Laser ablation inductively coupled plasma time-of-flight mass spectrometry (LA-ICP-TOFMS) was use... more Laser ablation inductively coupled plasma time-of-flight mass spectrometry (LA-ICP-TOFMS) was used to study the trace element chemistry of coral red and black gloss slip decoration on Greek Attic pottery (6th century BC). The distribution of trace elements in the body fabric and glaze slips were found to be correlated suggesting the raw materials came from a single source. Furthermore, the so-called high calcium and magnesium (HCM) coral red was found to be a less refined material than black gloss, with trace element characteristics suggestive of a carbonate phase in the raw material. This carbonate component may have imparted refractory properties to the HCM coral red slip material during the three-stage oxidative-reductive-oxidative firing used to produce Attic pottery, allowing it to remain porous and re-oxidize during the final firing step, thus creating its final red color. The so-called low calcium and magnesium (LCM) coral red, on the other hand, was found to be more refined ...
Portrait of a Child: Historical and Scientific Studies of a Roman Egyptian Mummy, 2019
Introduction to Portrait of a Child: Historical and Scientific Studies of a Roman Egyptian Mummy,... more Introduction to Portrait of a Child: Historical and Scientific Studies of a Roman Egyptian Mummy, Essi Rönkkö, Taco Terpstra, and Marc Walton eds. (Evanston: Block Museum 2019)
As one of the most desired and expensive artists' materials throughout history, there has long be... more As one of the most desired and expensive artists' materials throughout history, there has long been interest in studying natural lapis lazuli. The traditional method of extracting the blue component, lazurite, from lapis lazuli, as outlined in Cennini's Il Libro dell'Arte, involves a lengthy purification process: (1) finely grind the rock; (2) mix with pine rosin, gum mastic, and beeswax; (3) massage in water to collect the lazurite. Repeating the process produces several grades of the pigment, typically referred to as ultramarine blue. Here, we investigate the sulfur environment within the aluminosilicate framework of lazurite during its extraction from lapis lazuli. The sulfur XANES fingerprint from samples taken at the different stages in Cennini's extraction method were examined. All spectra contain a strong absorption peak at 2483 eV, attributable to sulfate present in the lazurite structure. However, intensity variations appear in the broad envelope of peaks between 2470 and 2475 eV and the pre-peak at 2469.1 eV, indicating a variation in the content of trisulfur (S 3 − ˙) radicals. By studying the effect of each step of Cennini's process, this study elucidates the changes occurring during the extraction and the variability within different grades of the precious coloring material. The increasing application of XANES to the study of artist's materials and works of art motivated extending the research to assess the possibility of X-ray induced damage. Direct comparison of micro-focused and unfo-cused beam experiments suggests an increase of the S 3 − ˙ radicals with prolonged exposure. Analysis indicates that induced damage follows first-order kinetics, providing a first assessment on the acceptable amount of radiation exposure to define the optimal acquisition parameters to allow safe analyses of lapis lazuli and ultramarine pigments.
It had long been believed that the plastic substrates of László Moholy-Nagy's paintings T1 (1926)... more It had long been believed that the plastic substrates of László Moholy-Nagy's paintings T1 (1926) and Tp 2 (1930) in the collection of the Solomon R. Guggenheim Museum were a phenol formaldehyde resin called Trolitan. Recent investigations using a combination of microscopy and instrumental analysis revealed that these plastics are actually cellulose nitrate filled with a significant proportion of gypsum. The pigments, plasticizers and other organic components were also thoroughly characterized. When considered together with archival information, these characteristics indicate that this material should rather be identified as an industrial plastic called Trolit produced at the same factory as Trolitan: the Rheinisch-Westfälischen Sprengstoff-Fabriken (RWS) in Troisdorf, Germany. This first analytical description of Trolit provides new insights into Moholy-Nagy's unconventional material choices, highlights the remarkably good current condition of the works of art, and shows the importance of using scientific analysis to correctly identify historic plastics instead of relying on trade names for their material identification.
