Lead Glaze Research Articles

Chromogenic mechanisms of overglaze yellow pigment produced in Jingdezhen imperial kilns during the Ming dynasty

This study employed energy-dispersive X-ray fluorescence spectrometry, Raman spectroscopy, X-ray photoelectron spectroscopy, and ultraviolet–visible-near infrared spectrophotometry to analyse eleven overglaze pigment porcelain specimens. The results show that the colouring element of the overglaze yellow pigment of Jingdezhen imperial kilns in the Ming dynasty is Fe2O3, and most of Fe2O3 can be dissolved in the lead glaze in an ionic state to make the lead glaze yellow. The chromogenic of the overglazed yellow pigment primarily depends on the concentration and coordination field of the colouring ions. The connection between the internal structure and the appearance of the overglaze yellow pigment is discussed.

Study on the Chemical Composition and Lead Isotope Ratios of Lead Glaze Used on Blue Tiles from Gyeoungbokgung Palace

Study on the Chemical Composition and Lead Isotope Ratios of Lead Glaze Used on Blue Tiles from Gyeoungbokgung Palace

A Comparative Study of the Use of Japanese Majolica Tiles in Modern Japan and Japanese Colonial Taiwan

This paper discussed the connection between “Japanese majolica tiles” in modern Japan and Japanese colonial Taiwan, and the differences in the way tiles are used during these periods from both Japanese and Taiwanese perspectives. Japanese majolica tiles were manufactured in Japan primarily during the Taisho period (1912-1926) and early Showa period (1926-1945), with relief surfaces covered with multicolored lead glazes. The tiles produced in Japan at that time were mainly imitations and developments of a Victorian tile product called majolica, which was imported from England and exported to countries around the world. The results of the survey indicate differences in the use of tiles, with their usage in different architectural styles and cultures becoming apparent. In Japan, the connection between tiles and modern concepts can be noted. In addition, post-modern tile production and architectural preservation suggest that differences in the amount of extant Japanese majolica tiles in Japan and Taiwan have arisen.

An Archaeometric Study of Lead-Glazed Medieval Ceramics (13th–14th Century) from Santarém, Portugal

Ceramic sherds from approximately 20 samples of lead-glazed tableware, recovered from diverse archaeological sites, including three repurposed storage pits transformed into dumpsters within the medieval city of Santarém (13th–14th century), underwent a meticulous examination. This investigation utilised techniques such as micro-Raman, ground-state diffuse reflectance absorption, and X-ray fluorescence spectroscopies, in addition to X-ray diffraction and stereomicroscopy. A parallel study was conducted on contemporaneous European ceramics (glazed sherds) sourced from archaeological sites dating back to the 13th–15th centuries in Saintonge (France), Ardenne, Zomergem, and Bruges (Belgium), as well as Surrey–Hampshire, Kingston, and Cheam (England). The first premise for comparing the Santarem samples with European production locations was their frequent commercial relations with Portugal and the frequency of these productions being found in Portugal. The colour of the ceramic bodies is predominantly white or whitish, with a few exhibiting a vivid red hue. Analyses of the fabric, mineralogical, and elemental composition of the sherds suggest that the majority of Santarém’s glazed ceramics were locally or regionally produced, potentially derived from a Pliocene kaolin-rich sand formation. However, this conclusion is not supported by the absence of discovered lead glaze kilns or workshops in Santarém for the late Middle Ages.

Lead Transfer Risk from Handling Ceramics with Deteriorated Lead Glazes

ABSTRACT The risks of lead transferring to gloves while handling lead-glazed ceramics was evaluated with simple empirical tests using Plumbtesmo test strips. Five lead-glazed ceramics from the Harvard Art Museums, three with deteriorated glazes and two with glazes in good condition, were evaluated along with three controls. The objects and controls were handled using three interaction types (touch and hold, tapping, and rubbing); the presence of lead on gloves was then evaluated using Plumbtesmo test strips. The experiment demonstrated that ceramics with deteriorated lead glazes have the potential to transfer lead to gloves during handling. Collections care staff working with lead glazed ceramics are advised to take precautions during handling and uphold best practices for hygiene to minimize lead exposure.

Petrographic and lead isotope analyses to assess regional variability in Rio Grande Glaze wares from New Mexico

The broad spatial distribution and long period of production of Rio Grande Glaze Ware vessels hides considerable material diversity within the typological grouping as a ware. This has long made archaeometric techniques attractive options for understanding variability within the Rio Grande Glaze Ware category. We present the results of new petrographic analysis of Rio Grande Glaze Ware pastes and new isotopic analysis of Rio Grande Glaze Ware glaze paint. The results of these new analyses complement extensive earlier work characterizing both Rio Grande Glaze Ware pastes and paint. Especially relevant is the identification of glaze paints made primarily with lead ores from the Hansonburg district or made by mixing Hansonburg ore with the more commonly used Cerrillos district ores. The predominant use of Cerrillos ore in the production of lead glaze paint identified in prior work is nuanced through the additional data presented here, which suggests a division in networks of lead ore and/or glaze paint procurement between a larger, northern network making use of Cerrillos ores, and a smaller, southern network relying on Hansonburg ores for glaze paint production.

