Exploring Bristol’s historic glass industry: archaeological investigation at the Soap Boilers’ and Hoopers’ glasshouses,and the Powell & Ricketts’ Bottle Works,Avon Street,Glass Wharf,Bristol

SUMMARY: In 2007, extensive archaeological excavation was undertaken on an important post-medieval glassworking site at Glass Wharf, Bristol. The excavation exposed remains relating to a series of glassworks dating between the early 18th and early 20th centuries and, significantly, uncovered a sequence of five glass-melting furnaces and covering structures, which together reflect wider changes in glassmaking technology throughout these periods. Detailed scientific analysis of glassworking debris from the excavation has also been undertaken, which provides much-needed detail on the development of recipes and raw materials used in bottle manufacture during the 18th and 19th centuries.     

清朝的玻璃制造与耶稣会士在蚕池口的作坊

天主教耶稣会士纪理安、倪天爵、纪文和汤执中等人在北京任职期间曾经在蚕池口建立了制造玻璃及画珐琅玻璃器皿的作坊。其多数制品是日用工艺品,亦有数学和天文学仪器,而以金星玻璃为代表的佳作则是中国和欧洲宫廷及教廷之间互赠的礼品。本文大量使用西方档案叙述了欧洲的玻璃工艺,特别是吹制、添色、雕刻和抛光技术在中国的传播历程及其由盛转衰的原因。     

Study of medieval glass fragments from Savona (Italy) and their relation with the glass produced in Altare

Altare was in the medieval and post-medieval period an important glassmaking center in the Liguria region in Northern Italy. The first historical evidence of glassmaking in Altare is dated to the twelfth century. In spite of that, due to the continuity of glassmaking up to the present time and the contemporaneous intensive urbanization of the territory, no medieval glass from Altare or its immediate vicinity has been analyzed up to now. In this work, glass from archaeological excavations in the center of Savona, city with close ties with the glassmaking center, was studied. Glass fragments, dated from the tenth to the sixteenth century were selected from the collections of the Archaeological Museum in Savona and non-destructively analyzed with quantitative PIXE-PIGE. The resulting compositions, compared with known glass productions of the same time and evaluated on the basis of historical documents, offer an interesting panorama on the variety of glass circulation in Liguria.     

Eighteenth-century glass and pottery manufacture at Morison’s Haven,Prestongrange, East Lothian

Abstract

This paper presents the results of archaeological investigations of the remains of an 18th-century glassworks at Prestongrange Museum, near Prestonpans, East Lothian. The site is part of an industrial complex previously known as Morison’s Haven, named after its associated tidal harbour. It has a long history of coal extraction that was established as early as the 13th century, and includes industries such as glassmaking, salt, pottery and brick and tile manufacture, and a colliery. The archaeological remains of the glassworks came to light during investigative works designed to locate Gordon’s Pottery, which was known to have manufactured fine tablewares in the 18th century.     

STONES FROM MEDIEVAL GLASSMAKING: A SUITABLE WASTE PRODUCT FOR RECONSTRUCTING AN EARLY STAGE OF THE MELTING PROCESS IN THE MT LECCO GLASS FACTORY*

The Mt Lecco glass factory was one of the most important production centres in Liguria (Italy) during the 14th and 15th centuries. Archaeological evidence indicates that the whole production cycle took place here. During the glassworking process, production defects such as ‘stones’ were identified and discarded. Stones are partially melted, glass‐coated relics of raw materials or fragments of crucible. The study of the microtexture of stones together with microprobe analyses of phases provides a key for understanding the glassmaking procedure carried out in the Mt Lecco glass factory. The melting rate can be inferred from the compositional variability of glass, which suggests fractional melting of the batch. Glass composition indicates that the Mt Lecco production was a mixed‐alkali one, probably made of quartz‐bearing material as vitrifying agents, plant ashes as fluxing agents and dolomitic limestones as stabilizing agents.     