In this paper, we study the problem of automatic identification of pigments applied to paintings ... more In this paper, we study the problem of automatic identification of pigments applied to paintings using hyperspectral reflectance data. Here, we cast the problem of pigment identification in a novel way by decomposing the spectrum into pure pigments. The pure pigment exemplars, chosen and prepared in our laboratory based on historic sources and archaeological examples, closely resemble the materials used to make ancient paintings. To validate our algorithm, we created a set of mock-up paintings in our laboratory consisting of a broad palette of mixtures of pure pigments. Our results clearly demonstrate more accurate estimation of pigment composition than purely distance-based methods such as spectral angle mapping (SAM) and spectral correlation mapping (SCM). In addition, we studied hyperspectral imagery acquired of a Roman-Egyptian portrait, excavated from the site of Tebtunis in the Fayum region of Egypt, and dated to about the 2nd century CE. Using ground truth information obtained using Raman spectroscopy, we show qualitatively that our method accurately detects pigment composition for the specific pigments hematite and indigo.
X-Ray fluorescence (XRF) scanning of works of art is becoming an increasingly popular non-destruc... more X-Ray fluorescence (XRF) scanning of works of art is becoming an increasingly popular non-destructive analytical method. The high quality XRF spectra is necessary to obtain significant information on both major and minor elements used for characterization and provenance analysis. However, there is a trade-off between the spatial resolution of an XRF scan and the Signal-to-Noise Ratio (SNR) of each pixel's spectrum, due to the limited scanning time. In this paper, we propose an XRF image super-resolution method to address this trade-off, thus obtaining a high spatial resolution XRF scan with high SNR. We use a sparse representation of each pixel using a dictionary trained from the spectrum samples of the image, while imposing a spatial smoothness constraint on the sparse coefficients. We then increase the spatial resolution of the sparse coefficient map using a conventional super-resolution method. Finally the high spatial resolution XRF image is reconstructed by the high spatial resolution sparse coefficient map and the trained spectrum dictionary.
A current focus of art conservation research seeks to accurately identify materials, such as oil ... more A current focus of art conservation research seeks to accurately identify materials, such as oil paints or pigments, used in a work of art. Since many of these materials are fluorescent, measuring the fluorescence lifetime following an excitation pulse is a useful non-contact, quantitative method to identify pigments. In this project, we propose a simple method using a dynamic vision sensor to efficiently characterize the fluorescence lifetime of a common pigment named Egyptian Blue, which is consistent with x-ray techniques. We believe our fast, compact and cost-effective method for fluorescence lifetime analysis is useful in art conservation research and potentially a broader range of applications in chemistry and materials science.
In this paper, we propose a streamlined framework of robust 3D acquisition for cultural heritage ... more In this paper, we propose a streamlined framework of robust 3D acquisition for cultural heritage using both photometric stereo and photogrammetric information. An uncalibrated photometric stereo setup is augmented by a synchronized secondary witness camera co-located with a point light source. By recovering the witness camera's position for each exposure with photogrammetry techniques, we estimate the precise 3D location of the light source relative to the photometric stereo camera. We have shown a significant improvement in both light source position estimation and normal map recovery compared to previous uncalibrated photometric stereo techniques. In addition, with the new configuration we propose, we benefit from improved surface shape recovery by jointly incorporating corrected photometric stereo surface normals and a sparse 3D point cloud from photogrammetry.
