Institute of Archaeology, Czech Academy of Sciences, Natural Sciences and Archaeometry, Associate scientist/archaeometry-conservation sciences, lecturer of conservation sciences (Unesco, Charles University, Prague, Institute of Chemical Technology Prague, Leon Levy Foundation), field conservator (Ulug Depe Turkmenistan, Mentesh Tepe Azerbaijan)
Phone: 00 420 266 009 291 Address: Institute of Archaeology of the Academy of Sciences of the Czech Republic, Prague, v.v.í, Letenská 4, 118 01 Praha 1
The study of ancient gilding is often problematic, as the gilding layers are soft and prone to de... more The study of ancient gilding is often problematic, as the gilding layers are soft and prone to deformation during sample preparation. In this respect, focused ion beam (FIB) milling on a field emission gun scanning electron microscope (FEG-SEM) provides poorly invasive in situ sampling. The operating process is here detailed and applied on gilded medieval copper-based elite jewellery (10th century) from Prague Castle. Obtained crosssections and slices of gilded samples were investigated up to nanometer scale without gilding layer deformation. By coupling structural observation with elemental X-ray analysis (EDS) and electron beam diffraction (EBSD), FIB FEG-SEM provided new data on the physical-chemical characteristics of the gilded layer. The gilding has a two-layer metallurgical structure containing a quaternary Au (Hg, Cu, Ag) alloy corresponding to the gold solid solution fcc phase, and a submicrometric inner sublayer formed by a Au-Cu phase, relative to the interdiffusion of copper from the substrate during the fire gilding process. The applied temperature for gilding can be estimated at c. 400 • C. Sintering of the mercury-gold amalgam globules during the fire heating is highlighted. The precise characterisation of the gilding layers provided useful comparative parameters for identifying fire gilding skill levels and assessing the overall quality of the archaeological pieces.
The study of ancient gilding is often problematic, as the gilding layers are soft and prone to de... more The study of ancient gilding is often problematic, as the gilding layers are soft and prone to deformation during sample preparation. In this respect, focused ion beam (FIB) milling on a field emission gun scanning electron microscope (FEG-SEM) provides poorly invasive in situ sampling. The operating process is here detailed and applied on gilded medieval copper-based elite jewellery (10th century) from Prague Castle. Obtained crosssections and slices of gilded samples were investigated up to nanometer scale without gilding layer deformation. By coupling structural observation with elemental X-ray analysis (EDS) and electron beam diffraction (EBSD), FIB FEG-SEM provided new data on the physical-chemical characteristics of the gilded layer. The gilding has a two-layer metallurgical structure containing a quaternary Au (Hg, Cu, Ag) alloy corresponding to the gold solid solution fcc phase, and a submicrometric inner sublayer formed by a Au-Cu phase, relative to the interdiffusion of copper from the substrate during the fire gilding process. The applied temperature for gilding can be estimated at c. 400 • C. Sintering of the mercury-gold amalgam globules during the fire heating is highlighted. The precise characterisation of the gilding layers provided useful comparative parameters for identifying fire gilding skill levels and assessing the overall quality of the archaeological pieces.
The study presents a LT C1 sword in its scabbard from grave 8 of Záluží (Central Bohemia), excava... more The study presents a LT C1 sword in its scabbard from grave 8 of Záluží (Central Bohemia), excavated by the Town Museum of Čelákovice. The sword was lifted in situ and transported for restoration to the laboratory of the Institute of Archaeology in Prague where it underwent meticulous micro‑excavations and documentation. X–ray radiography, X–ray computed tomography and mechanical cleaning highlighted two or three successive steps in the creation of a complex and unique ornament on the scabbard: first an engraved dragon pair adorned the front plate. Later, it was decorated with non-ferrous incrustations without consideration of the previous engraved ornament. The succession of the two different types of scabbard ornamentation is analyzed in the light of the archaeological context and anthropological observations.
