The technological development of stonepaste ceramics from the Islamic Middle East

The microstructures and chemical compositions of stonepaste bodies from the Islamic Middle East, typically produced from a mixture of ten parts crushed quartz, one part crushed glass and one part white clay, are investigated using analytical scanning electron microscopy. For comparison, replicate stonepaste bodies are produced in the laboratory at firing temperatures in the range 900–1200 °C, and are similarly examined. The stonepaste bodies are divided into four primary microstructural groups that reflect the increasing reaction during firing of the glass fragments with the clay and quartz particles. The observed microstructures are then used to assess the geographical and chronological variations in the production technology of stonepaste ceramics from Egypt, Syria, Iran, Uzbekistan and Turkey, spanning the period from 11th to 17th centuries AD.     

AN INVESTIGATION INTO THE RELATIONSHIP BETWEEN THE RAW MATERIALS USED IN THE PRODUCTION OF CHINESE PORCELAIN AND STONEWARE BODIES AND THE RESULTING MICROSTRUCTURES*

The microstructures of porcelain and stoneware bodies from north and south China, spanning the period from the Tang to the Ming dynasty (7th–17th centuries ad ), were examined in polished sections in a scanning electron microscope (SEM) after etching the sections with hydrofluoric acid (HF). Mullite, present as fine, mainly elongated crystals, is the dominant crystalline phase observed. The bulk chemical compositions of the bodies are determined by energy‐dispersive spectrometry in the SEM, and the relative amounts of mullite and quartz present in the different ceramics are estimated from X‐ray diffraction measurements. Mullite formed from areas of kaolinitic clay, mica particles and feldspar particles is distinguished through a combination of the arrangement of the mullite crystals, and the associated SiO₂/Al₂O₃ wt% concentration ratios. It is shown that very different microstructures are observed in ceramic bodies produced using kaolinitic clay from north China (Ding porcelain and Jun stoneware), porcelain stone from south China (qingbai and underglaze blue porcelain and Longquan stoneware), and stoneware clays from south China (Yue and Guan stonewares). Therefore, SEM examination of HF‐etched, polished sections of the bodies of high‐refractory ceramics has considerable potential for investigating the raw materials used in their production.     

An archaeometric contribution to the characterization of Renaissance maiolica from Urbino and a comparison with coeval maiolica from Pesaro (the Marches,central Italy)

The results of an archaeometric trial study performed on an important finding of Renaissance maiolica (mid‐15th to early 16th century) from the Ducal Palace of Urbino are presented. Mineralogical–petrographic data (XRD, OP, SEM–EDS) and chemical characterization (ICP/AES–MS: major and trace elements) of both ceramic bodies and glazes were compared with similar data provided on coeval maiolica found in archaeological excavations in Pesaro, now stored in the city's Municipal Museum, in order to verify an origin of the potteries from common (Pesaro) or different (Pesaro and Urbino) production centres. The results indicate that ceramic bodies were produced with quite similar illitic–calcareous clays, most probably taken from the same local Pliocene Formation. Similarities were also found concerning the glaze's glass (silica–lead), colourants (cobalt, copper and manganese) and pigments (lead antimonate and cassiterite).     

The glass of Nogara (Verona): a “window” on production technology of mid-Medieval times in Northern Italy

The site of Nogara (province of Verona, Italy) provides valuable insights into the complexities of the glass industry in mid-Medieval times, due to its timing, which ranges mainly between the 10th and 11th centuries AD, and to the great quantity of glass findings, mainly tableware. In the present paper, the combination of archaeological, chemical and textural data allows us to identify production technologies in a time-interval perceived to be a period of technological transition for glass. In particular, the frequent occurrence of recycled natron glass and only a few glass samples made with soda plant ash indicate that recycling of earlier glass was common in inland Northern Italy in the 10th–11th centuries AD. In addition, blue and reticello decorations were obtained by recycling earlier glass mosaic tesserae, as shown by much Co, Cu, Sn, Sb and Pb and the presence of crystallised calcium antimonates. A few glass samples with chemical compositions intermediate between natron and soda plant ash glass were also identified, suggesting a gradual change in glass composition from natron-based towards soda ash-based production technology, which prevailed in the 13th-14th centuries. In conclusion, the difficulty in describing mid-Medieval glass as a well-defined entity, due to the great propensity for recycling earlier glass samples which causes variability in chemical compositions, particularly those of trace elements, is clearly documented here. In any case, this paper contributes to a new type of chrono-typological scanning and to more detailed knowledge of glass production technology during mid-Medieval times in Northern Italy, little found in the literature until now.     