—Surface shape scanning techniques, such as laser scanning and photometric stereo, are widespread... more —Surface shape scanning techniques, such as laser scanning and photometric stereo, are widespread analytical tools used in the field of cultural heritage. Compared to regular 2D RGB photos, 3D surface scans provide higher fidelity of an object's surface shape which assist conservators, art historians, and archaeologists in understanding how these artworks and artifacts are made and to digitally document them for purposes of conservation. However, current state-of-the-art 3D surface scanning tools used in art conservation are often expensive and bulky-such as light dome structures that are often over 1 m in diameter. In this paper, we introduce mobile shape-from-shifting (SfS): a simple, low-cost and streamlined photometric stereo framework for scanning planar surfaces with a consumer mobile device coupled to a low-cost add-on component. Our free-form mobile SfS framework relaxes the rigorous hardware and other complex requirements inherent to conventional 3D scanning tools. This is achieved by taking a sequence of photos with the on-board camera and flash of a mobile device. The sequence of captures are used to reconstruct high quality normal maps using near-light photometric stereo algorithms, which are of comparable quality to conventional photometric stereo. We demonstrate 3D surface reconstructions with SfS on different materials and scales. Moreover, the mobile SfS technique can be used " in the wild " so that 3D scans may be performed in their natural environment, eliminating the need for transport to a laboratory setting. With the elegant design and low cost, we believe our Mobile SfS can greatly benefit the conservation community by providing a user-friendly and cost-effective solution for 3D surface scanning.
A significant number of oil paintings produced by Georgia O'Keeffe (1887-1986) show surface protr... more A significant number of oil paintings produced by Georgia O'Keeffe (1887-1986) show surface protrusions of varying width, up to several hundreds of microns. These protrusions are similar to those described in the art conservation literature as metallic soaps. Since the presence of these protrusions raises questions about the state of conservation and long-term prospects for deterioration of these artworks, a 3D-imaging technique, photometric stereo using ultraviolet illumination, was developed for the long-term monitoring of the surface-shape of the protrusions and the surrounding paint. Because the UV fluorescence response of painting materials is isotropic, errors typically
Roman‐period mummy portraits are considered to be ancient antecedents of modern portrai-ture. How... more Roman‐period mummy portraits are considered to be ancient antecedents of modern portrai-ture. However, the techniques and materials used in their manufacture are not thoroughly understood. Analytical study of the pigments as well as the binding materials helps to address questions on what aspects of the painting practices originate from Pharaonic and/or Graeco‐Roman traditions, and can aid in determining the provenance of the raw materials from potential locations across the ancient Mediterranean and European worlds. Here, one of the largest assemblages of mummy portraits to remain intact since their excavation from the site of Tebtunis in Egypt was examined using multiple analytical techniques to address how they were made. The archaeological evidence suggests that these portraits were products of a single workshop and, correspondingly, they are found to be made using similar techniques and materials: wax‐based and lead white–rich paint combined with a variety of iron‐based pigments (including hematite, goethite and jarosite), as well as Egyptian blue, minium, indigo and madder lake to create subtle variations and tones.
This paper re-analyses a considerable corpus of glass from the Late Bronze Age site of Nuzi, foun... more This paper re-analyses a considerable corpus of glass from the Late Bronze Age site of Nuzi, found near Kirkuk in Iraq. SEM–WDS and Sr and Nd isotopic analysis were applied, in addition to cataloguing the glass. The work showed that the glass technology at Nuzi was subtly different from contemporary Egyptian sites, using different ways of opacifying and working glass. At least two, perhaps three, Near Eastern production sites are postulated. The range of glass colours and the skill of their application at Nuzi was perhaps not on a par with the Egyptian sites. This led to a reconsideration and review of the accepted wisdom that the Near East is the source of the innovation that is glass-making. This opinion is based on limited textual and iconographic sources and is dominated by an erroneous early date for a very developed Nuzi glass industry along with a few finds of glass vessels in early contexts. Some of this evidence has now been at least questioned, suggesting that glass-making in Egypt, at least as early as the middle of the 15th century BC, and probably earlier, is no later than that in the Near East. It is argued that it is far from clear that the Near East was the source of the innovation and that a more cautious approach would better fit the evidence.
Eremin, K., Degryse, P., Erb-Satullo, N., Ganio, M., Greene, J., Shortland, A., Walton, M., Stage... more Eremin, K., Degryse, P., Erb-Satullo, N., Ganio, M., Greene, J., Shortland, A., Walton, M., Stager, L., 2012. Iron Age glass beads from Carthage, in: Meeks, N.D., Meek, A., Mongiatti, A., Cartwright, C. (Eds.), Historical technology, materials, and conservation: SEM and microanalysis, Archetype Publications and the British Museum, London, pp. 30-35.
