Optical Coherence Tomography (OCT) is an imaging technique originally developed for high-resoluti... more Optical Coherence Tomography (OCT) is an imaging technique originally developed for high-resolution 3D imaging of the human eye. In 2004, Targowski et al. and Liang et al. first reported its application to paintings, demonstrating that it was possible to produce cross-section images noninvasively with this technique. In 2005 Liang et al. explored further applications such as imaging of underdrawing at a resolution and contrast greater than that achievable with infrared reflectography Since then the authors have been conducting a project to investigate systematically the potential of O C T as a new tool in the non-invasive examination of paintings and to design an O C T optimised for use in museums. This paper discusses recent developments in this work and presents examples of the use of O CT on paintings undergoing conservation treatment in the National Gallery, London.
Close Document Image Close Document Printer Image Print This Document! Conservation Information N... more Close Document Image Close Document Printer Image Print This Document! Conservation Information Network (BCIN). Author: Saunders, David; Kirby, Jo Editor: Roy, Ashok; Smith, Perry Title Article/Chapter: "Wavelength-dependent ...
Discusses the advantages and disadvantages of glazing paintings for display and travel. Reflectiv... more Discusses the advantages and disadvantages of glazing paintings for display and travel. Reflectivity, strength, weight, colour, and ultraviolet absorption of plain, etched, and metal oxide-coated glass were considered. These values are summarised for glass types currently available. The preferred but most expensive choice is a low-iron laminated glass with a low reflective coating, followed by ordinary glass laminate with a low reflective coating. Plastics with low reflective and scratch-resistant coatings would be even better, but are not yet available in large sheets.
A range of traditional organic pigments was ground in gum arabic and applied to conservation grad... more A range of traditional organic pigments was ground in gum arabic and applied to conservation grade paper. Different sets were exposed to filtered gallery lighting at 80 and 200 lux and to multiple exposure to photographic flash units with and without ultraviolet filters, until each set had received the same exposure. Blue wool standards 1-3 were also exposed. Colour measurements showed that the modest degree of fading produced was the same for each lighting situation, i.e., the reciprocity rule for exposure to light held in these circumstances. This indicates that modern flash units are not powerful enough to initiate two-photon degradation processes, as had been suggested in the past. In view of this, the National Gallery recommendations for photographic lighting now favour flash over continuous lighting because the total exposure during a photographic session is lower with flash photography.
Journal of the Chemical Society, Dalton Transactions, 1986
X-Ray investigation of the product of the reaction of trans-[Ru(CO)2Cl2(PMe2Ph)2] with Hg(CCPh)2s... more X-Ray investigation of the product of the reaction of trans-[Ru(CO)2Cl2(PMe2Ph)2] with Hg(CCPh)2shows it to be [Ru(CO)2{C(CCPh)C(Ph)HgCl}Cl(PMe2Ph)2]. The proposed mechanism involves formation on the ruthenium of 1,4-diphenylbuta-1,3-diyne, and cis addition of an Ru–HgCl bond across one of the triple bonds of the diyne. The mass spectrum of the complex indicates that this addition is reversed on heating, with release of the diyne. The related complex [Ru(CO)2{C(CCCMe3)C(CMe3)HgCl}Cl(PMe2Ph)2], prepared in the same way, decomposes slowly in solution even at room temperature, with release of Me3CCC-CCCMe3 and deposition of mercury.
Journal of the Chemical Society, Dalton Transactions, 1985
In the presence of CHCl3, CCl4, or Etl, diary1 complexes [Ru(CO)2(C6H4Y-4)(C6H4Y′-4)L2](Y = Y′= M... more In the presence of CHCl3, CCl4, or Etl, diary1 complexes [Ru(CO)2(C6H4Y-4)(C6H4Y′-4)L2](Y = Y′= Me, L = PMe2Ph or AsMe2Ph; Y = Y′= Cl, L = PMe2Ph; Y = Me, Y′= Cl, L = PMe2Ph) are converted in solution into products [R[graphic omitted])C6H4Y}XL2], where X = Cl or I. The structure of [R[graphic omitted])C6H4Me}Cl(PMe2Ph)2], complex (3a), has been determined by X-ray crystallography. The proposed mechanism involves a two-step combination of aryl and carbonyl ligands to give [Ru(CO){OC(C6H4Y-4)(C6H4Y′–4)}L2], followed by insertion of the metal into a C–H bond in one of the arene rings and reaction of the resulting hydrido-complex with the halogen-containing compound. Probably as a result of the stereochemistry of the insertion step, the product [R[graphic omitted])C6H4Y}XL2] is initially obtained as an isomer with mutually cis L ligands; this then rearranges to the isolated product with trans L ligands. The iodide ligand in the complex [R[graphic omitted])C6H4Me}I(PMe2Ph)2] can be displaced by Me3CNC, and the complete organic ligand in complex (3a) is transferred from ruthenium to mercury on treatment with HgCl2.