Excavation of an early 17th-century glassmaking site at Glasshouse,Shinrone, Co. Offaly,Ireland

An archaeological research excavation was conducted in the area immediately surrounding an upstanding glassmaking furnace near Shinrone, Co. Offaly, Ireland. It dates to the early to mid 17th century and was built and operated by French Huguenots, probably de Hennezells (de Hennezel/Henzeys/Hensie) who had settled in this region as part of the Crown plantation of King’s County (now Co. Offaly). This furnace, which employed wood rather than coal as a fuel, is a very rare survival, with no other upstanding examples known in Ireland, Britain or the Lorraine region of France where the form probably originated.     

Western Mediterranean sand deposits as a raw material for Roman glass production

During the Late Roman and Byzantine period, natron glass was made from its raw materials in a limited number of primary production centres in Egypt and Syro-Palestine. For the earlier Hellenistic and Roman period, no primary furnaces have been found and the location of primary production during this era remains unclear. Ancient authors such as Strabo and Pliny the Elder suggest that glassmaking sands were found near the River Belus (Israel), in Egypt, near the mouth of the Volturno River (Italy) and also in Spain and France. However, primary production in the western part of the Mediterranean is not supported by any direct archaeological evidence and possible sand raw materials from these regions have never been evaluated for their suitability to produce glass.     

THE ANALYSIS OF SECOND MILLENNIUM GLASS FROM EGYPT AND MESOPOTAMIA,PART 1: NEW WDS ANALYSES*

A recent analytical study by SEM–WDS was carried out on 226 glasses from the Late Bronze Age, analysing each of the glasses for a total of at least 22 elements, the largest such analytical study conducted on these glasses. The aim of the analysis was first to identify which elements were brought in with each of the raw materials and, second, to accurately characterize those raw materials. Since different glassmaking sites in Egypt and the Near East would probably use at least some local raw materials and these raw materials will vary slightly from site to site, this has potential for provenancing the glass. Analysis showed new patterns in the compositions of glass from the various sites and led to new conclusions about the supply of raw materials and personnel for the glass workshops. This forms the basis for further work by LA–ICPMS to be presented in part 2 of this paper.     

Potash - a key raw material of glass batch for Bohemian glasses from 14th-17th centuries?

The aim of this work is to verify or refute hypothesis of existence of basic/universal glass batch: quartz sand: potash: limestone, at a ratio of 2: 1: 1 used in Bohemian glass production since the middle ages onwards and to simulate the preparation of a potassium glass type with the composition used in medieval Bohemia. The chemical composition of Bohemian glass, which incorporated in the proposed glass batch for glassmaking on a laboratory scale, was evaluated by (a) findings directly related to glassmaking (samples from glasswork in Moldava dating back to the 15th century) and (b) information from publications.Experimentally produced glasses for the present paper were prepared from raw materials such as ash, leached ash, potash, limestone and quartz sand. The plant raw materials (spruce, beech and bracken ashes, raw and refined potash) were treated and prepared by methods similar to the production procedures used in the pre-industrial era.The main contrast was found in the CaO/K₂O weight ratio, which was determined in glasses that were characteristic of given periods. While this ratio was often below 1 in glasses of the 15th century, it reached values above 1 in glasses at the turn of the 16th-17th centuries. This result may indicate that the composition of the glass batch had changed.The results of the present study reject the current scholarly work dealing with glass batch composition during the 14th-17th centuries and confirm that glass produced in some Bohemian medieval glassworks could have been melted from a batch that included plant ash, making the use of limestone unnecessary. The traditional suggestion of the exact ratios of raw materials, often cited in historical literature, seems to be impossible. The glassmakers had to react to the variable composition of the raw materials, especially plant ash.     

New insights into Byzantine glass technology from loose mosaic tesserae from Hierapolis (Turkey): PIXE/PIGE and EPMA analyses