Gilded copper hollow spherical pendants known as gombiky (s. gombik) were examined to identify th... more Gilded copper hollow spherical pendants known as gombiky (s. gombik) were examined to identify the technology of gilding and the material chosen as the substrate. The examined ornaments dating from the ninth and tenth centuries AD were recovered from elite graves of two major political, ecclesiastical and economic centres of the Early Medieval period located in the territory of the present-day Czech Republic: Mikulčice and Prague Castle, major sites of Moravia and Bohemia, respectively. Taking into account the state of degradation and possible bias due to earlier restorations, surface and bulk characterisation of the gilded material has been performed combining optical observation, X-ray radiography, metallography, scanning electron microscopy with energy-dispersive spectrometry (SEM/EDS analysis) and focused ion beam (FIB) milling mounted on FEG-SEM. The manufacturing procedure was reproduced by experimental archaeology. A detailed investigation of the gilded artefacts revealed several types of gombik construction involving different mounted elements, including the main body parts and the suspension system elements joined by hard soldering. The different constitutive parts are made with almost pure copper or low-purity copper. The systematic use of fire gilding (mercury amalgam gilding) was documented. Differences in the materials that were used and technical quality show the coexistence of finely produced objects by highly skilled and knowledgeable jewellers alongside more coarsely manufactured imitations. These variations are discussed in terms of different workshops in a possible relationship with their origin of manufacture.
Proceedings of the 5th International Conference "Archaeometallurgy in Europe", 19-21 June 2019, Miskolc, Hungary, 2021
This paper deals with the archaeological context, function, typology and technological study of a... more This paper deals with the archaeological context, function, typology and technological study of a type of spherical hollow pendants termed gombiky (sg. gombik), which were worn by members of the Moravian elite in the 9th century AD. The gombiky were recovered in elite graves from Mikulčice – one of the major central places of Great Moravia. The archaeological context, occurrence in graves and function of these enigmatic objects are discussed. Their typology and construction based on their decoration technique are presented. In order to determine the metal composition, construction, and manufacturing processes of these types of ornaments, several specimens were investigated by stereomicroscopy (Olympus SZ60), X-ray radiography and scanning electron microscopy (SEM), supplemented by electron microanalysis (EDS). Replicas of each main type of gombik were manufactured by a professional goldsmith to understand the different stages of manufacture and soldering techniques. The results have evidenced the use of high purity gold alloys, silver alloys, gilded copper, different types of soldering techniques (fusion welding, hard solder), fire-gilding, specific tool marks and masterful chasing, filigree and granulation. The research provided a better understanding of the materials, the construction, manufacturing and soldering techniques and the stages of fabrication of this type of jewellery.
The Triangle cemetery in Prague-Střešovice was the only preserved part of the great burial site f... more The Triangle cemetery in Prague-Střešovice was the only preserved part of the great burial site from the 9 th-10 th century AD; this site was partially destroyed beginning in the 18 th century by the extraction of clay for the Strahov brick factory. A total of 49 graves, all dated to the 10 th century, were uncovered in the preserved part of the cemetery in 2012. Children's grave no. 16 was the richest of the children's graves and the second richest of all graves in the cemetery. A total of 19 silver jewels were found in the grave: kaptorga-amulet container, beads, hollow spherical pendants-gombiks. A technical study was performed to describe the construction of the different types of jewels and identify the material used to manufacture them. The arte facts were examined with a stereomicroscope, subjected to X-ray radiography and observed and analysed with scanning electron microscopy coupled with energy-dispersive X-ray spectrometry (SEM/EDS). A replica provided practical information about the time of realisation of each type of jewel. Analogies from the technical and thematic points of view were further searched. The set of jewellery comes from the production of the Prague workshop which enriched the tradition of Great Moravian jewellery with new elements inspired by cultural influences from the west, east and south.
Gilded copper hollow spherical pendants known as gombiky (s. gombik) were examined to identify th... more Gilded copper hollow spherical pendants known as gombiky (s. gombik) were examined to identify the technology of gilding and the material chosen as the substrate. The examined ornaments dating from the ninth and tenth centuries AD were recovered from elite graves of two major political, ecclesiastical and economic centres of the Early Medieval period located in the territory of the present-day Czech Republic: Mikulčice and Prague Castle, major sites of Moravia and Bohemia, respectively. Taking into account the state of degradation and possible bias due to earlier restorations, surface and bulk characterisation of the gilded material has been performed combining optical observation, X-ray radiography, metallography, scanning electron microscopy with energy-dispersive spectrometry (SEM/EDS analysis) and focused ion beam (FIB) milling mounted on FEG-SEM. The manufacturing procedure was reproduced by experimental archaeology. A detailed investigation of the gilded artefacts revealed several types of gombik construction involving different mounted elements, including the main body parts and the suspension system elements joined by hard soldering. The different constitutive parts are made with almost pure copper or low-purity copper. The systematic use of fire gilding (mercury amalgam gilding) was documented. Differences in the materials that were used and technical quality show the coexistence of finely produced objects by highly skilled and knowledgeable jewellers alongside more coarsely manufactured imitations. These variations are discussed in terms of different workshops in a possible relationship with their origin of manufacture.