– TEM – Focus Ion Beam (FIB) was used to prepare a TEM/APT section at the interface between the C... more – TEM – Focus Ion Beam (FIB) was used to prepare a TEM/APT section at the interface between the Cu-free and Cu-rich zones. The image on the top left corner shows the presence of two Cu nanoparticles within the selected region. Selected area diffraction pattern, top right corner, reveals that the precipitates have face-centered-cubic (fcc) structure. Energy dispersive X-ray spectroscopy detects high concentrations of copper in correspondence of the nanoparticle, while a much lower content is measured in the glass matrix. Opaque red glasses were typically colored by the presence of either a dispersion of nano-sized metallic copper (Cu 0) particles, or dendritic crystals of cuprite, Cu 2 O. To produce either of these phases, the glass furnace conditions were carefully controlled to avoid oxidizing conditions that would cause dissolution of metallic copper and cuprite into the molten glass leading to a blue/green colored glass. The presence of a number of metallic elements beside copper, such as lead, iron, and tin, is considered to be beneficial for the formation of the opaque red color. Whether the particles were added to the melt in a precursor material or grown from the melt in the glass remains unknown. In this study, the methodology proposed encompasses micrometer down to atomic analyses. By studying the composition, crystallographic phases, and defects of the glasses at all scale one can reveal its current physical/mechanical properties and reverse engineer the steps involved in its manufacture. – SEM – The backscatter images show numerous high Z contrast particles, up to 500 nm in size, floating in the glass matrix. The image on the left (300x) informs about the nature of the black areas identified in visible light, showing a different distribution of copper nanoparticles. At higher magnification (2000x), the selected area shows the absence of nano-sized copper from the central area, together with a variation in their sizes: larger particles are located on the border of the Cu-free lentils, their dimensions decreasing by moving more into the glass matrix. – Atom Probe Tomography – The investigation of a copper nanoparticle reveals the presence of a sharp interface separating the relatively pure metallic copper from the soda-lime glass matrix, with a decrease of the Cu concentration from 99.7 at% to about 33 at%. An interdiffusion zone, mostly rich in Cu and Ca, is present, extending from the surface of the copper particle approximately 50 nm into the glass. A detailed analysis of the spatially segmented mass spectra indicates that Cu is additionally enriched in smaller regions within this interdiffusion zone with concentrations up to about 60 at.% Cu, indicative of an interrupted redox reaction involving monovalent copper in a compound similar to cuprite (Cu 2 O). 20 nm
Laser ablation inductively coupled plasma time-of-flight mass spectrometry (LA-ICP-TOFMS) was use... more Laser ablation inductively coupled plasma time-of-flight mass spectrometry (LA-ICP-TOFMS) was used to study the trace element chemistry of coral red and black gloss slip decoration on Greek Attic pottery (6th century BC). The distribution of trace elements in the body fabric and glaze slips were found to be correlated suggesting the raw materials came from a single source. Furthermore, the so-called high calcium and magnesium (HCM) coral red was found to be a less refined material than black gloss, with trace element characteristics suggestive of a carbonate phase in the raw material. This carbonate component may have imparted refractory properties to the HCM coral red slip material during the three-stage oxidative-reductive-oxidative firing used to produce Attic pottery, allowing it to remain porous and re-oxidize during the final firing step, thus creating its final red color. The so-called low calcium and magnesium (LCM) coral red, on the other hand, was found to be more refined ...