Journal of the Chemical Society, Dalton Transactions, 1984
Methyl complexes [Ru(CO)2MeR(PMe2Ph)2][(1a), R = Ph; (1b), R = COMe; (1c), R = Me] react with Me3... more Methyl complexes [Ru(CO)2MeR(PMe2Ph)2][(1a), R = Ph; (1b), R = COMe; (1c), R = Me] react with Me3CNC to form acetyl complexes [Ru(CO)(CNCMe3)(COMe)R(PMe2Ph)2], (2a)–(2c). The reaction rate is independent of isonitrile concentration, and the rate-determining step is believed to involve combination of methyl and carbonyl ligands. The reactions of complexes (1b) and (1c) are similar both in rate and in activation parameters, but for (1a)ΔH‡ is appreciably lower and S‡ more negative: this may be due to increasing Ru–Ph π bonding in the approach to the transition state. Complex (2c) reacts with more Me3CNC to form [Ru(CO)(CNCMe3)(COMe){C(NCMe3)Me}-(PMe2Ph)2], (3c). Here the rate-determining step appears to involve combination of methyl and isonitrile ligands; this is much slower than combination of methyl and carbonyl ligands owing to a more negative ΔS‡. In the absence of added Me3CNC, complex (2c) slowly disproportionates into (1c) and (3c).
Journal of the Chemical Society, Dalton Transactions, 1984
Reactions of diaryl complexes [Ru(CO)2RR′(PMe2Ph)2] with Me3CNC yield the acyl complexes [Ru(CO)(... more Reactions of diaryl complexes [Ru(CO)2RR′(PMe2Ph)2] with Me3CNC yield the acyl complexes [Ru(CO)(CNCMe3)(COR)R′(PMe2Ph)2]. Rate-determining combination of aryl and carbonyl ligands is followed by rapid attack by isonitrile trans to the acyl ligand. In symmetrical diaryl complexes, rates are increased by electron-releasing substituents in the para position of the aryl ring. A methyl substituent in the meta position has a rather large accelerating effect, presumably for steric reasons. In unsymmetrical diaryl complexes, the aryl ligand bearing the more electron-releasing substituent becomes incorporated in the acyl ligand. Variations in the aryl ligand not directly involved in the reaction have little effect on rate, and solvent effects are relatively small. The fairly large negative entropies of activation are attributed to the formation in the transition state of a three-membered metal–carbonyl–aryl ring, in which the aryl ring has presumably lost its freedom of rotation.
Journal of the Chemical Society, Dalton Transactions, 1983
Whereas HgR2(R = methyl or aryl) converts trans-[Ru(CO)2Cl2(PMe2Ph)2] exclusively into [Ru(CO)2R(... more Whereas HgR2(R = methyl or aryl) converts trans-[Ru(CO)2Cl2(PMe2Ph)2] exclusively into [Ru(CO)2R(Cl)(PMe2Ph)2] and does not react with cis-[Ru(CO)2Cl2(PMe2Ph)2], LiR reacts with either isomer to yield [Ru(CO)2R2(PMe2Ph)2] and also catalyses conversion of the trans isomer into the cis. The initial attack by R– is believed to be on a carbonyl ligand. Treatment of [Ru(CO)2R(Cl)(PMe2Ph)2] with LiR′ yields mixed complexes [Ru(CO)2R(R′)(PMe2Ph)2]. In all cases the two organic ligands are mutually cis. The dimethyl complex undergoes reversible carbonylation to form mono- and di-acetyl complexes, and [Ru(CO)2Me(Ph)(PMe2Ph)2] also forms an acetyl complex, but aryl ligands are unaffected by treatment with CO.
ABSTRACT The European Commission-funded MARC project ended in April 1996, with the publication of... more ABSTRACT The European Commission-funded MARC project ended in April 1996, with the publication of Flemish Baroque Painting, Masterpieces of the Alte Pinakothek, Muenchen (Hirmer 1996). To the best of our knowledge, this is the world's first all- digital colorimetric art catalogue. This paper will briefly introduce the MARC camera and the MARC printing technology, and then present a critical evaluation of the final book. The application of MARC results since the end of the project will be covered, and related EC imaging projects surveyed.
Although digital multispectral imaging-particularly ultraviolet-induced fluorescence imaging-is a... more Although digital multispectral imaging-particularly ultraviolet-induced fluorescence imaging-is a very common examination tool, its interpretation remains fraught with difficulties. Interpretation is strongly dependent on the capture methodology, requires an understanding of the ...