In response to the scholar debate regarding the way in which Great Moravian spherical buttons wer... more In response to the scholar debate regarding the way in which Great Moravian spherical buttons were used, this study presents an overview of specimens whose use may be inferred on the basis of the archaeological context. The topic is demonstrated using two case studies, where the function of the spherical buttons may be definitively proved thanks to preserved textile fibres. Textile and metal material characterization was performed by EDS analysis on SEM. The case studies are accompanied by analogous finds known from the literature. In conclusion, we propose possible interpretations of the functional range of spherical hollow buttons.
The study of ancient gilding is often problematic, as the gilding layers are soft and prone to de... more The study of ancient gilding is often problematic, as the gilding layers are soft and prone to deformation during sample preparation. In this respect, focused ion beam (FIB) milling on a field emission gun scanning electron microscope (FEG-SEM) provides poorly invasive in situ sampling. The operating process is here detailed and applied on gilded medieval copper-based elite jewellery (10th century) from Prague Castle. Obtained crosssections and slices of gilded samples were investigated up to nanometer scale without gilding layer deformation. By coupling structural observation with elemental X-ray analysis (EDS) and electron beam diffraction (EBSD), FIB FEG-SEM provided new data on the physical-chemical characteristics of the gilded layer. The gilding has a two-layer metallurgical structure containing a quaternary Au (Hg, Cu, Ag) alloy corresponding to the gold solid solution fcc phase, and a submicrometric inner sublayer formed by a Au-Cu phase, relative to the interdiffusion of copper from the substrate during the fire gilding process. The applied temperature for gilding can be estimated at c. 400 • C. Sintering of the mercury-gold amalgam globules during the fire heating is highlighted. The precise characterisation of the gilding layers provided useful comparative parameters for identifying fire gilding skill levels and assessing the overall quality of the archaeological pieces.
The study of ancient gilding is often problematic, as the gilding layers are soft and prone to de... more The study of ancient gilding is often problematic, as the gilding layers are soft and prone to deformation during sample preparation. In this respect, focused ion beam (FIB) milling on a field emission gun scanning electron microscope (FEG-SEM) provides poorly invasive in situ sampling. The operating process is here detailed and applied on gilded medieval copper-based elite jewellery (10th century) from Prague Castle. Obtained crosssections and slices of gilded samples were investigated up to nanometer scale without gilding layer deformation. By coupling structural observation with elemental X-ray analysis (EDS) and electron beam diffraction (EBSD), FIB FEG-SEM provided new data on the physical-chemical characteristics of the gilded layer. The gilding has a two-layer metallurgical structure containing a quaternary Au (Hg, Cu, Ag) alloy corresponding to the gold solid solution fcc phase, and a submicrometric inner sublayer formed by a Au-Cu phase, relative to the interdiffusion of copper from the substrate during the fire gilding process. The applied temperature for gilding can be estimated at c. 400 • C. Sintering of the mercury-gold amalgam globules during the fire heating is highlighted. The precise characterisation of the gilding layers provided useful comparative parameters for identifying fire gilding skill levels and assessing the overall quality of the archaeological pieces.
The study presents a LT C1 sword in its scabbard from grave 8 of Záluží (Central Bohemia), excava... more The study presents a LT C1 sword in its scabbard from grave 8 of Záluží (Central Bohemia), excavated by the Town Museum of Čelákovice. The sword was lifted in situ and transported for restoration to the laboratory of the Institute of Archaeology in Prague where it underwent meticulous micro‑excavations and documentation. X–ray radiography, X–ray computed tomography and mechanical cleaning highlighted two or three successive steps in the creation of a complex and unique ornament on the scabbard: first an engraved dragon pair adorned the front plate. Later, it was decorated with non-ferrous incrustations without consideration of the previous engraved ornament. The succession of the two different types of scabbard ornamentation is analyzed in the light of the archaeological context and anthropological observations.