This study focuses on the Byzantine glass tesserae from Hierapolis (Phrygia, central Turkey). Fifty-seven samples of loose tesserae from two sites in the town (the theatre and the church of St. Philip) are analysed by particule-induced X-ray emission and particule-induced gamma ray emission and electron probe X-ray microanalysis to obtain the chemical composition and identify the colourants and opacifiers. The aims are to add new information to the scant knowledge of the Byzantine glassmaking technology, to constrain the chronology of the mosaics and to trace the supply routes of the tesserae. In the destruction layers of the theatre, tesserae produced following the Roman glassmaking technology (natron glass opacified by calcium and lead antimonate) were found. They were made using a Levantine 1 raw glass, generally attributed to the early Byzantine period (fifth to sixth c.). In the church, the samples attest a technological change from Roman tradition, and a complex pattern according to building history (two phases are attested, probably in the sixth and eighth to ninth c.), and a multiplicity of supply. Three glass types and some recipes not attested before in this chronological range for the production of tesserae are documented, such as the use of a local low-chlorine natron glass for the production of black and red tesserae, the blue colouring by a source of cobalt with zinc in a natron glass tessera and the opacification with tin oxide (both in a lead-free and in a high-lead natron glass), as well as with quartz.     

Analysis of polychrome Iron Age glass vessels from Mediterranean I,II and III groups by LA-ICP-MS

In this work the analytical results obtained by ICP-MS with laser ablation solid sampling and SEM-EDS for some polychrome glass vessels from the Iron Age are presented and discussed. The samples, coming from Etruscan sites near Adria (Northern Italy), belong to the so-called Mediterranean Groups I, II and III and are dated from the 5th, 3rd and 2nd century B.C., respectively. To date, analytical data for only two sets of vessels of the Iron Age have been discussed in the literature. In spite of the low number of available samples, this is the first time that vessels of all three periods are analytically compared. Elemental concentration data show that the samples can be classified as low-magnesia-low potash (LMLK) soda-lime-silica glasses, with low phosphorus and titanium contents, in agreement with data for similar samples of the same age. Bivariate and multivariate analyses of the contents of many elements characterizing the siliceous sands showed three distinct sets corresponding to the three periods. Since the sets indicate different provenances of the sands it seems rational to assume that different glassmaking locations were involved. Chromophores and opacifiers of the blue bodies and the yellow, white and turquoise decorations of the vessels were analytically identified, while the nature of the corresponding ores was hypothesized.     

Radical changes in Islamic glass technology: evidence for conservatism and experimentation with new glass recipes from early and middle Islamic Raqqa,Syria*

The chemical analysis of excavated glass fragments from dated archaeological contexts in Raqqa, Syria, has provided a detailed picture of the chemical compositions of artefacts deriving from eighth to ninth and 11th century glassmaking and glassworking activities. Evidence for primary glass production has been found at three excavated sites, of eighth to ninth, 11th and 12th century dates; the first two are discussed here. The 2 km long industrial complex at al‐Raqqa was associated with an urban landscape consisting of two Islamic cities (al‐Raqqa and al‐Rafika) and a series of palace complexes. The glass fused and worked there was presumably for local as well as for regional consumption. Al‐Raqqa currently appears to have produced the earliest well‐dated production on record in the Middle East of an Islamic high‐magnesia glass based on an alkaline plant ash flux and quartz. An eighth to ninth century late ‘Roman’/Byzantine soda–lime recipe of natron and sand begins to be replaced in the eighth to ninth century by a plant ash – quartz Islamic soda–lime composition. By the 11th century, this process was nearly complete. The early Islamic natron glass compositional group from al‐Raqqa shows very little spread in values, indicating a repeatedly well‐controlled process with the use of chemically homogeneous raw materials. A compositionally more diffuse range of eighth to ninth century plant ash glass compositions have been identified. One is not only distinct from established groups of plant ash and natron glasses, but is believed to be the result of experimentation with new raw material combinations. Compositional analysis of primary production waste including furnace glass (raw glass adhering to furnace brick) shows that contemporary glasses of three distinct plant ash types based on various combinations of plant ash, quartz and sand were being made in al‐Raqqa during the late eighth to ninth centuries. This is a uniquely wide compositional range from an ancient glass production site, offering new insights into the complexity of Islamic glass technology at a time of change and innovation.     