Fiber Optic Sensor Technology and Applications IV, 2005
Scientific examinations of paintings are routinely carried out in major galleries and museums to ... more Scientific examinations of paintings are routinely carried out in major galleries and museums to assist in conservation treatment and as part of technical or art historical examinations. Care is taken to examine the paintings non-destructively as far as possible. However, in order to study the paint and varnish layers, it is still currently necessary to take tiny samples of a
Optical Coherence Tomography (OCT) is an imaging technique originally developed for high-resoluti... more Optical Coherence Tomography (OCT) is an imaging technique originally developed for high-resolution 3D imaging of the human eye. In 2004, Targowski et al. and Liang et al. first reported its application to paintings, demonstrating that it was possible to produce cross-section images noninvasively with this technique. In 2005 Liang et al. explored further applications such as imaging of underdrawing at a resolution and contrast greater than that achievable with infrared reflectography Since then the authors have been conducting a project to investigate systematically the potential of O C T as a new tool in the non-invasive examination of paintings and to design an O C T optimised for use in museums. This paper discusses recent developments in this work and presents examples of the use of O CT on paintings undergoing conservation treatment in the National Gallery, London.
Close Document Image Close Document Printer Image Print This Document! Conservation Information N... more Close Document Image Close Document Printer Image Print This Document! Conservation Information Network (BCIN). Author: Saunders, David; Kirby, Jo Editor: Roy, Ashok; Smith, Perry Title Article/Chapter: "Wavelength-dependent ...
Discusses the advantages and disadvantages of glazing paintings for display and travel. Reflectiv... more Discusses the advantages and disadvantages of glazing paintings for display and travel. Reflectivity, strength, weight, colour, and ultraviolet absorption of plain, etched, and metal oxide-coated glass were considered. These values are summarised for glass types currently available. The preferred but most expensive choice is a low-iron laminated glass with a low reflective coating, followed by ordinary glass laminate with a low reflective coating. Plastics with low reflective and scratch-resistant coatings would be even better, but are not yet available in large sheets.
A range of traditional organic pigments was ground in gum arabic and applied to conservation grad... more A range of traditional organic pigments was ground in gum arabic and applied to conservation grade paper. Different sets were exposed to filtered gallery lighting at 80 and 200 lux and to multiple exposure to photographic flash units with and without ultraviolet filters, until each set had received the same exposure. Blue wool standards 1-3 were also exposed. Colour measurements showed that the modest degree of fading produced was the same for each lighting situation, i.e., the reciprocity rule for exposure to light held in these circumstances. This indicates that modern flash units are not powerful enough to initiate two-photon degradation processes, as had been suggested in the past. In view of this, the National Gallery recommendations for photographic lighting now favour flash over continuous lighting because the total exposure during a photographic session is lower with flash photography.
Journal of the Chemical Society, Dalton Transactions, 1986
X-Ray investigation of the product of the reaction of trans-[Ru(CO)2Cl2(PMe2Ph)2] with Hg(CCPh)2s... more X-Ray investigation of the product of the reaction of trans-[Ru(CO)2Cl2(PMe2Ph)2] with Hg(CCPh)2shows it to be [Ru(CO)2{C(CCPh)C(Ph)HgCl}Cl(PMe2Ph)2]. The proposed mechanism involves formation on the ruthenium of 1,4-diphenylbuta-1,3-diyne, and cis addition of an Ru–HgCl bond across one of the triple bonds of the diyne. The mass spectrum of the complex indicates that this addition is reversed on heating, with release of the diyne. The related complex [Ru(CO)2{C(CCCMe3)C(CMe3)HgCl}Cl(PMe2Ph)2], prepared in the same way, decomposes slowly in solution even at room temperature, with release of Me3CCC-CCCMe3 and deposition of mercury.