Gilded copper hollow spherical pendants known as gombiky (s. gombik) were examined to identify th... more Gilded copper hollow spherical pendants known as gombiky (s. gombik) were examined to identify the technology of gilding and the material chosen as the substrate. The examined ornaments dating from the ninth and tenth centuries AD were recovered from elite graves of two major political, ecclesiastical and economic centres of the Early Medieval period located in the territory of the present-day Czech Republic: Mikulčice and Prague Castle, major sites of Moravia and Bohemia, respectively. Taking into account the state of degradation and possible bias due to earlier restorations, surface and bulk characterisation of the gilded material has been performed combining optical observation, X-ray radiography, metallography, scanning electron microscopy with energy-dispersive spectrometry (SEM/EDS analysis) and focused ion beam (FIB) milling mounted on FEG-SEM. The manufacturing procedure was reproduced by experimental archaeology. A detailed investigation of the gilded artefacts revealed several types of gombik construction involving different mounted elements, including the main body parts and the suspension system elements joined by hard soldering. The different constitutive parts are made with almost pure copper or low-purity copper. The systematic use of fire gilding (mercury amalgam gilding) was documented. Differences in the materials that were used and technical quality show the coexistence of finely produced objects by highly skilled and knowledgeable jewellers alongside more coarsely manufactured imitations. These variations are discussed in terms of different workshops in a possible relationship with their origin of manufacture.
Proceedings of the 5th International Conference "Archaeometallurgy in Europe", 19-21 June 2019, Miskolc, Hungary, 2021
This paper deals with the archaeological context, function, typology and technological study of a... more This paper deals with the archaeological context, function, typology and technological study of a type of spherical hollow pendants termed gombiky (sg. gombik), which were worn by members of the Moravian elite in the 9th century AD. The gombiky were recovered in elite graves from Mikulčice – one of the major central places of Great Moravia. The archaeological context, occurrence in graves and function of these enigmatic objects are discussed. Their typology and construction based on their decoration technique are presented. In order to determine the metal composition, construction, and manufacturing processes of these types of ornaments, several specimens were investigated by stereomicroscopy (Olympus SZ60), X-ray radiography and scanning electron microscopy (SEM), supplemented by electron microanalysis (EDS). Replicas of each main type of gombik were manufactured by a professional goldsmith to understand the different stages of manufacture and soldering techniques. The results have evidenced the use of high purity gold alloys, silver alloys, gilded copper, different types of soldering techniques (fusion welding, hard solder), fire-gilding, specific tool marks and masterful chasing, filigree and granulation. The research provided a better understanding of the materials, the construction, manufacturing and soldering techniques and the stages of fabrication of this type of jewellery.
The Triangle cemetery in Prague-Střešovice was the only preserved part of the great burial site f... more The Triangle cemetery in Prague-Střešovice was the only preserved part of the great burial site from the 9 th-10 th century AD; this site was partially destroyed beginning in the 18 th century by the extraction of clay for the Strahov brick factory. A total of 49 graves, all dated to the 10 th century, were uncovered in the preserved part of the cemetery in 2012. Children's grave no. 16 was the richest of the children's graves and the second richest of all graves in the cemetery. A total of 19 silver jewels were found in the grave: kaptorga-amulet container, beads, hollow spherical pendants-gombiks. A technical study was performed to describe the construction of the different types of jewels and identify the material used to manufacture them. The arte facts were examined with a stereomicroscope, subjected to X-ray radiography and observed and analysed with scanning electron microscopy coupled with energy-dispersive X-ray spectrometry (SEM/EDS). A replica provided practical information about the time of realisation of each type of jewel. Analogies from the technical and thematic points of view were further searched. The set of jewellery comes from the production of the Prague workshop which enriched the tradition of Great Moravian jewellery with new elements inspired by cultural influences from the west, east and south.
