This study deals with the post-treatment evaluation of the elastic crossbar system already design... more This study deals with the post-treatment evaluation of the elastic crossbar system already designed and installed on the recently restored panel painting Deposition from the Cross by an anonymous artist from Abruzzo (sixteenth century). After the restoration, the panel and the crossbars were subjected to mechanical tests to identify their elastic characteristics. Then the panel, equipped with the elastic crossbar system, was subjected for about two months to controlled environmental cycles made up of approximately constant humidity periods. During the two months, the forces exerted by the springs and the deformations of both panel and crossbars were continuously monitored. A mathematical model, calibrated on the specific parameters derived from the analysis of the panel, provided the deformation that the panel would have shown without the crossbars; comparing the model output with the measured data provided a restraining effect (RE) of approximately 7% (RE could range between zero – no restraint – and 100% – total restraint). Future developments of this project will define appropriate procedures to design an elastic crossbar system for a given panel, once the expert judgement of restorers has identified the most desirable RE to be achieved.
Wooden Panel Paintings (WPP) are among the most significant historical and artistic artifacts fro... more Wooden Panel Paintings (WPP) are among the most significant historical and artistic artifacts from the Middle Ages and Renaissance and pose a challenge to conservators and scientists in both their comprehension and conservation. From a structural point of view, they can be considered as multi-layered objects, consisting of a wooden support and several pictorial layers. The wooden support, hygroscopic in nature, constantly seeks equilibrium with the humidity of the environment, and consequently deforms. Based on a series of hygroscopic tests carried out on six original WPPs, the present work aims to model their deformation tendencies induced by moisture changes and to characterise them by means of an inverse identification process. The sensitivity analysis of this study provided valuable insights into the complexity of the phenomenon of WPP deformation: even small variations in input variables (board anatomy, stiffness and emissivity of pictorial layers) led to significant changes in...
Wooden panel paintings are among the most important historical and artistic artworks from the Mid... more Wooden panel paintings are among the most important historical and artistic artworks from the Middle Ages and the Renaissance period. Currently, they represent a challenge for conservators and scientists who face complex issues related to their conservation. Panel paintings can be considered multilayer objects, that for brevity can be considered to consist of a wooden support and various paint layers. The wooden support is known to be hygroscopic and is continuously seeking hygroscopic equilibrium with the humidity of the environment, thus it tends to deform. Based on various hygroscopic tests carried out on 6 real panel paintings chosen by expert restorers to represent different periods and construction techniques, this paper describes the deformation tendencies of the selected panel paintings. Among possible variables, three most important variables were identified: (a) tree ring orientation of the wooden support, (b) stiffness and (c) emissivity of the paint layers. The internal ...
A non destructive diagnostic method for cultural heritage assets based on mi- crowave re∞ectometr... more A non destructive diagnostic method for cultural heritage assets based on mi- crowave re∞ectometry has been studied and developed. This new method is implemented with a ridged antenna operating in the range 1.5{3GHz for the detection of re∞ected wave amplitude and phase variation due to the dielectric properties of the materials under investigation. Particular interest has been devoted to wood structures attacked by fungi and insects and to mural paintings with delaminations due to subsurface humidity. A simplifled model of the antenna coupled to the material has been implemented in terms of a cascade of transmission lines in order to investigate the response of the system in presence of dielectric discontinuities. A series of laboratory models have been developed to assess the capability of the method to display in real time images of a calculated parameter which includes both amplitude and phase variation respect to a reference response taken from a homogeneous portion of the inve...
IOP Conference Series: Materials Science and Engineering, 2020
A collaboration aiming to improve knowledge and procedures for conservation of Panel Paintings ha... more A collaboration aiming to improve knowledge and procedures for conservation of Panel Paintings has been in force since several years between OPD (Opificio delle Pietre Dure, Florence) and the Research Group on Wood Technology of DAGRI (University of Florence). In such framework a research is here presented, which for the first time has led to dimensioning rationally (i.e. by means of objective criteria based on Conservation, on Engineering and on Wood Science principles) the stiffness of the crossbeams of an original Panel Painting. Crossbeams typically have a double function: a) to control the deformation of the panel painting when it undergoes climate changes and b) to stiffen the panel painting for handling purposes. If too stiff or too yielding, crossbeams might damage the wooden support or the paint layers; until today the choice of their stiffness was entrusted to the expert but subjective judgment of the Restorers alone, who therefore have been calling for a confrontation wit...
