Conservator-restorer and Expert in violin family instruments. Researches on historical varnishes, violin-making history. Phone: +33145389070 Address: Atelier Cels 7 rue Cels 75014 Paris France
The historical varnish technology is of interest to various fields in cultural heritage. To under... more The historical varnish technology is of interest to various fields in cultural heritage. To understand the material properties of these historic surface coatings it is important to get insight in the technological background, i.e. the relationship between the material and the processing method. This study has specif- ically focused on the use of pumice stone and bone ash often mentioned in historical sources as driers for oil-based coating systems. For this purpose lute and Italian violins from the period between the 16th to the mid 18th century were examined. Both, the main organic composition of the varnish and the addition of mineral additives were considered. Based on the analytical data and the corresponding information from historical written sources, the siccativation of oil-based varnishes with pumice stone and bone ash was simulated experimentally. The results of these reconstructions confirm that the technological know-how behind these varnishes is far more complex than it may appear at first glance and that the organic and inorganic components must be regarded as a balanced technological system where each of the various components has a specific function. In this context, these inorganic additives effectively induced accel- erated drying, improved the mechanical film properties of young films and showed a stabilizing effect on the long-term degradation during aging.
Abstract Infrared spectroscopy (FTIR) is a standard technique for the characterisation of organic... more Abstract Infrared spectroscopy (FTIR) is a standard technique for the characterisation of organic materials in conservation science. This analytical technique is particularly interesting to analyse historical varnishes from cultural artefacts, as only minute samples are required. Some limitations apply, however, when analysing such chemically complex multi-component materials with interfering absorption bands. A previously introduced sample pre-treatment method using gaseous sulfur tetrafluoride SF 4 has shown to widen the application fields of the IR-technique by improving its specificity. One of these new fields is its successful application to the characterisation of complex aged natural varnish and lacquer systems. The fluorination treatment leads to characteristic band shifts of four individual saturated and unsaturated acid groups attached at varying positions of the terpene backbone. This allows the separation of otherwise overlapping carbonyl bands of different ketones and ester groups. Based on this technique, inert and unique functional groups can be used as material specific markers to identify drying oil, shellac and different terpene resins in varnishes and lacquers. The proposed markers proved to be stable for several hundred years. These findings are particularly interesting, as it is now possible to trace such markers even in very old varnishes dating back to the 16th century – with a likewise simple technique.
The inclusion of minerals in Italian varnishes from the 16th to mid-18th centuries has long been ... more The inclusion of minerals in Italian varnishes from the 16th to mid-18th centuries has long been a source of speculation. Analysis of micro-samples from multiple locations on 30 reference instruments from the 16th to the mid-18th century as well as a comprehensive study of written sources have revealed a centuries-old tradition of using pumice stone and calcined bones as additives for oil varnishes. These new findings represent a paradigm shift in our understanding of historical varnishes and open up exciting new perspectives.
JEAN-PHILIPPE ECHARD and BALTHAZAR SOULIER reveal the results of their seven-year research into S... more JEAN-PHILIPPE ECHARD and BALTHAZAR SOULIER reveal the results of their seven-year research into Stradivari's varnish, using five of the master's instruments from Paris's Musée de la Musique
The historical varnish technology is of interest to various fields in cultural heritage. To under... more The historical varnish technology is of interest to various fields in cultural heritage. To understand the material properties of these historic surface coatings it is important to get insight in the technological background, i.e. the relationship between the material and the processing method. This study has specifically focused on the use of pumice stone and bone ash often mentioned in historical sources as driers for oil-based coating systems. For this purpose lute and Italian violins from the period between the 16 th to the mid 18 th century were examined. Both, the main organic composition of the varnish and the addition of mineral additives were considered. Based on the analytical data and the corresponding information from historical written sources, the siccativation of oil-based varnishes with pumice stone and bone ash was simulated experimentally. The results of these reconstructions confirm that the technological know-how behind these varnishes is far more complex than it may appear at first glance and that the organic and inorganic components must be regarded as a balanced technological system where each of the various components has a specific function. In this context, these inorganic additives effectively induced accelerated drying, improved the mechanical film properties of young films and showed a stabilizing effect on the long-term degradation during aging.