Gilded copper hollow spherical pendants known as gombiky (s. gombik) were examined to identify th... more Gilded copper hollow spherical pendants known as gombiky (s. gombik) were examined to identify the technology of gilding and the material chosen as the substrate. The examined ornaments dating from the ninth and tenth centuries AD were recovered from elite graves of two major political, ecclesiastical and economic centres of the Early Medieval period located in the territory of the present-day Czech Republic: Mikulčice and Prague Castle, major sites of Moravia and Bohemia, respectively. Taking into account the state of degradation and possible bias due to earlier restorations, surface and bulk characterisation of the gilded material has been performed combining optical observation, X-ray radiography, metallography, scanning electron microscopy with energy-dispersive spectrometry (SEM/EDS analysis) and focused ion beam (FIB) milling mounted on FEG-SEM. The manufacturing procedure was reproduced by experimental archaeology. A detailed investigation of the gilded artefacts revealed several types of gombik construction involving different mounted elements, including the main body parts and the suspension system elements joined by hard soldering. The different constitutive parts are made with almost pure copper or low-purity copper. The systematic use of fire gilding (mercury amalgam gilding) was documented. Differences in the materials that were used and technical quality show the coexistence of finely produced objects by highly skilled and knowledgeable jewellers alongside more coarsely manufactured imitations. These variations are discussed in terms of different workshops in a possible relationship with their origin of manufacture.
In response to the scholar debate regarding the way in which Great Moravian spherical buttons wer... more In response to the scholar debate regarding the way in which Great Moravian spherical buttons were used, this study presents an overview of specimens whose use may be inferred on the basis of the archaeological context. The topic is demonstrated using two case studies, where the function of the spherical buttons may be definitively proved thanks to preserved textile fibres. Textile and metal material characterization was performed by EDS analysis on SEM. The case studies are accompanied by analogous finds known from the literature. In conclusion, we propose possible interpretations of the functional range of spherical hollow buttons.
Integrating a multidisciplinary methodology, the technological approach developed in this publica... more Integrating a multidisciplinary methodology, the technological approach developed in this publication provides new insights into Great Moravian and Bohemian elite jewellery dated from the 9th and 10th centuries AD. Based on an investigation of the main types of jewels (gombiky, earrings, metallic elements of necklaces including kaptorgy, beads, and chains), it sheds light on the complex construction of these jewels, on the different manufacturing processes, and on the decoration techniques involved in their fabrication. Detailed material characterizations highlight the elemental chemical composition and purity of the alloys used by the jewellers in both regions and over time. The comparisons of the size, the total number of components, the estimated manufacturing time, and the weight of precious metal needed to produce each type of jewel shed light on the level of complexity involved in their manufacture and highlight the exceptional pieces. The observations and comparisons of tool marks, defects, and quality of realization evidence the presence of very fine pieces manufactured by highly skilled goldsmiths using sophisticated tools alongside coarse productions manufactured by unexperienced craftsmen with low skill and more rudimentary tools. In addition, they allow us to identify pieces likely produced in the same workshop and probable imports.
This booklet is addressed to the trainees of the Leon Levy Archaeological Restoration Laboratory ... more This booklet is addressed to the trainees of the Leon Levy Archaeological Restoration Laboratory in Dushak (Turkmenistan) who participated in the training course, but also any other institutions and museums in Turkmenistan and Central Asia interested in the conservation of ceramics. It provides a basic theoritical knowledge about ceramic material, its deterioration and conservation, and also an illustrated section concerning the different stages of conservation and restoration of archaeological ceramics. This booklet represents the theoretical background to practical work undertaken by the trainees during the course.
Metal 2022, proceedings of the interim meeting of the ICOM-CC Metals working group, 2022
Focussed ion beam (FIB) mounted on a scanning electron microscope with a field emission gun (FEG-... more Focussed ion beam (FIB) mounted on a scanning electron microscope with a field emission gun (FEG-SEM) offers new perspectives in studies of soft, multilayered metal artefacts. In addition to conventional observation, the system allows cross-sections to be made in situ, that is, within the SEM chamber, using the FIB to mill the selected surface and thus obtain a local cross-section up to 100 to 200 μm wide and 10 to 20 μm deep. This new method of investigation is of particular interest in the study of precious cultural heritage artefacts, for which sampling is often problematic. Unlike classical metallography, the accurate cross-sections obtained with FIB on FEG-SEM avoid damage to multilayered materials, as ionic ablation does not deform the soft layers. The technique is therefore particularly useful for observing and characterising gilded artefacts. After surface milling, detailed structural information can be obtained at the nanometre scale and used in further analyses. Applied here on hollow gilded copper alloy pendants (known as gombiky) from Prague Castle, dated from the 10th century AD, FIB on FEG-SEM yielded new and accurate information regarding the thickness, porosity, metallurgical structure and general condition of these complex artefacts. The method aims to provide new parameters for drawing comparisons between fine products produced by highly skilled jewellers and coarse imitations made by less-experienced craftsmen.