Portrait of a Child: Historical and Scientific Studies of a Roman Egyptian Mummy, 2019
Introduction to Portrait of a Child: Historical and Scientific Studies of a Roman Egyptian Mummy,... more Introduction to Portrait of a Child: Historical and Scientific Studies of a Roman Egyptian Mummy, Essi Rönkkö, Taco Terpstra, and Marc Walton eds. (Evanston: Block Museum 2019)
As one of the most desired and expensive artists' materials throughout history, there has long be... more As one of the most desired and expensive artists' materials throughout history, there has long been interest in studying natural lapis lazuli. The traditional method of extracting the blue component, lazurite, from lapis lazuli, as outlined in Cennini's Il Libro dell'Arte, involves a lengthy purification process: (1) finely grind the rock; (2) mix with pine rosin, gum mastic, and beeswax; (3) massage in water to collect the lazurite. Repeating the process produces several grades of the pigment, typically referred to as ultramarine blue. Here, we investigate the sulfur environment within the aluminosilicate framework of lazurite during its extraction from lapis lazuli. The sulfur XANES fingerprint from samples taken at the different stages in Cennini's extraction method were examined. All spectra contain a strong absorption peak at 2483 eV, attributable to sulfate present in the lazurite structure. However, intensity variations appear in the broad envelope of peaks between 2470 and 2475 eV and the pre-peak at 2469.1 eV, indicating a variation in the content of trisulfur (S 3 − ˙) radicals. By studying the effect of each step of Cennini's process, this study elucidates the changes occurring during the extraction and the variability within different grades of the precious coloring material. The increasing application of XANES to the study of artist's materials and works of art motivated extending the research to assess the possibility of X-ray induced damage. Direct comparison of micro-focused and unfo-cused beam experiments suggests an increase of the S 3 − ˙ radicals with prolonged exposure. Analysis indicates that induced damage follows first-order kinetics, providing a first assessment on the acceptable amount of radiation exposure to define the optimal acquisition parameters to allow safe analyses of lapis lazuli and ultramarine pigments.
It had long been believed that the plastic substrates of László Moholy-Nagy's paintings T1 (1926)... more It had long been believed that the plastic substrates of László Moholy-Nagy's paintings T1 (1926) and Tp 2 (1930) in the collection of the Solomon R. Guggenheim Museum were a phenol formaldehyde resin called Trolitan. Recent investigations using a combination of microscopy and instrumental analysis revealed that these plastics are actually cellulose nitrate filled with a significant proportion of gypsum. The pigments, plasticizers and other organic components were also thoroughly characterized. When considered together with archival information, these characteristics indicate that this material should rather be identified as an industrial plastic called Trolit produced at the same factory as Trolitan: the Rheinisch-Westfälischen Sprengstoff-Fabriken (RWS) in Troisdorf, Germany. This first analytical description of Trolit provides new insights into Moholy-Nagy's unconventional material choices, highlights the remarkably good current condition of the works of art, and shows the importance of using scientific analysis to correctly identify historic plastics instead of relying on trade names for their material identification.
In this paper, we study the problem of automatic identification of pigments applied to paintings ... more In this paper, we study the problem of automatic identification of pigments applied to paintings using hyperspectral reflectance data. Here, we cast the problem of pigment identification in a novel way by decomposing the spectrum into pure pigments. The pure pigment exemplars, chosen and prepared in our laboratory based on historic sources and archaeological examples, closely resemble the materials used to make ancient paintings. To validate our algorithm, we created a set of mock-up paintings in our laboratory consisting of a broad palette of mixtures of pure pigments. Our results clearly demonstrate more accurate estimation of pigment composition than purely distance-based methods such as spectral angle mapping (SAM) and spectral correlation mapping (SCM). In addition, we studied hyperspectral imagery acquired of a Roman-Egyptian portrait, excavated from the site of Tebtunis in the Fayum region of Egypt, and dated to about the 2nd century CE. Using ground truth information obtained using Raman spectroscopy, we show qualitatively that our method accurately detects pigment composition for the specific pigments hematite and indigo.