French Decorative Ceramics Mass‐Produced During and After the 17th Century: Chemical Analyses of the Glazes

Chemical analyses of a group of Pb silicate–glazed decorative objets d'art showing scenes of the French royal family (Louis XIII and Henri IV), and biblical and classical figures, have been analysed and compared with other similar heritage ceramics and with the rustiques figulines of Bernard Palissy (1510–90) and his followers and imitators. In particular, non‐destructive ion‐beam chemical analyses (PIXE and PIGE) have been performed on 11 ceramic artefacts from the Cleveland Museum of Art (CMA) and a like number from several French museums; results for 13 objects are described in detail in this paper. SEM–EDX has been performed on chips (‘microsamples’) taken from small unobtrusive defective regions on the CMA ceramics. The results of the ion‐beam and SEM–EDX techniques are in good agreement. All the decorative ceramics included uniform non‐opacified glazes. None of these objects can be of 16th century production; all must date from the 17th to the 19th centuries.     

SIENESE ‘ARCHAIC’ MAJOLICA: A TECHNOLOGICAL STUDY OF CERAMIC BODIES AND COATINGS*

The aim of the present study is to reconstruct the production technology of Sienese ‘archaic’ majolica in the early decades of the 14th century ad . The integration of archaeological data with archived data revealed the presence of numerous workshops, suggesting that the Sienese tradition of majolica production was well developed up until the end of the 16th century. Sixty‐seven uncoated and coated waste products were analysed. The ceramic bodies were examined by OM, XRDp, SEM–EDS, XRF, ICP–OES, ICP–MS and INAA. The coatings (enamels and glazes) were analysed by SEM–EDS and Raman microspectroscopy. The results showed that ceramics were rejected due to poor control of the firing temperature (technological wastes), faulty production technology (wastes of uncertain classification) and accidents (post‐firing wastes). Finally, the analyses revealed extreme homogeneity of the ceramic bodies, indicating the continued use of the same raw material over the whole period studied.     

PRODUCTION TECHNOLOGY OF ROMAN LEAD‐GLAZED POTTERY AND ITS CONTINUANCE INTO LATE ANTIQUITY

A broad selection of Roman lead‐glazed pottery dating from the first century ad through the fifth century ad was studied to establish locations of workshops and to address their technology of production. The ceramic bodies were analysed by ICP–AES. In addition, lead isotope analysis was undertaken on a selection of glazes. These findings suggested that there were several regions responsible for the production of lead‐glazed ceramics in the western Roman world, including central Gaul, Italy and, probably, Serbia and Romania. Using the body compositions as a starting point, the glazing techniques employed by each of the potential workshops were examined using electron probe microanalysis. It was determined that there were two primary methods of glazing. The first method used lead oxide by itself applied to non‐calcareous clay bodies, and the second method used a lead oxide‐plus‐quartz mixture applied to calcareous clay bodies. Based on these data for clay composition and glazing method, transfer of technology from the Hellenistic east to the western Roman world was proposed. Likewise, the inheritance of lead‐glazing technology into late antiquity was established by making comparisons to lead‐glazed ceramics dating to the seventh to ninth centuries from Italy, the Byzantine world and Tang Dynasty China.     

Chemical analysis of white porcelains from the Ding Kiln site, Hebei Province, China

The Ding kilns were some of the most famous early kilns of medieval China, producing huge quantities of white and cream-white porcelains of outstanding technical and aesthetic quality. Since 1949 they have been excavated three times, in 1965, in 1987, and in 2009 respectively. In this latest study 69 white porcelain sherds from assured contexts and from the 2009 excavations were analyzed using laser ablation techniques (ICP-AES). The samples date from Five Dynasties, Northern Song and Jin Dynasties respectively (early 10^th to early 13^th C CE). The results show that Ding wares of different times show different characteristics that can be demonstrated through chemical composition. During the early phase of production the Ding ware bodies consisted largely of high firing kaolinitic clays with predominantly calcareous materials as fluxes. After the early Northern Song Dynasty, some calcareous material was replaced by a more potassic material. The compositions of the glazes show a parallel evolution to the bodies. However, because the glazes are very low in titania it seems unlikely that the main clay ingredients of the bodies could have been used in the glaze recipes. For much of the kiln site’s history the glazes appear to have been made mainly from the same siliceous flux-rich materials that had been blended with the main body-clays used to make the Ding ware porcelains, plus some extra calcareous material. The P₂O₅ contents of the glazes suggest that wood ash may have been one source of CaO in the glaze recipes.     