Conference The Celts 2022 Mikulov, Czech Republic, 2022
During rescue excavations, nine LT graves were unearthed over a 35 × 85 m area by the archaeologi... more During rescue excavations, nine LT graves were unearthed over a 35 × 85 m area by the archaeological staff of the Čelákovice Town Museum. The graves belong to an average cemetery dated mainly to the 3rd century BC. All the burials are inhumations, oriented NNE-SSW, and they all contained grave goods. Five graves held only one or two iron brooches and/or bronze armlets, but in four particularly interesting cases, a rich material was found. Grave 7 (Fig.1) and 8 (Fig. 2) held both a warrior with a complete war gear: a sword in an iron scabbard with a chain, a shield with an iron frame and an umbo and a spear with an iron butt. The swords and the spears were placed on the right side, near the arm of the deceased. The shields were probably placed on the side near the feet, on the left (grave 7) or on the right side (grave 8) of the warrior. As dress accessories, we found iron brooches in both cases and a tubular iron armlet on the left upper arm in grave 8.
Mikulčice and Prague Castle, located in the territory of present-day Czech Republic, were two of ... more Mikulčice and Prague Castle, located in the territory of present-day Czech Republic, were two of the major political, ecclesiastical and economic centres of the Early Medieval Period. Mikulčice was probably the seat of the Moravian ruler and the capital of Great Moravia, the first Slavic pre-state, while Prague Castle became the main seat of the Bohemian rulers at the turn of the tenth century after the fall of the Moravian Empire. A high concentration of prestigious grave goods belonging to the Moravian and Bohemian ruling elite has been discovered in both localities. Among the more notable finds are spherical hollow buttons known as gombiky (used as prestigious clothing fasteners or pendants) as well as luxurious amulets (usually in pairs) mainly found in children’s graves but also in adult male and female graves. To better understand these objects and to trace the production of specific workshops, a technical study was carried out to determine the metal composition of the items as well as the construction and manufacturing processes involved.
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Papers by Estelle Ottenwelter
this study presents an overview of specimens whose use may be inferred on the basis of the archaeological
context. The topic is demonstrated using two case studies, where the function of the spherical buttons may be
definitively proved thanks to preserved textile fibres. Textile and metal material characterization was performed
by EDS analysis on SEM. The case studies are accompanied by analogous finds known from the literature.
In conclusion, we propose possible interpretations of the functional range of spherical hollow buttons.
this study presents an overview of specimens whose use may be inferred on the basis of the archaeological
context. The topic is demonstrated using two case studies, where the function of the spherical buttons may be
definitively proved thanks to preserved textile fibres. Textile and metal material characterization was performed
by EDS analysis on SEM. The case studies are accompanied by analogous finds known from the literature.
In conclusion, we propose possible interpretations of the functional range of spherical hollow buttons.
Detailed material characterizations highlight the elemental chemical composition and purity of the alloys used by the jewellers in both regions and over time. The comparisons of the size, the total number of components, the estimated manufacturing time, and the weight of precious metal needed to produce each type of jewel shed light on the level of complexity involved in their manufacture and highlight the exceptional pieces. The observations and comparisons of tool marks, defects, and quality of realization evidence the presence of very fine pieces manufactured by highly skilled goldsmiths using sophisticated tools alongside coarse productions manufactured by unexperienced craftsmen with low skill and more rudimentary tools. In addition, they allow us to identify pieces likely produced in the same workshop and probable imports.
illustrated section concerning the different stages of conservation and restoration of archaeological ceramics. This booklet represents the theoretical background to practical work undertaken by the trainees during the course.