Evidence of early medieval soda ash glass in the archaeological site of San Genesio (Tuscany)

The early medieval period marks an important turning point in the history of glassmaking, since it comprises the transition period between the mineral-based silica-soda-lime glass of the Roman tradition and the plant ash-based glass. With the aim of expanding the knowledge on the glass recipes and technologies of this period, 37 glass samples were analyzed, originating from the archaeological excavations of San Genesio (Tuscany) and dated from the fourth to the eleventh century. The major and minor element concentrations were measured with SEM-EDX, while the trace elements were quantified with LA-ICP-MS. The results were compared with published compositions of glass samples of similar age in order to highlight differences and similarities. The results offer a very interesting view on the glass circulation in the religious/residential/manufacturing center of San Genesio in the early medieval period. Most of the glass has a typical late-Roman composition, but some glass fragments are identified as soda ash glass. These are among the earliest medieval ash-fluxed glasses ever found in the Italian peninsula.     

WHO WERE THE GLASSMAKERS? STATUS,THEORY AND METHOD IN MID‐SECOND MILLENNIUM GLASS PRODUCTION

Summary.   Glass was first produced in a regular and controlled manner in the Near East in the sixteenth century BC. This paper examines a wide variety of textual, archaeological and analytical sources to try and determine more about the makers of this first glass. It attempts to show how modern ideas about medieval glassmaking have been anachronistically applied to the second millennium BC, and readdresses this by turning instead to second millennium sources of evidence. Using these sources, it investigates the position of glass within Late Bronze Age society and the status of glassmakers themselves. It goes on to examine the evidence for ritual and experimental behaviour in LBA crafts and industries and applies this to ideas of technological innovation and change in the period. It looks at the alchemical nature of glass production and proposes new ways of attempting to understand the glassmakers themselves.     

DEEPLY COLOURED AND BLACK GLASS IN THE NORTHERN PROVINCES OF THE ROMAN EMPIRE: DIFFERENCES AND SIMILARITIES IN CHEMICAL COMPOSITION BEFORE AND AFTER ad 150*

In this work we attempt to elucidate the chronological and geographical origin of deeply coloured and black glass dating between 100 bc and ad 300 on the basis of their major and trace element compositions. Samples from the western and eastern parts of the Roman Empire were analysed. Analytical data were obtained by means of a scanning electron microscope – energy‐dispersive system (SEM–EDS, 63 samples analysed) and laser ablation – inductively coupled plasma – mass spectrometry (LA–ICP–MS, 41 samples analysed). Among the glass fragments analysed, dark brown, dark purple and dark green hues could be distinguished. Only among the dark green fragments could a clear compositional distinction be observed between fragments dated to the periods before and after ad 150. In the early samples (first century bc to first century ad ), iron, responsible for the green hue, was introduced by using impure sand containing relatively high amounts of Ti. In contrast, a Ti‐poor source of iron was employed, containing Sb, Co and Pb in trace quantities, in order to obtain the dark green colour in the later glass samples. The analytical results obtained by combining SEM–EDS and LA–ICP–MS are therefore consistent with a differentiation of glassmaking recipes, detectable in glass composition, occurring in the period around ad 150.     

Glassmaking using natron from el-Barnugi (Egypt); Pliny and the Roman glass industry

Pliny the Elder describes the discovery of a process for making natron glass, which was widely used for much of the first millennium bc and ad. His account of glassmaking with natron has since been corroborated by analyses of archaeological glass and the discovery of large-scale glass production sites where natron glass was made and then exported. Analyses of Egyptian natron have shown it to be a complex mixture of different sodium compounds, and previous experiments to make glass with Egyptian natron have been unsuccessful. Here, natron from el-Barnugi in the Egyptian Nile delta, a site which also probably supplied Roman glassmakers, is used to produce glass. The experiments show that high-quality glass, free of unreacted batch or bubbles, could have been produced from natron in its unprocessed form in a single stage, that larger quantities of natron would be required than has previously been anticipated, that the presence of different sodium-containing compounds in the deposit aided melting, and that negligible waste is produced. The implications for the identification of glass production sites, for the organisation of trade and for the supply of natron within and outside Egypt are discussed in the light of Pliny’s accounts.     