Compositional and Microstructural Study of KoryŎ Celadon and Whiteware Excavated from SŎRi Kiln in Kyŏnggi Province

An extensive study of the composition and microstructure of celadon and whiteware sherds excavated at Sori, one of the most important sites that were active during the founding stage of the stoneware and porcelain industry in Korea, was carried out. The analysed sherds were organized according to four different levels of the excavation and four different styles of haemurigup foot rim. Principal component analysis of the chemical compositions of the sherds revealed slight differences in their body and glaze compositions between the levels of excavation. Porcelain stone with high silica and low aluminium contents was generally used as the body material and wood ash as the chief flux in the glaze. Over the period of operation, the aluminium content in the bodies of the ceramics decreased and the P₂O₅ content in the glazes increased. Glazed bodies were fired in a single step, in contrast to the two‐step method used in later ceramic production. Firing conditions were adjusted to produce vitrification of the glazes, which meant that vitrification of the ceramic bodies occurred to varying extents, mostly determined by the relative contents of flux in the body and the glaze.     

Rice chaff in ceramics from the archaeological site of Sumhuram (Dhofar,Southern Oman)

The identification of the chaff used as temper in ancient ceramics represents a possible source of information about the area of origin of the pottery. This paper studies the occurrence of rice (Oryza sp.) chaff in potsherds from the archaeological site of Sumhuram (Dhofar, Sultanate of Oman). The information gathered at the site offers insight into commerce routes and networks to which the town belonged in the first centuries AD. The analysis of the plant material in the pottery and potsherds can also furnish interesting data on the ancient technologies of pottery production.     

THE EVOLUTION OF LUSTRE CERAMICS FROM MANISES (VALENCIA,SPAIN) BETWEEN THE 14TH AND 18TH CENTURIES

A set of 33 fragments of lustre‐decorated ceramics uncovered during an archaeological excavation in Manises (Valencia, Spain) have been studied. These ceramics were produced in Manises from the 14th to the 18th century. This well‐dated set of ceramic shards represents the diversity of Manises lustre production and is a complete time sequence of reference for the technological analysis. Texture analysis of the glazes has been carried out by SEM–EDAX, the inner and outer surfaces of the lustre decorations being analysed with non‐destructive ion beams by PIXE and RBS, and also by high‐resolution electron microscopy. The results are compared with other lustre productions and the time trend of the microstructures, glaze and lustre composition is analysed. It is concluded that Sn was used to opacify glazes until the beginning of the 17th century and that changes in the lustre microstructure occurred around ad 1500.     

INVESTIGATION ON ROMAN LEAD GLAZE FROM CANOSA: RESULTS OF CHEMICAL ANALYSES*

Five sherds of green glazed pottery excavated at Canosa (Apulia) in Italy have been analysed by scanning electron microscopy. The aim of the investigation was to determine the chemical composition of the glazes and thus obtain information on the methods used in their production. The glazes were all of the high‐lead type, coloured green by the addition of copper. Intermediate layers, observed at the interface between the glaze and body and giving the appearance of an applied white slip, were the result of the crystallization of lead feldspar from the molten glaze. Non‐calcareous clays were used in the production of the pottery bodies. Concentration profiles from the glaze exterior to the body suggested that the glazes were produced by applying a suspension consisting of lead oxide plus silica to the bodies. On the basis of the glaze and body compositions, it is suggested that the Canosa glazed pottery was produced locally.     