Research on the degradation mechanism of the lead-glazed cups from the ‘Yangtze River estuary No. 2’ shipwreck

The ‘Yangtze River Estuary No. 2’ shipwreck of the Qing Dynasty (1636–1912 CE) is one of the most well-preserved ancient wooden shipwrecks discovered underwater in China to date. Unfortunately, most green lead-glazed cups salvaged out of the shipwreck have severely degraded and generally blackened in the underwater environment. In this study, the degradation mechanism of the lead glaze in the underwater environment were investigated in depth. It was found that the degradation of lead glaze involved several complex chemical and physical processes. The special environmental conditions caused by the corrosion of iron components in the shipwrecks may be an important reason for the loss of Si elements in corrosion layers. The appearance changes of the green glaze are related to the leaching of Cu2+ ions and the gradual transformation to a lead-rich corrosion layer. The iridescent phenomenon may be related to the thin-film interference of the laminated corrosion layers.

Preparation and mechanical properties of cubic boron nitride reinforced lead glaze layers of a gradient structure

Lead glaze possess excellent radiation ray shielding ability, and it is an efficient way to stop radiation spillover by using lead glazed indoor titles in a building. The merit of low firing temperature of lead glaze is, however, associated with its poor wear resistance. Here super-hard cubic boron nitride (cBN) particles, of a neutron shielding property, are introduced into the soft glass matrix to improve its mechanical properties. Results show that, at meticulously tailored conditions, the lead glaze surface is successfully enriched with cBN particles due to the lower density of cBN relative to the glaze. With 5 wt% cBN particles embedded in the glass matrix, the hardness increases by 51.2% and more importantly, the glaze yields significantly improved wear resistance. The finite element analysis reveals that the cBN particles enhance the toughness of the glaze, a key factor to wear resistance, by reducing the crack tip stress concentration.

Microstructure composition and characterisation of green glazed ceramics in Ujan (NW IRAN); A multianalytical investigation

This article aims to study the composition of clay-based bodies and the morphology of slip and glaze on 21 samples excavated at Ujan archaeological sites in 2018. This ancient city is located in the northwest of Iran, 55 km southeast of Tabriz. The city functioned well during the 11th to 18th centuries and was the ruler’s summer capital during the Ilkhanid period. The study and analysis of types of pottery found in this area offers direct connections about the extension of lead glazes techniques on sgraffito pottery.. The samples were studied by microscopic examinations (OM, petrography, and SEM), and SEM-EDS was used to study chemical composition to obtain information about the manufacturing technology of green glazed ceramics. The results indicate that the body material were localized and consistent with the minerals and structures of the around Ujan. The investigation of the chemical structure of the glaze also shows that they are lead-rich and mainly stained with copper oxide. The chemical composition of the interface layer between the glaze and the slip in some samples shows large amounts of Pb, Si, Al, and K oxides that indicate the formation of lead feldspars and determine the glaze firing temperature.

Manganese crystalline phases developed in high lead glazes during firing

A High Temperature Synchrotron Radiation X-Ray Powder Diffraction experiment was performed to determine the manganese compounds formed during the heating and cooling of 70 wt% PbO – 30 wt% SiO2 mixture or the equivalent glass plus 10 wt% of MnO. The effect of adding calcite, dolomite and kaolinite were also studied. All mixtures were fired between 690 °C and 1020 °C in oxidizing conditions and analysed by Scanning Electron Microscopy.A sequence of manganese phases are formed during firing: bixbyite (Mn2O3), barysilite ((Pb,Mn)Si2O7), kentrolite (Pb2Mn2Si2O9) and braunite (Mn7SiO12). Kentrolite and braunite crystallise with different crystal habits during the heating and the cooling. If dolomite is present diopside ((Ca,Mg,Mn)2Si2O6) is formed. If calcite is present, ganomalite (Pb3(CaMn)2Si3O11), margarosanite (Pb(Ca,Mn)2Si3O9) and wollastonite ((Ca,Mn)SiO3) are also formed. Wollastonite can incorporate enough manganese to transform into bustamite ((Mn,Ca)3Si3O9) at high temperatures. This leaves less manganese available for the crystallisation of kentrolite and braunite.