Infrared spectroscopy (FTIR) is a standard technique for the characterisation of organic material... more Infrared spectroscopy (FTIR) is a standard technique for the characterisation of organic materials in conservation science. This analytical technique is particularly interesting to analyse historical varnishes from cultural artefacts, as only minute samples are required. Some limitations apply, however, when analysing such chemically complex multi-component materials with interfering absorption bands. A previously introduced sample pre-treatment method using gaseous sulfur tetrafluoride SF4 has shown to widen the application fields of the IR-technique by improving its specificity. One of these new fields is its successful application to the characterisation of complex aged natural varnish and lacquer systems. The fluorination treatment leads to characteristic band shifts of four individual saturated and unsaturated acid groups attached at varying positions of the terpene backbone. This allows the separation of otherwise overlapping carbonyl bands of different ketones and ester groups. Based on this technique, inert and unique functional groups can be used as material specific markers to identify drying oil, shellac and different terpene resins in varnishes and lacquers. The proposed markers proved to be stable for several hundred years. These findings are particularly interesting, as it is now possible to trace such markers even in very old varnishes dating back to the 16th century – with a likewise simple technique.
The study of varnishes from musical instruments presents the difficulty of analysing very thin la... more The study of varnishes from musical instruments presents the difficulty of analysing very thin layers of heterogeneous materials on samples most of which are generally brittle and difficult to prepare. Such study is crucial to the understanding of historical musical instrument varnishing practices since written sources before 1800 are very rare and not precise. Fourier-transform infrared (FTIR) spectroscopy and imaging methods were applied to identify the major chemical components within the build-up of the varnish layers on a cello made by one of the most prominent French violin-makers of the eighteenth century (Jacques Boquay, ca. 1680–1730). Two types of FTIR imaging methods were used: scanning with a synchrotron-based microscope and full-field imaging using a 2D imager with a conventional source. An interpretation of the results obtained from these studies on the Boquay cello is that the maker first applied a proteinaceous layer, probably gelatine-based animal glue. He later applied a second layer based on a mixture of a drying oil and diterpenic resin from Pinaceae sp. From an historical perspective, the results complement previous studies by describing a second technique used for musical instrument finishes at the beginning of the eighteenth century in Europe. Figure FTIR spectromicroscopy study of a cello made by the luthier Jacques Boquay (Paris, ca. 1680-1729) shows that the maker first applied a proteinaceous layer, probably gelatine-based animal glue.
The historical varnish technology is of interest to various fields in cultural heritage. To under... more The historical varnish technology is of interest to various fields in cultural heritage. To understand the material properties of these historic surface coatings it is important to get insight in the technological background, i.e. the relationship between the material and the processing method. This study has specif- ically focused on the use of pumice stone and bone ash often mentioned in historical sources as driers for oil-based coating systems. For this purpose lute and Italian violins from the period between the 16th to the mid 18th century were examined. Both, the main organic composition of the varnish and the addition of mineral additives were considered. Based on the analytical data and the corresponding information from historical written sources, the siccativation of oil-based varnishes with pumice stone and bone ash was simulated experimentally. The results of these reconstructions confirm that the technological know-how behind these varnishes is far more complex than it may appear at first glance and that the organic and inorganic components must be regarded as a balanced technological system where each of the various components has a specific function. In this context, these inorganic additives effectively induced accel- erated drying, improved the mechanical film properties of young films and showed a stabilizing effect on the long-term degradation during aging.