DISCOVERY,PRODUCTION AND USE OF TIN‐BASED OPACIFIERS IN GLASSES,ENAMELS AND GLAZES FROM THE LATE IRON AGE ONWARDS: A REASSESSMENT*

Tin‐based opacifiers (lead stannate yellow and tin oxide white) were first used in glass production for a short period in Europe from the second to the first centuries bc , and then again throughout the Roman and Byzantine Empires from the fourth century ad onwards. Tin oxide was also used in the production of Islamic opaque glazes from the ninth century ad , and subsequently in enamels applied to Islamic and Venetian glasses from the 12th century ad onwards. A selection of published analytical data for the tin‐opacified glasses, enamels and glazes is summarized, and the methods used in their production are reassessed. The phase transformations occurring when mixtures of lead oxide, tin oxide and silica are fired are investigated with high temperature X‐ray diffraction (XRD) using a synchrotron radiation source, and these results are used to explain the observed differences in the glass, enamel and glaze compositions. Possible reasons for the use of tin‐based opacifiers in the second to first centuries bc , and for the switch from antimony‐ to tin‐based opacifiers in the fourth century ad are suggested, and the possible contexts in which tin‐based opacifiers might have been discovered are considered. The introduction of tin‐opacified glazes by Islamic potters in the ninth century ad is discussed in terms of technological transfer or independent invention.     

Two unique Byzantine immured lead-glazed relief ceramic icons and related tiles from the church of St Basil in Arta,Greece: investigation and interpretation of materials and techniques

St Basil’s late Byzantine church in Arta (NW Greece) is unique among other surviving churches of the same era as a result of two glazed relief ceramic icons and arrays of square glazed tiles that decorate its external wall. The latter decorative items were carefully examined by means of analytical techniques in order to reveal the materials and techniques used for their manufacture and thus interpret their connection to the contemporary Byzantine and Italian ceramics. Analytical results indicate that lead plus quartz suspensions were employed for the fabrication of the majority of the glazes in the spirit of recipes for Italian Archaic majolica pottery, and thus they are differentiated from the common contemporary Byzantine products. Nonetheless, the raw materials used in the Arta area ceramics deviate substantially from those used in the Italian products and, possibly, a local (NW Greece) production is reflected. The unexpected rather rich variety of raw materials and/or techniques that underlies the visual uniformity of the glazed material in consideration might reflect selection of the best products generated upon experimentation with various contemporary technical alternatives. Finally, the decorative arrangement of the glazed items that we see today might reflect a way to circumventing original objections to the ceramic icon innovation.     

GLAZED CERAMIC MANUFACTURING IN SOUTHERN TUSCANY (ITALY): EVIDENCE OF TECHNOLOGICAL CONTINUITY THROUGHOUT THE MEDIEVAL PERIOD (10TH–14TH CENTURIES)*

Archaeometric investigation allowed the characterization of two important classes of ceramics: ‘vetrina sparsa’ and ‘invetriata grezza’. Their archaeological peculiarity makes them particularly suited for tracing the evolution of glaze manufacturing in southern Tuscany throughout the medieval period (10th–14th centuries). These ceramics were found in different sites of historical importance, and also from a mining perspective. Local copper, lead, zinc and iron mineralizations supported the growth of several settlements in the vicinity of the mines. The many castles and different archaeological finds (ceramics, glazed ceramic, slag etc.) attest to the intense mineral exploitation of the area from at least the first millennium bc up to the modern period. In light of these geological and archaeological characteristics, archaeometric investigation was intended to provide insight into ancient technical knowledge of ceramic glazing and to determine the source area for raw materials in the medieval period (10th–14th centuries). Ceramic bodies were analysed through OM, XRDp, SEM–EDS and XRF, while coatings were investigated through SEM–EDS. Mineralogical, petrographic and chemical analyses revealed slightly different preparation and firing processes for the two classes of ceramics. These data suggest the continuity through the centuries of the ‘vetrina sparsa’ and ‘invetriata grezza’ production technology. The mineralogical phases, such as monazite, xenotime, zircon, barite, Ti oxide, ilmenite, titanite, tourmaline and ilvaite, and the lithic (intrusive and volcanic) fragments detected within the ceramic bodies suggest a source area in the vicinity of the Campiglia mining district. Lastly, the presence of Cu–Zn–Pb (Ag) and Fe sulphide mineralizations (materials used to produce glaze) in the area supports the hypothesis of local manufacture.     