X-Ray fluorescence (XRF) scanning of works of art is becoming an increasingly popular non-destruc... more X-Ray fluorescence (XRF) scanning of works of art is becoming an increasingly popular non-destructive analytical method. The high quality XRF spectra is necessary to obtain significant information on both major and minor elements used for characterization and provenance analysis. However, there is a trade-off between the spatial resolution of an XRF scan and the Signal-to-Noise Ratio (SNR) of each pixel's spectrum, due to the limited scanning time. In this paper, we propose an XRF image super-resolution method to address this trade-off, thus obtaining a high spatial resolution XRF scan with high SNR. We use a sparse representation of each pixel using a dictionary trained from the spectrum samples of the image, while imposing a spatial smoothness constraint on the sparse coefficients. We then increase the spatial resolution of the sparse coefficient map using a conventional super-resolution method. Finally the high spatial resolution XRF image is reconstructed by the high spatial resolution sparse coefficient map and the trained spectrum dictionary.
A current focus of art conservation research seeks to accurately identify materials, such as oil ... more A current focus of art conservation research seeks to accurately identify materials, such as oil paints or pigments, used in a work of art. Since many of these materials are fluorescent, measuring the fluorescence lifetime following an excitation pulse is a useful non-contact, quantitative method to identify pigments. In this project, we propose a simple method using a dynamic vision sensor to efficiently characterize the fluorescence lifetime of a common pigment named Egyptian Blue, which is consistent with x-ray techniques. We believe our fast, compact and cost-effective method for fluorescence lifetime analysis is useful in art conservation research and potentially a broader range of applications in chemistry and materials science.
In this paper, we propose a streamlined framework of robust 3D acquisition for cultural heritage ... more In this paper, we propose a streamlined framework of robust 3D acquisition for cultural heritage using both photometric stereo and photogrammetric information. An uncalibrated photometric stereo setup is augmented by a synchronized secondary witness camera co-located with a point light source. By recovering the witness camera's position for each exposure with photogrammetry techniques, we estimate the precise 3D location of the light source relative to the photometric stereo camera. We have shown a significant improvement in both light source position estimation and normal map recovery compared to previous uncalibrated photometric stereo techniques. In addition, with the new configuration we propose, we benefit from improved surface shape recovery by jointly incorporating corrected photometric stereo surface normals and a sparse 3D point cloud from photogrammetry.
—Surface shape scanning techniques, such as laser scanning and photometric stereo, are widespread... more —Surface shape scanning techniques, such as laser scanning and photometric stereo, are widespread analytical tools used in the field of cultural heritage. Compared to regular 2D RGB photos, 3D surface scans provide higher fidelity of an object's surface shape which assist conservators, art historians, and archaeologists in understanding how these artworks and artifacts are made and to digitally document them for purposes of conservation. However, current state-of-the-art 3D surface scanning tools used in art conservation are often expensive and bulky-such as light dome structures that are often over 1 m in diameter. In this paper, we introduce mobile shape-from-shifting (SfS): a simple, low-cost and streamlined photometric stereo framework for scanning planar surfaces with a consumer mobile device coupled to a low-cost add-on component. Our free-form mobile SfS framework relaxes the rigorous hardware and other complex requirements inherent to conventional 3D scanning tools. This is achieved by taking a sequence of photos with the on-board camera and flash of a mobile device. The sequence of captures are used to reconstruct high quality normal maps using near-light photometric stereo algorithms, which are of comparable quality to conventional photometric stereo. We demonstrate 3D surface reconstructions with SfS on different materials and scales. Moreover, the mobile SfS technique can be used " in the wild " so that 3D scans may be performed in their natural environment, eliminating the need for transport to a laboratory setting. With the elegant design and low cost, we believe our Mobile SfS can greatly benefit the conservation community by providing a user-friendly and cost-effective solution for 3D surface scanning.