IOP Conference Series: Materials Science and Engineering, 2020
When wooden supports of panel paintings have been severely altered or damaged and the original cr... more When wooden supports of panel paintings have been severely altered or damaged and the original crossbeams are missing, new crossbeams or other types of auxiliary supports can be connected to the panel’s back-face in order to achieve desired effects including panel strengthening and control of deformations. In order to make such connection, the Restorers of Opificio delle Pietre Dure use small wooden blocks, each glued on the back face of the panel, and holding freely the head of a screw connected (often by means of springs) to the auxiliary support; the English term ‘buttons’ has been proposed for such blocks. This research examines in depth how the shape (conical or cylindrical) and dimensions (diameter in the 20-30 mm range, and thickness in the 3-6 mm range) of the buttons, all made from oak wood, influence their stiffness and load-carrying capacity. Each button was glued onto a dummy beech board by means of epoxy structural resin; a 3 mm diameter steel screw was inserted in each...
Wooden support: constituent materials, state of conservation, treatment of restoration and evalua... more Wooden support: constituent materials, state of conservation, treatment of restoration and evaluation of their effectiveness
The request by the Mugello region for the painting's restoration was initiated to confirm its... more The request by the Mugello region for the painting's restoration was initiated to confirm its supposed14th century Florentine provenance and to remedy its poor visibility caused by heavy repainting. The technical difficulty of the restoration and the analysis of its artistic technique required several years of work by a team of specialists from the OPD and the Superintendency of the region. The removal of numerous layers of overpaint to reveal the original painting allowed for its renewed reading and attribution to the hand of Lippo di Bienvieni. Work included archival research; spectrometry for the chemical identification of materials; research into the materials and techniques of manufacture; the state of conservation of the constitutive materials and past restoration campaigns; x-radiography; and cross-sectional analysis. The treatment involved disinfestation and structural stabilization of the wooden support; surface cleaning; consolidation; mechanical overpaint removal; app...
This study deals with the post-treatment evaluation of the elastic crossbar system already design... more This study deals with the post-treatment evaluation of the elastic crossbar system already designed and installed on the recently restored panel painting Deposition from the Cross by an anonymous artist from Abruzzo (sixteenth century). After the restoration, the panel and the crossbars were subjected to mechanical tests to identify their elastic characteristics. Then the panel, equipped with the elastic crossbar system, was subjected for about two months to controlled environmental cycles made up of approximately constant humidity periods. During the two months, the forces exerted by the springs and the deformations of both panel and crossbars were continuously monitored. A mathematical model, calibrated on the specific parameters derived from the analysis of the panel, provided the deformation that the panel would have shown without the crossbars; comparing the model output with the measured data provided a restraining effect (RE) of approximately 7% (RE could range between zero – no restraint – and 100% – total restraint). Future developments of this project will define appropriate procedures to design an elastic crossbar system for a given panel, once the expert judgement of restorers has identified the most desirable RE to be achieved.
La Scheda di restauro descrive l'intervento eseguito presso il Settore di restauro Materiali cart... more La Scheda di restauro descrive l'intervento eseguito presso il Settore di restauro Materiali cartacei e membranacei dell'OPD sul foglio miniato con la Crocifissione del Beato Angelico, che costituisce uno dei capisaldi del corpus di miniature assegnate dalla critica al pittore. La miniatura appartiene al Museo dell’abbazia di Vallombrosa.