Urban geo-archaeology in medieval alzira (Prov. Valencia,Spain)

Alzira is situated in a cut-off meander loop of the Rio Júcar. Geo-archaeological study shows that the Islamic city wall was built during the second quarter of the 11th century AD, at a time when the river had a low-amplitude and low-energy flood regime. After mid-century, overbank silts began to invade the city as peak flood discharge increased, with a spate of destructive floods reflected by high-energy deposits during the late 11th century. Urban expansion within the city wall is dated to the later 11th or early 12th century, interrupted by local abandonment and moderate-energy flood silts. Major construction during the mid-12th century was followed by protracted abandonment (after a siege in AD 1171?) and further, moderate-energy flood silts that redistributed occupation and collapse debris. Reoccupation, during the late 14th century, was terminated by catastrophic floods in 1517 and 1571, after which much of the western end of Alzira was not rebuilt. Following further flood catastrophes during the 17th century, parts of the central walled city remained abandoned until the 19th century. with new occupation atop flood sands of yet another disaster in 1864. The change in flood regime after 1150 was a result of deforestation of the watershed, but progradation of a downstream tributary fan after 1517 created an unstable, aggrading floodplain increasingly prone to severe flooding. Climatic anomalies were responsible for periods of recurrent severe floods, archaeologically verified during the 11th and 12th centuries, and historically documented, beginning in 1318. The geo-archaeological methodology illuminates the constructional and settlement history of Alzira, allows distinction of fluvial and cultural components, and provides the necessary microstratigraphic detail and dating control to document the true complexity of alluvial processes during the last 1000 years.     

Transitions in Islamic plant-ash glass vessels: on-site chemical analyses conducted at the Raya/al-Tur area on the Sinai Peninsula in Egypt

This study focuses on the chemical composition of Islamic plant-ash glass (dated from the 9th to 11th centuries) excavated from the Raya/al-Tur area on the South Sinai in Egypt. Plant-ash glass objects from the Raya site were classified into three compositional types based on on-site chemical analyses with a portable X-ray fluorescence spectrometer. Based on typological characteristics and chemical composition comparisons with contemporary glass objects from other Islamic sites, one hypothesis holds that plant-ash glass objects produced in the Syria–Palestine or Mesopotamian regions could have been imported to Raya during the 9th to 10th centuries. In particular, some colorless glass vessels with a high magnesium/calcium ratio were noted to exhibit post-Sassanian cut decorations. Conversely, most of the bluish-green plant-ash glass objects from the Monastery of Wadi al-Tur near the Raya site exhibited relatively high levels of aluminum, titanium, iron, and lead. These pieces were likely produced during the Fatimid period (late 10th to 12th centuries), and based on their elemental composition, possibly originated in Egypt. The present work provides a greater understanding of chronological changes in post-9th century Islamic plant-ash glasses and the development of social and commercial networks within the Middle Eastern area.     

Crusaders’ castles—the fourth generation: reflections on Frankish castle-building policy during the 13th century

This paper examines Frankish castle-building policy during the 13th century through two case studies, Château Pèlerin and Montfort. During this period, castles were built mainly by the military orders, in the same locations as, or very close to, existing fortifications. Furthermore, these activities often coincided with the presence of a crusade in the region. In the two case studies the initiators of the projects had reasons other than military to execute them. The main conclusion of this paper is that during the 13th century castles were not built in the Latin kingdom of Jerusalem for strategic reasons or according to a well defined programme, but in order to meet a series of religious, moral, social as well as economic and political considerations. This conclusion may imply that this was the case also during the 12th century.     

Insect Assemblages and Local Environment in the Mediaeval Town of Uppsala, Sweden

Insect remains from a mediaeval settlement in the town of Uppsala, S. Sweden, were analysed. Eighty-one insect taxa were identified from samples dating from the 12th to the 15th century. The insect assemblages are totally dominated by beetles. Only a few remains of butterflies, true flies and a bumble bee were found. The insects imply that the settlement was situated in open landscape. The settlement most likely consisted mainly of farm buildings throughout the studied period. Crops such as wheat, barley and cabbage were probably cultivated, particularly during the early settlement phases. Later, at the beginning of the 15th century, stock rearing seems to have dominated. The results suggest that the climate, during Mediaeval time in southern Sweden, was similar to the present or characterized by slightly higher summer temperatures. A number of currently very rare species were also recorded.