A significant number of oil paintings produced by Georgia O'Keeffe (1887-1986) show surface protr... more A significant number of oil paintings produced by Georgia O'Keeffe (1887-1986) show surface protrusions of varying width, up to several hundreds of microns. These protrusions are similar to those described in the art conservation literature as metallic soaps. Since the presence of these protrusions raises questions about the state of conservation and long-term prospects for deterioration of these artworks, a 3D-imaging technique, photometric stereo using ultraviolet illumination, was developed for the long-term monitoring of the surface-shape of the protrusions and the surrounding paint. Because the UV fluorescence response of painting materials is isotropic, errors typically
Roman‐period mummy portraits are considered to be ancient antecedents of modern portrai-ture. How... more Roman‐period mummy portraits are considered to be ancient antecedents of modern portrai-ture. However, the techniques and materials used in their manufacture are not thoroughly understood. Analytical study of the pigments as well as the binding materials helps to address questions on what aspects of the painting practices originate from Pharaonic and/or Graeco‐Roman traditions, and can aid in determining the provenance of the raw materials from potential locations across the ancient Mediterranean and European worlds. Here, one of the largest assemblages of mummy portraits to remain intact since their excavation from the site of Tebtunis in Egypt was examined using multiple analytical techniques to address how they were made. The archaeological evidence suggests that these portraits were products of a single workshop and, correspondingly, they are found to be made using similar techniques and materials: wax‐based and lead white–rich paint combined with a variety of iron‐based pigments (including hematite, goethite and jarosite), as well as Egyptian blue, minium, indigo and madder lake to create subtle variations and tones.
This paper re-analyses a considerable corpus of glass from the Late Bronze Age site of Nuzi, foun... more This paper re-analyses a considerable corpus of glass from the Late Bronze Age site of Nuzi, found near Kirkuk in Iraq. SEM–WDS and Sr and Nd isotopic analysis were applied, in addition to cataloguing the glass. The work showed that the glass technology at Nuzi was subtly different from contemporary Egyptian sites, using different ways of opacifying and working glass. At least two, perhaps three, Near Eastern production sites are postulated. The range of glass colours and the skill of their application at Nuzi was perhaps not on a par with the Egyptian sites. This led to a reconsideration and review of the accepted wisdom that the Near East is the source of the innovation that is glass-making. This opinion is based on limited textual and iconographic sources and is dominated by an erroneous early date for a very developed Nuzi glass industry along with a few finds of glass vessels in early contexts. Some of this evidence has now been at least questioned, suggesting that glass-making in Egypt, at least as early as the middle of the 15th century BC, and probably earlier, is no later than that in the Near East. It is argued that it is far from clear that the Near East was the source of the innovation and that a more cautious approach would better fit the evidence.
Eremin, K., Degryse, P., Erb-Satullo, N., Ganio, M., Greene, J., Shortland, A., Walton, M., Stage... more Eremin, K., Degryse, P., Erb-Satullo, N., Ganio, M., Greene, J., Shortland, A., Walton, M., Stager, L., 2012. Iron Age glass beads from Carthage, in: Meeks, N.D., Meek, A., Mongiatti, A., Cartwright, C. (Eds.), Historical technology, materials, and conservation: SEM and microanalysis, Archetype Publications and the British Museum, London, pp. 30-35.
– TEM – Focus Ion Beam (FIB) was used to prepare a TEM/APT section at the interface between the C... more – TEM – Focus Ion Beam (FIB) was used to prepare a TEM/APT section at the interface between the Cu-free and Cu-rich zones. The image on the top left corner shows the presence of two Cu nanoparticles within the selected region. Selected area diffraction pattern, top right corner, reveals that the precipitates have face-centered-cubic (fcc) structure. Energy dispersive X-ray spectroscopy detects high concentrations of copper in correspondence of the nanoparticle, while a much lower content is measured in the glass matrix. Opaque red glasses were typically colored by the presence of either a dispersion of nano-sized metallic copper (Cu 0) particles, or dendritic crystals of cuprite, Cu 2 O. To produce either of these phases, the glass furnace conditions were carefully controlled to avoid oxidizing conditions that would cause dissolution of metallic copper and cuprite into the molten glass leading to a blue/green colored glass. The presence of a number of metallic elements beside copper, such as lead, iron, and tin, is