Abstract Infrared spectroscopy (FTIR) is a standard technique for the characterisation of organic... more Abstract Infrared spectroscopy (FTIR) is a standard technique for the characterisation of organic materials in conservation science. This analytical technique is particularly interesting to analyse historical varnishes from cultural artefacts, as only minute samples are required. Some limitations apply, however, when analysing such chemically complex multi-component materials with interfering absorption bands. A previously introduced sample pre-treatment method using gaseous sulfur tetrafluoride SF 4 has shown to widen the application fields of the IR-technique by improving its specificity. One of these new fields is its successful application to the characterisation of complex aged natural varnish and lacquer systems. The fluorination treatment leads to characteristic band shifts of four individual saturated and unsaturated acid groups attached at varying positions of the terpene backbone. This allows the separation of otherwise overlapping carbonyl bands of different ketones and ester groups. Based on this technique, inert and unique functional groups can be used as material specific markers to identify drying oil, shellac and different terpene resins in varnishes and lacquers. The proposed markers proved to be stable for several hundred years. These findings are particularly interesting, as it is now possible to trace such markers even in very old varnishes dating back to the 16th century – with a likewise simple technique.
The inclusion of minerals in Italian varnishes from the 16th to mid-18th centuries has long been ... more The inclusion of minerals in Italian varnishes from the 16th to mid-18th centuries has long been a source of speculation. Analysis of micro-samples from multiple locations on 30 reference instruments from the 16th to the mid-18th century as well as a comprehensive study of written sources have revealed a centuries-old tradition of using pumice stone and calcined bones as additives for oil varnishes. These new findings represent a paradigm shift in our understanding of historical varnishes and open up exciting new perspectives.
JEAN-PHILIPPE ECHARD and BALTHAZAR SOULIER reveal the results of their seven-year research into S... more JEAN-PHILIPPE ECHARD and BALTHAZAR SOULIER reveal the results of their seven-year research into Stradivari's varnish, using five of the master's instruments from Paris's Musée de la Musique
The historical varnish technology is of interest to various fields in cultural heritage. To under... more The historical varnish technology is of interest to various fields in cultural heritage. To understand the material properties of these historic surface coatings it is important to get insight in the technological background, i.e. the relationship between the material and the processing method. This study has specifically focused on the use of pumice stone and bone ash often mentioned in historical sources as driers for oil-based coating systems. For this purpose lute and Italian violins from the period between the 16 th to the mid 18 th century were examined. Both, the main organic composition of the varnish and the addition of mineral additives were considered. Based on the analytical data and the corresponding information from historical written sources, the siccativation of oil-based varnishes with pumice stone and bone ash was simulated experimentally. The results of these reconstructions confirm that the technological know-how behind these varnishes is far more complex than it may appear at first glance and that the organic and inorganic components must be regarded as a balanced technological system where each of the various components has a specific function. In this context, these inorganic additives effectively induced accelerated drying, improved the mechanical film properties of young films and showed a stabilizing effect on the long-term degradation during aging.
Infrared spectroscopy (FTIR) is a standard technique for the characterisation of organic material... more Infrared spectroscopy (FTIR) is a standard technique for the characterisation of organic materials in conservation science. This analytical technique is particularly interesting to analyse historical varnishes from cultural artefacts, as only minute samples are required. Some limitations apply, however, when analysing such chemically complex multi-component materials with interfering absorption bands. A previously introduced sample pre-treatment method using gaseous sulfur tetrafluoride SF4 has shown to widen the application fields of the IR-technique by improving its specificity. One of these new fields is its successful application to the characterisation of complex aged natural varnish and lacquer systems. The fluorination treatment leads to characteristic band shifts of four individual saturated and unsaturated acid groups attached at varying positions of the terpene backbone. This allows the separation of otherwise overlapping carbonyl bands of different ketones and ester groups. Based on this technique, inert and unique functional groups can be used as material specific markers to identify drying oil, shellac and different terpene resins in varnishes and lacquers. The proposed markers proved to be stable for several hundred years. These findings are particularly interesting, as it is now possible to trace such markers even in very old varnishes dating back to the 16th century – with a likewise simple technique.