This study deals with the post-treatment evaluation of the elastic crossbar system already design... more This study deals with the post-treatment evaluation of the elastic crossbar system already designed and installed on the recently restored panel painting Deposition from the Cross by an anonymous artist from Abruzzo (sixteenth century). After the restoration, the panel and the crossbars were subjected to mechanical tests to identify their elastic characteristics. Then the panel, equipped with the elastic crossbar system, was subjected for about two months to controlled environmental cycles made up of approximately constant humidity periods. During the two months, the forces exerted by the springs and the deformations of both panel and crossbars were continuously monitored. A mathematical model, calibrated on the specific parameters derived from the analysis of the panel, provided the deformation that the panel would have shown without the crossbars; comparing the model output with the measured data provided a restraining effect (RE) of approximately 7% (RE could range between zero – no restraint – and 100% – total restraint). Future developments of this project will define appropriate procedures to design an elastic crossbar system for a given panel, once the expert judgement of restorers has identified the most desirable RE to be achieved.
Wooden Panel Paintings (WPP) are among the most significant historical and artistic artifacts fro... more Wooden Panel Paintings (WPP) are among the most significant historical and artistic artifacts from the Middle Ages and Renaissance and pose a challenge to conservators and scientists in both their comprehension and conservation. From a structural point of view, they can be considered as multi-layered objects, consisting of a wooden support and several pictorial layers. The wooden support, hygroscopic in nature, constantly seeks equilibrium with the humidity of the environment, and consequently deforms. Based on a series of hygroscopic tests carried out on six original WPPs, the present work aims to model their deformation tendencies induced by moisture changes and to characterise them by means of an inverse identification process. The sensitivity analysis of this study provided valuable insights into the complexity of the phenomenon of WPP deformation: even small variations in input variables (board anatomy, stiffness and emissivity of pictorial layers) led to significant changes in...
Wooden panel paintings are among the most important historical and artistic artworks from the Mid... more Wooden panel paintings are among the most important historical and artistic artworks from the Middle Ages and the Renaissance period. Currently, they represent a challenge for conservators and scientists who face complex issues related to their conservation. Panel paintings can be considered multilayer objects, that for brevity can be considered to consist of a wooden support and various paint layers. The wooden support is known to be hygroscopic and is continuously seeking hygroscopic equilibrium with the humidity of the environment, thus it tends to deform. Based on various hygroscopic tests carried out on 6 real panel paintings chosen by expert restorers to represent different periods and construction techniques, this paper describes the deformation tendencies of the selected panel paintings. Among possible variables, three most important variables were identified: (a) tree ring orientation of the wooden support, (b) stiffness and (c) emissivity of the paint layers. The internal ...
A non destructive diagnostic method for cultural heritage assets based on mi- crowave re∞ectometr... more A non destructive diagnostic method for cultural heritage assets based on mi- crowave re∞ectometry has been studied and developed. This new method is implemented with a ridged antenna operating in the range 1.5{3GHz for the detection of re∞ected wave amplitude and phase variation due to the dielectric properties of the materials under investigation. Particular interest has been devoted to wood structures attacked by fungi and insects and to mural paintings with delaminations due to subsurface humidity. A simplifled model of the antenna coupled to the material has been implemented in terms of a cascade of transmission lines in order to investigate the response of the system in presence of dielectric discontinuities. A series of laboratory models have been developed to assess the capability of the method to display in real time images of a calculated parameter which includes both amplitude and phase variation respect to a reference response taken from a homogeneous portion of the inve...
IOP Conference Series: Materials Science and Engineering, 2020
A collaboration aiming to improve knowledge and procedures for conservation of Panel Paintings ha... more A collaboration aiming to improve knowledge and procedures for conservation of Panel Paintings has been in force since several years between OPD (Opificio delle Pietre Dure, Florence) and the Research Group on Wood Technology of DAGRI (University of Florence). In such framework a research is here presented, which for the first time has led to dimensioning rationally (i.e. by means of objective criteria based on Conservation, on Engineering and on Wood Science principles) the stiffness of the crossbeams of an original Panel Painting. Crossbeams typically have a double function: a) to control the deformation of the panel painting when it undergoes climate changes and b) to stiffen the panel painting for handling purposes. If too stiff or too yielding, crossbeams might damage the wooden support or the paint layers; until today the choice of their stiffness was entrusted to the expert but subjective judgment of the Restorers alone, who therefore have been calling for a confrontation wit...