considered to be beneficial for the formation of the opaque red color. Whether the particles were added to the melt in a precursor material or grown from the melt in the glass remains unknown. In this study, the methodology proposed encompasses micrometer down to atomic analyses. By studying the composition, crystallographic phases, and defects of the glasses at all scale one can reveal its current physical/mechanical properties and reverse engineer the steps involved in its manufacture. – SEM – The backscatter images show numerous high Z contrast particles, up to 500 nm in size, floating in the glass matrix. The image on the left (300x) informs about the nature of the black areas identified in visible light, showing a different distribution of copper nanoparticles. At higher magnification (2000x), the selected area shows the absence of nano-sized copper from the central area, together with a variation in their sizes: larger particles are located on the border of the Cu-free lentils, their dimensions decreasing by moving more into the glass matrix. – Atom Probe Tomography – The investigation of a copper nanoparticle reveals the presence of a sharp interface separating the relatively pure metallic copper from the soda-lime glass matrix, with a decrease of the Cu concentration from 99.7 at% to about 33 at%. An interdiffusion zone, mostly rich in Cu and Ca, is present, extending from the surface of the copper particle approximately 50 nm into the glass. A detailed analysis of the spatially segmented mass spectra indicates that Cu is additionally enriched in smaller regions within this interdiffusion zone with concentrations up to about 60 at.% Cu, indicative of an interrupted redox reaction involving monovalent copper in a compound similar to cuprite (Cu 2 O). 20 nm
In this thesis, the fabrication technology of Roman lead glazes were examined using a number of m... more In this thesis, the fabrication technology of Roman lead glazes were examined using a number of materials science techniques: namely, electron probe microanalysis, X-ray diffraction, and inductively coupled plasma atomic emission spectroscopy. The overall aim of this work was to discern particular technological styles for a wide group of lead glazes by quantifying the chemical and microstructural features of glaze production. Using experimental replication, it was found that two basic methods of glazing could be identified chemically. When applying PbO alone to an earthenware ceramic, the resulting glaze was in equilibrium with the ceramic as indicated by flat compositional profiles obtained along the glaze cross-section. However, when applying PbO·SiO2 mixtures to earthenware ceramics, gradient profiles indicative of diffusive mass transfer were obtained from the glaze cross-section. On the basis of these chemical criteria, these two methods of glazing were identified in archaeological
material. It has been determined that the earliest lead glazes from Anatolia and Italy (approximately 1st century B.C.) were made using PbO·SiO2 mixtures applied to calcareous clays with Fe and Cu oxides added as colourants. Later production (post 2nd century A.D.), seems to have employed PbO alone applied to non-calcareous clays with no intentionally added colourants. The Roman production of lead glazes was compared to both those of Late Antiquity (4th – 10th centuries A.D.) which continued to use PbO applied to non-calcareous clays, and to those of Byzantine and Islamic contexts (8th – 14th centuries A.D.) which seem to have used PbO·SiO2 mixtures applied to both calcareous and non-calcareous clays. It is also argued that the technological features of the Byzantine and Islamic glaze production shared more in common with the contemporary Chinese lead glazing tradition (the Sancai wares of
the 7th century A.D.) which also used PbO·SiO2 mixtures applied to non-calcareous clays, than with the Late Antique glazing tradition.
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material. It has been determined that the earliest lead glazes from Anatolia and Italy (approximately 1st century B.C.) were made using PbO·SiO2 mixtures applied to calcareous clays with Fe and Cu oxides added as colourants. Later production (post 2nd century A.D.), seems to have employed PbO alone applied to non-calcareous clays with no intentionally added colourants. The Roman production of lead glazes was compared to both those of Late Antiquity (4th – 10th centuries A.D.) which continued to use PbO applied to non-calcareous clays, and to those of Byzantine and Islamic contexts (8th – 14th centuries A.D.) which seem to have used PbO·SiO2 mixtures applied to both calcareous and non-calcareous clays. It is also argued that the technological features of the Byzantine and Islamic glaze production shared more in common with the contemporary Chinese lead glazing tradition (the Sancai wares of
the 7th century A.D.) which also used PbO·SiO2 mixtures applied to non-calcareous clays, than with the Late Antique glazing tradition.