The study of varnishes from musical instruments presents the difficulty of analysing very thin la... more The study of varnishes from musical instruments presents the difficulty of analysing very thin layers of heterogeneous materials on samples most of which are generally brittle and difficult to prepare. Such study is crucial to the understanding of historical musical instrument varnishing practices since written sources before 1800 are very rare and not precise. Fourier-transform infrared (FTIR) spectroscopy and imaging methods were applied to identify the major chemical components within the build-up of the varnish layers on a cello made by one of the most prominent French violin-makers of the eighteenth century (Jacques Boquay, ca. 1680–1730). Two types of FTIR imaging methods were used: scanning with a synchrotron-based microscope and full-field imaging using a 2D imager with a conventional source. An interpretation of the results obtained from these studies on the Boquay cello is that the maker first applied a proteinaceous layer, probably gelatine-based animal glue. He later applied a second layer based on a mixture of a drying oil and diterpenic resin from Pinaceae sp. From an historical perspective, the results complement previous studies by describing a second technique used for musical instrument finishes at the beginning of the eighteenth century in Europe. Figure FTIR spectromicroscopy study of a cello made by the luthier Jacques Boquay (Paris, ca. 1680-1729) shows that the maker first applied a proteinaceous layer, probably gelatine-based animal glue.
The historical varnish technology is of interest to various fields in cultural heritage. To under... more The historical varnish technology is of interest to various fields in cultural heritage. To understand the material properties of these historic surface coatings it is important to get insight in the technological background, i.e. the relationship between the material and the processing method. This study has specifically focused on the use of pumice stone and bone ash often mentioned in historical sources as driers for oil-based coating systems. For this purpose lute and Italian violins from the period between the 16 th to the mid 18 th century were examined. Both, the main organic composition of the varnish and the addition of mineral additives were considered. Based on the analytical data and the corresponding information from historical written sources, the siccativation of oil-based varnishes with pumice stone and bone ash was simulated experimentally. The results of these reconstructions confirm that the technological know-how behind these varnishes is far more complex than it may appear at first glance and that the organic and inorganic components must be regarded as a balanced technological system where each of the various components has a specific function. In this context, these inorganic additives effectively induced accelerated drying, improved the mechanical film properties of young films and showed a stabilizing effect on the long-term degradation during aging.
As early as the 17th century, lute and violin varnishes were (unlike varnishes on furniture and p... more As early as the 17th century, lute and violin varnishes were (unlike varnishes on furniture and paintings) regarded as an integral part of the original instruments, hence worthy of preservation. As a result, most old violins retain at least part of their original varnish. In recent years multidisciplinary scientific investigations on a large group of instruments have obtained significant new findings. A complementary array of analytical tools (such as light microscopy, infrared spectroscopy as well as gas and liquidchromatography) was applied to determine the structure and the chemical composition of the coats. The results provide new information on the materials that were used by the Masters, with a detailed characterization of the stratigraphy of the coatings. These natural scientific findings allow recognition of distinctive varnishes from diverse lutherie centre. A two-layer system has been generally established: a ground layer that fills the upper wood cells, and the actual varnish. Italian instruments, from 16th- century lutes to Stradivari violins, reveal an oil- resin-based ground. Instruments from north of the Alps generally show a glue-based ground. Mineral particles have been largely ruled out as main constituents of the ground layer. The actual varnish consists, before the mid-18th century, fundamentally of mixtures of drying oil and resins of the pine family. From a chemical perspective, the main differences among historical instrument varnishes (except the ground layer) reside in the colouring system. While Italian Renaissance lute makers and early luthiers from the north of the Alps coloured their red varnishes with soluble colourants or highly heated resins, Cremonese and Venetians luthiers of the 17th and 18th centuries used very fine crimson lake pigments mixed with inorganic red pigments. The possibilities and limits of the scientific characterization of varnishes for the identification of historical stringed instruments will be discussed.
