCE INDICATOR FOR LIME RAW MATERIALS USED IN ROMAN GLASS‐MAKING

The provenancing of Roman natron glass is one of the most challenging problems in the field of archaeometry. Although the use of Sr and Nd isotope ratios and trace element signatures as an indication of provenance has proven promising, there are still many unknowns. In this study, the influence of the different raw materials on the final Sr isotopic composition of Roman natron glass is examined. It is shown that the ⁸⁷Sr/⁸⁶Sr ratio in natron glass is significantly influenced by the silicate fraction of the sand used and does not always provide a clear indication of the lime source used.