Glaze characterization of the glazed pottery from the medieval workshop of Vega (Burgos, Spain)

AbstractSixteen glazes on medieval (14th–16th century AD) pottery fragments from Vega pottery workshop (Burgos, Spain) were characterized to investigate the production technology. To this end, Raman spectroscopy and scanning electron microscopy coupled with energy dispersive X‐ray spectroscopy (SEM‐EDX) were used. The studied glaze samples correspond to fragments of high‐quality glazed ware used by the wealthiest society in the city of Burgos. The most representative types of glazes, corresponding to honey‐marble, honey‐yellow, bright light green, and dark green types, were analysed. Raman spectroscopy shows lead was used as a fluxing agent in glaze production. SEM‐EDX analysis confirms the use of lead oxide and evidences that most of the samples underwent at least two firing processes. No Raman signals of crystalline phases were detected on either glaze surfaces or glaze thin‐sections. The exception is the single firing of dark green glazes, which show pseudobrookite and rutile at the clay body/glaze interface measured in thin section. No colouring crystalline phases were identified by Raman spectroscopy either. However, SEM‐EDX shows iron was the most‐used colouring agent whereas copper was used for bright light green glazes. The polymerization index (Ip) values were used to estimate the firing temperatures. The polymerization index values are typically low for lead glazes and indicate firing temperatures below 700°C.

The coordination structure and optical property of iron ions in the traditional lead glazes

Iron could produce bright colors from yellow to brown in Tang Sancai lead glaze, a kind of important ceramic product from ancient China. The glaze color appearance is the most typical feature of Sancai wares, and it is a topic of great interest to scholars and potters. In this paper, we investigated the relationship between atomic-scale microstructure near iron ions and optical properties. The compositional analysis and X-ray absorption fine spectroscopy indicated that the iron ions in Sancai lead glazes were mainly in tetrahedral coordination structure, isolated [Fe3+O4]. The d-d absorption band of Fe3+ is the fundamental factor affecting the glaze color appearance. The tetrahedral coordination structure is the reason for the high intensity of this band. And, the adjustment of glaze composition (content of Pb and Fe) could change its width.

Thermophysical modeling of raw glaze liquidus temperature and viscosity

AbstractRaw glazes, which do not contain pre‐melted glass frits, are widely used due to their low cost. The natural variability of the mineral compositions used in raw glazes affects their viscosity during firing. Molten glaze viscosity plays an important role in determining the final surface quality; therefore, it is important to determine how raw glaze composition and firing conditions affect viscosity. Thermophysical modeling provides a way to evaluate the liquidus temperature and viscosity of molten glazes as a function of composition and oxygen activity. Equilibrium phase volume fraction and composition of 242 raw glaze recipes were evaluated under oxidizing and reducing conditions. Undissolved or precipitation of solid phases explains the secondary flux transition from anti‐fluxing to fluxing near the liquidus temperature. The liquidus temperature and viscosity of iron glazes decrease as a function of increasing iron content under a reducing atmosphere. The empirical probability distribution of molten glaze viscosity follows a lognormal distribution, with lead glazes having significantly lower viscosity compared with glazes without lead. The peak firing temperature viscosity of lead‐free glazes is near the working point of glass. Multiple linear regression analysis shows that the peak firing temperature viscosity and liquidus temperature significantly predict the viscosity factor.

Bodies and Glazes of Architectural Ceramics from the Ilkhanid Period at Takht-e Soleyman (North-Western Iran)

Bodies and glazes of tiles from the Ilkhanid period found at the UNESCO World Heritage site of Takht-e Soleyman were studied to identify materials and certain technical characteristics of the architectural ceramics as part of a larger project to establish different productions. In addition, ceramic vessels and technical ceramics excavated at the site were analysed for comparison. µXRF, SEM/EDX, and Raman spectroscopy were used for the material investigations. Qualitative non-invasive µXRF results allowed for categorisation of the glazes and ceramic bodies based on their overall composition. Quantitative analysis by SEM/EDX on a subset of the samples delivered detailed results on the bodies and glazes. Tiles, made from clay or stonepaste, were almost exclusively decorated with a mixed alkaline lead glaze. The PbO content of this type of glaze ranged from 8 wt% to 25 wt%. The clay bodies of some tiles corresponded to the material of the locally used kiln furniture. Moreover, glaze residues preserved on the kiln furniture proved to be from a mixed lead alkaline glaze with a PbO content of 15 wt% to 25 wt%, a composition that is comparable to the tiles’ glazes. For more insights into the local or regional production of the tiles, supplementary in-depth studies including petrographic analysis would be needed to confirm and further specify the results.