The majority of historical violins have been in continuous use since the time of their creation. ... more The majority of historical violins have been in continuous use since the time of their creation. As a consequence, they have repeatedly been modified over time. Stringed instruments that have been put aside and unaltered for a long time are extremely rare. The intention of rendering historical collection instruments playable inevitably implies certain interventions such as setting up a sound post, bridge and strings, readjusting tuning pegs or re- gluing loose parts. A thorough understanding of the impact of such interventions on the material integrity is essential for the discussion of whether to play a historical stringed instrument. The aim of this paper is to present criteria for the evaluation of the invasiveness of restoration interventions to playing order from a material technological point of view. The discussion is based on recent treatments of two Italian violins from the 18th century: one from the workshop of Antonio Stradivari dated 1708 (Ex-Davidoff), belonging to the collection of the Musée de la musique in Paris, the other from the workshop of Giovanni Battista Gabbrielli, dated 1769 and belonging to a private collection. While the Stradivari violin reveals many previous modifications, the Gabbrielli instrument does not show any signs of restoration. The contrasting states of preservation are the basis for a comparative study of the invasiveness of restoration measures. The ability to assess the purity of the original materials and detecting potential contamination is crucial for material analytical studies. The discussion further emphasises how the ongoing development of scientific investigation methods must be taken into account when assessing the information contained in the materiality of musical instruments.
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Analysis of micro-samples from multiple locations on 30 reference instruments from the 16th to the mid-18th century as well as a comprehensive study of written sources have revealed a centuries-old tradition of using pumice stone and calcined bones as additives for oil varnishes.
These new findings represent a paradigm shift in our understanding of historical varnishes and open up exciting new perspectives.
Analysis of micro-samples from multiple locations on 30 reference instruments from the 16th to the mid-18th century as well as a comprehensive study of written sources have revealed a centuries-old tradition of using pumice stone and calcined bones as additives for oil varnishes.
These new findings represent a paradigm shift in our understanding of historical varnishes and open up exciting new perspectives.
In recent years multidisciplinary scientific investigations on a large group of instruments have obtained significant new findings. A complementary array of analytical tools (such as light microscopy, infrared spectroscopy as well as gas and liquidchromatography) was applied to determine the structure and the chemical composition of the coats. The results provide new information on the materials that were used by the Masters, with a detailed characterization of the stratigraphy of the coatings. These natural scientific findings allow recognition of distinctive varnishes from diverse lutherie centre.
A two-layer system has been generally established: a ground layer that fills the upper wood cells, and the actual varnish. Italian instruments, from 16th- century lutes to Stradivari violins, reveal an oil- resin-based ground. Instruments from north of the Alps generally show a glue-based ground. Mineral particles have been largely ruled out as main constituents of the ground layer. The actual varnish consists, before the mid-18th century, fundamentally of mixtures of drying oil and resins of the pine family. From a chemical perspective, the main differences among historical instrument varnishes (except the ground layer) reside in the colouring system. While Italian Renaissance lute makers and early luthiers from the north of the Alps coloured their red varnishes with soluble colourants or highly heated resins, Cremonese and Venetians luthiers of the 17th and 18th centuries used very fine crimson lake pigments mixed with inorganic red pigments.
The possibilities and limits of the scientific characterization of varnishes for the identification of historical stringed instruments will be discussed.
The intention of rendering historical collection instruments playable inevitably implies certain interventions such as setting up a sound post, bridge and strings, readjusting tuning pegs or re- gluing loose parts. A thorough understanding of the impact of such interventions on the material integrity is essential for the discussion of whether to play a historical stringed instrument. The aim of this paper is to present criteria for the evaluation of the invasiveness of restoration interventions to playing order from a material technological point of view.
The discussion is based on recent treatments of two Italian violins from the 18th century: one from the workshop of Antonio Stradivari dated 1708 (Ex-Davidoff), belonging to the collection of the Musée de la musique in Paris, the other from the workshop of Giovanni Battista Gabbrielli, dated 1769 and belonging to a private collection. While the Stradivari violin reveals many previous modifications, the Gabbrielli instrument does not show any signs of restoration.
The contrasting states of preservation are the basis for a comparative study of the invasiveness of restoration measures. The ability to assess the purity of the original materials and detecting potential contamination is crucial for material analytical studies. The discussion further emphasises how the ongoing development of
scientific investigation methods must be taken into account when assessing the information contained in the materiality of musical instruments.