IOP Conference Series: Materials Science and Engineering, 2020
When wooden supports of panel paintings have been severely altered or damaged and the original cr... more When wooden supports of panel paintings have been severely altered or damaged and the original crossbeams are missing, new crossbeams or other types of auxiliary supports can be connected to the panel’s back-face in order to achieve desired effects including panel strengthening and control of deformations. In order to make such connection, the Restorers of Opificio delle Pietre Dure use small wooden blocks, each glued on the back face of the panel, and holding freely the head of a screw connected (often by means of springs) to the auxiliary support; the English term ‘buttons’ has been proposed for such blocks. This research examines in depth how the shape (conical or cylindrical) and dimensions (diameter in the 20-30 mm range, and thickness in the 3-6 mm range) of the buttons, all made from oak wood, influence their stiffness and load-carrying capacity. Each button was glued onto a dummy beech board by means of epoxy structural resin; a 3 mm diameter steel screw was inserted in each...
Wooden support: constituent materials, state of conservation, treatment of restoration and evalua... more Wooden support: constituent materials, state of conservation, treatment of restoration and evaluation of their effectiveness
The request by the Mugello region for the painting's restoration was initiated to confirm its... more The request by the Mugello region for the painting's restoration was initiated to confirm its supposed14th century Florentine provenance and to remedy its poor visibility caused by heavy repainting. The technical difficulty of the restoration and the analysis of its artistic technique required several years of work by a team of specialists from the OPD and the Superintendency of the region. The removal of numerous layers of overpaint to reveal the original painting allowed for its renewed reading and attribution to the hand of Lippo di Bienvieni. Work included archival research; spectrometry for the chemical identification of materials; research into the materials and techniques of manufacture; the state of conservation of the constitutive materials and past restoration campaigns; x-radiography; and cross-sectional analysis. The treatment involved disinfestation and structural stabilization of the wooden support; surface cleaning; consolidation; mechanical overpaint removal; app...
This study deals with the post-treatment evaluation of the elastic crossbar system already design... more This study deals with the post-treatment evaluation of the elastic crossbar system already designed and installed on the recently restored panel painting Deposition from the Cross by an anonymous artist from Abruzzo (sixteenth century). After the restoration, the panel and the crossbars were subjected to mechanical tests to identify their elastic characteristics. Then the panel, equipped with the elastic crossbar system, was subjected for about two months to controlled environmental cycles made up of approximately constant humidity periods. During the two months, the forces exerted by the springs and the deformations of both panel and crossbars were continuously monitored. A mathematical model, calibrated on the specific parameters derived from the analysis of the panel, provided the deformation that the panel would have shown without the crossbars; comparing the model output with the measured data provided a restraining effect (RE) of approximately 7% (RE could range between zero – no restraint – and 100% – total restraint). Future developments of this project will define appropriate procedures to design an elastic crossbar system for a given panel, once the expert judgement of restorers has identified the most desirable RE to be achieved.
La Scheda di restauro descrive l'intervento eseguito presso il Settore di restauro Materiali cart... more La Scheda di restauro descrive l'intervento eseguito presso il Settore di restauro Materiali cartacei e membranacei dell'OPD sul foglio miniato con la Crocifissione del Beato Angelico, che costituisce uno dei capisaldi del corpus di miniature assegnate dalla critica al pittore. La miniatura appartiene al Museo dell’abbazia di Vallombrosa.
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dei capisaldi del corpus di miniature assegnate dalla
critica al pittore. La miniatura appartiene al Museo dell’abbazia
di Vallombrosa.
dei capisaldi del corpus di miniature assegnate dalla
critica al pittore. La miniatura appartiene al Museo dell’abbazia
di Vallombrosa.