Three-colored Sancai glazed ceramics excavated from Bohai sites in Primorye (Russia)

This paper presents the analytical results of polychrome and monochrome lead-glazed ceramic classified as Sancai that was excavated from the Bohai sites of Kraskino and Gorbatka walled towns, and the Chernyatino-2 settlement (Bohai layer) (Primorye, Russia). Thirty ceramic fragments were analyzed using non-destructive X-ray fluorescence analysis (pXRF), optical microscopy, and scanning electron microscopy (SEM) with energy-dispersive x-ray spectroscopy (EDS). This work presents new data on the elemental composition of lead glazes and discusses some aspects of their technology, including assumptions about the medieval potters' skill level and technological awareness. Data pertaining to the sample's elemental composition indicates their origin from various workshops practicing different approaches to pottery production. These ceramics have no slip layer with the glaze coating having been applied directly onto the surface of the ceramic vessels. The intensity of the lead component in the glaze composition varies significantly, in the range of concentration between 36 and 79 wt%. Surface features of filling and shine, as well as the nature of glaze defects demonstrates a low probability of the peak firing approach that was applied in the technological process. The results presented in this paper contribute to expanding our understanding of the Bohai (CE 698–926) and Tang (CE 618–907) periods for Sancai ceramics.

A Summary of the Comparative Study of Lead-Glazed Pottery in Han Dynasty and Ancient Egypt

During the reign of Emperor Wudi of the Western Han Dynasty, lead-glazed pottery was successfully fired in China. Compared with previous pottery, glazed pottery was more suitable for use because of its advantages of low water absorption and high finish. However, in the world, the use of glazed pottery technology first appeared not in China, but in ancient Egypt, so there is also a saying that the lead glaze technology on the Han Dynasty pottery was spread from the western regions, rather than the invention of Chinese craftsmen. In this article, the author will try to make a comparative study and analysis of lead-glazed pottery in Han Dynasty and ancient Egypt from the aspects of process principle, product use and aesthetic fashion.

Characterisation of archaeological ceramics from Saadian Tombs (16th century) of Marrakech Morocco

The analysis of archaeological materials can provide information to protect the cultural heritage of civilizations, allowing inferences about their technology and interaction with their surrounding physical and social environments. In this context, the present paper proposes an analytical methodology to characterize samples of ancient ceramic objects (dating to 16th century) from the Saadian Tombs of Marrakech, one of the main Saadian buildings in Morocco. A multi-analytical approach based on optical and scanning electron microscopy, cathodoluminescence, X-ray fluorescence and X-ray diffraction was used to determine the textural, mineralogical and chemical characteristics of these materials. The obtained results allow probing into the past and attempt to re-create prehistory by obtaining information about the provenance and manufacturing proprieties of these archaeological objects. The Saadian artisans have used calcareous clay as raw material to manufacture their decorative ceramics called zellige. These materials are composed of lead glaze applied directly on a silicate shard without ceramic engobe or intermediate layer. The coloring agents are conventional, iron (Fe3+) for the yellow glaze, manganese (Mn3+) for the black glaze, copper (Cu2+) and phosphorus (P) for the green and blue glazes. The estimated firing temperature of these materials ranges between 800 and 900 °C.

Investigation of provenances of Early Islamic lead glazes from northern Central Asia using elemental and lead isotope analyses

Investigation of provenances of Early Islamic lead glazes from northern Central Asia using elemental and lead isotope analyses

THE IMPACT OF LEAD-CONTAINING SLAG WASTES ON THE LIFE SAFETY

The article presents the analysis and results of the study of technogenic slag waste of lead-zinc production. Lead-containing slag waste contains a large number of toxic compounds of heavy metals, such as lead, zinc, osmium, cadmium, which are dangerous sources of environmental pollution. Due to the open storage of slags, there is an excess of the maximum permissible concentrations (MPC) of lead: near the plant, the concentration of lead is more than 3000 mg/kg in the soil, with an MPC of 3.2 mg/kg. Lead and zinc compounds are dangerous for humans due to their significant toxicity and the ability to accumulate in the body. The article presents the analysis and results of studies of lead-containing slags on toxic compounds and their impact on human health. The results of the conducted studies have shown that poisoning with lead-containing toxic slags leads to such consequences as damage to the brain, nervous system, cardiovascular system, digestive system, kidneys, and blood in children and adults. According to the research results, lead gets into products from dishes (covered with lead glaze) and showers. In the blood–basophilic granularity of red blood cells, reticulocytosis. The increase in the lead content in the urine is more than 0.04 mg /l.

From Glass to Glaze in al-Andalus: Local Invention and Technological Transfer

It has long been assumed that lead glazing technology preceded glassmaking in the Western world and that the technological transfer was from glazes to glass. Here, we present new evidence for the reverse, the indigenous innovation of glassmaking and its transfer to glazes in early Islamic al-Andalus (Spain). Compositional analyses show that Islamic lead glazes from Córdoba are intimately related to a distinct type of high-lead glass, suggesting a connection between the two technologies. The archaeological remains from a pottery workshop indicate that the glazing process initially involved the production of a lead glass and is not linked to earlier Roman or other contemporary glazing technologies. The data also demonstrate that the potters not only used the same materials and techniques but borrowed stylistic and decorative models from glassmaking.