The use of radiocarbon-derived ΔC as a paleoclimate indicator: applications in the Lower Alentejo of Portugal

Values of δ¹³C are frequently reported with radiocarbon dates from organic materials. In C₃ plants δ¹³C values have been linked to changes in water use efficiency as a response to arid conditions. By calculating ¹³C discrimination (Δ¹³C) from ¹³C isotopic composition (δ¹³C), archaeologists can gain potentially valuable inference into past climate conditions. Values of Δ¹³C reflect the process of discrimination against heavier ¹³C isotopes of carbon by comparing the δ¹³C of samples to that of the atmosphere, and can be calculated when records of atmospheric δ¹³CO₂ are available. The present study examines a 1300 year history of radiocarbon-derived Δ¹³C from the Lower Alentejo of Portugal using charcoal recovered from excavations of a series of medieval habitation sites in the study area. To calculate Δ¹³C, the posterior means generated from Bayesian change-point analysis of δ¹³CO₂ records were used. Archaeological data were then compared to contemporary ecological studies of Δ¹³C of the same taxa against instrumental records of climate. Values of Δ¹³C fell within mean ranges for the taxa through a period of population growth between the 7th and 10th centuries AD. During the height of the Medieval Warm Period in the 11th century AD Δ¹³C values frequently fell to low levels associated with arid conditions. At this time environmental degradation and erosion were documented. Values of Δ¹³C increased for a brief period in the early 12th century AD before the rural Lower Alentejo was largely abandoned for nearly two centuries. Another period of aridity occurred in the 16th and 17th centuries AD. Radiocarbon-derived Δ¹³C is a potentially useful paleoclimate proxy for archaeologists provided that results can be paired with observed Δ¹³C variation in studies that pair these data with instrumental climate records.     

黄瓦窑琉璃构件胎釉原料及烧制工艺研究

黄瓦窑位于我国辽宁省鞍山市海城地区,经专家考证它是专门为清代辽宁地区烧制皇家建筑琉璃构件的窑厂。本文利用X射线荧光渡谱法、X射线衍射法、热膨胀分析等方法研究了黄瓦窑琉璃的胎釉原料及烧制工艺情况。研究表明：黄瓦窑烧制的建筑琉璃为低温铅釉、二次烧成,胎体属于我国陶瓷史上比较少见的MgO—Al2O3-SiO2三元体系,胎体的热膨胀系数比釉层高2～3×10—6／℃。     

The production technology of Iznik pottery—a reassessment*

Previous research has established that Iznik pottery differs from other Islamic stonepaste pottery in that its stonepaste bodies contain lead oxide as well as soda and lime, and that a significant proportion of the tin oxide in its glaze is present in solution rather than as tin oxide particles. In order to better understand these distinguishing features, the chemical compositions and microstructures of Iznik pottery and tile samples, together with those of lumps of glass found in association, were investigated using both scanning electron and optical microscopy. These data have been supplemented by the study of replicate lead–alkali glazes produced in the laboratory with a range of different compositions. The results demonstrate that separate soda–lime and high‐lead glasses were used in the production of Iznik stonepaste bodies, and that the total glass contents of the bodies were significantly higher than those quoted by Abū’l‐Qāsim, who was writing in about ad 1300. The very high purity of the lead–soda Iznik glazes indicated that the alkali flux used was either a purified plant ash or an as yet unidentified mineral source of soda. Replication experiments established that the high solubility of tin oxide in the glaze was due to the high purity of the glaze constituents. Furthermore, it is suggested that tin oxide was added to the glaze in order to give it a very slight opacity and thus obscure any blemishes in the underlying body.     

USING OPTICAL COHERENCE TOMOGRAPHY TO EXAMINE THE SUBSURFACE MORPHOLOGY OF CHINESE GLAZES

Optical coherence tomography (OCT), a new method for ceramics research, is a nondestructive, three‐dimensional tomography system, which provides subsurface morphology visualization of samples based on the refractive index or dielectric constant differences in the target specimen. In this study, seven shards from different Chinese kilns of Song and Yuan dynasties (10–14th centuries) were scanned to visualize the subsurface morphology of their glazes. The images revealed unique phase assemblage modes in different samples. The results suggest OCT may be used to identify ceramics and provide information about their manufacturing technology.     

Coils,slabs, and molds: examining community affiliation between Late Archaic shell ring communities using radiographic imagery of pottery

ABSTRACT

Radiographic imaging is used to determine the techniques used to form vessels from two contemporaneous Late Archaic shell rings in coastal Georgia. These data, in concert with decorative and technofunctional data, suggest that different potting communities occupied each ring. The presence of different communities at each ring corresponds with larger regional patterns in which localized socio-political bodies developed during the Late Archaic. The findings offered in this paper suggest that localized groups did not exist in isolation but rather lived near one another for centuries.