Journal of the Chemical Society, Dalton Transactions, 1985
In the presence of CHCl3, CCl4, or Etl, diary1 complexes [Ru(CO)2(C6H4Y-4)(C6H4Y′-4)L2](Y = Y′= M... more In the presence of CHCl3, CCl4, or Etl, diary1 complexes [Ru(CO)2(C6H4Y-4)(C6H4Y′-4)L2](Y = Y′= Me, L = PMe2Ph or AsMe2Ph; Y = Y′= Cl, L = PMe2Ph; Y = Me, Y′= Cl, L = PMe2Ph) are converted in solution into products [R[graphic omitted])C6H4Y}XL2], where X = Cl or I. The structure of [R[graphic omitted])C6H4Me}Cl(PMe2Ph)2], complex (3a), has been determined by X-ray crystallography. The proposed mechanism involves a two-step combination of aryl and carbonyl ligands to give [Ru(CO){OC(C6H4Y-4)(C6H4Y′–4)}L2], followed by insertion of the metal into a C–H bond in one of the arene rings and reaction of the resulting hydrido-complex with the halogen-containing compound. Probably as a result of the stereochemistry of the insertion step, the product [R[graphic omitted])C6H4Y}XL2] is initially obtained as an isomer with mutually cis L ligands; this then rearranges to the isolated product with trans L ligands. The iodide ligand in the complex [R[graphic omitted])C6H4Me}I(PMe2Ph)2] can be displaced by Me3CNC, and the complete organic ligand in complex (3a) is transferred from ruthenium to mercury on treatment with HgCl2.
Journal of the Chemical Society, Dalton Transactions, 1984
Methyl complexes [Ru(CO)2MeR(PMe2Ph)2][(1a), R = Ph; (1b), R = COMe; (1c), R = Me] react with Me3... more Methyl complexes [Ru(CO)2MeR(PMe2Ph)2][(1a), R = Ph; (1b), R = COMe; (1c), R = Me] react with Me3CNC to form acetyl complexes [Ru(CO)(CNCMe3)(COMe)R(PMe2Ph)2], (2a)–(2c). The reaction rate is independent of isonitrile concentration, and the rate-determining step is believed to involve combination of methyl and carbonyl ligands. The reactions of complexes (1b) and (1c) are similar both in rate and in activation parameters, but for (1a)ΔH‡ is appreciably lower and S‡ more negative: this may be due to increasing Ru–Ph π bonding in the approach to the transition state. Complex (2c) reacts with more Me3CNC to form [Ru(CO)(CNCMe3)(COMe){C(NCMe3)Me}-(PMe2Ph)2], (3c). Here the rate-determining step appears to involve combination of methyl and isonitrile ligands; this is much slower than combination of methyl and carbonyl ligands owing to a more negative ΔS‡. In the absence of added Me3CNC, complex (2c) slowly disproportionates into (1c) and (3c).
Journal of the Chemical Society, Dalton Transactions, 1984
Reactions of diaryl complexes [Ru(CO)2RR′(PMe2Ph)2] with Me3CNC yield the acyl complexes [Ru(CO)(... more Reactions of diaryl complexes [Ru(CO)2RR′(PMe2Ph)2] with Me3CNC yield the acyl complexes [Ru(CO)(CNCMe3)(COR)R′(PMe2Ph)2]. Rate-determining combination of aryl and carbonyl ligands is followed by rapid attack by isonitrile trans to the acyl ligand. In symmetrical diaryl complexes, rates are increased by electron-releasing substituents in the para position of the aryl ring. A methyl substituent in the meta position has a rather large accelerating effect, presumably for steric reasons. In unsymmetrical diaryl complexes, the aryl ligand bearing the more electron-releasing substituent becomes incorporated in the acyl ligand. Variations in the aryl ligand not directly involved in the reaction have little effect on rate, and solvent effects are relatively small. The fairly large negative entropies of activation are attributed to the formation in the transition state of a three-membered metal–carbonyl–aryl ring, in which the aryl ring has presumably lost its freedom of rotation.
Journal of the Chemical Society, Dalton Transactions, 1983
Whereas HgR2(R = methyl or aryl) converts trans-[Ru(CO)2Cl2(PMe2Ph)2] exclusively into [Ru(CO)2R(... more Whereas HgR2(R = methyl or aryl) converts trans-[Ru(CO)2Cl2(PMe2Ph)2] exclusively into [Ru(CO)2R(Cl)(PMe2Ph)2] and does not react with cis-[Ru(CO)2Cl2(PMe2Ph)2], LiR reacts with either isomer to yield [Ru(CO)2R2(PMe2Ph)2] and also catalyses conversion of the trans isomer into the cis. The initial attack by R– is believed to be on a carbonyl ligand. Treatment of [Ru(CO)2R(Cl)(PMe2Ph)2] with LiR′ yields mixed complexes [Ru(CO)2R(R′)(PMe2Ph)2]. In all cases the two organic ligands are mutually cis. The dimethyl complex undergoes reversible carbonylation to form mono- and di-acetyl complexes, and [Ru(CO)2Me(Ph)(PMe2Ph)2] also forms an acetyl complex, but aryl ligands are unaffected by treatment with CO.
ABSTRACT The European Commission-funded MARC project ended in April 1996, with the publication of... more ABSTRACT The European Commission-funded MARC project ended in April 1996, with the publication of Flemish Baroque Painting, Masterpieces of the Alte Pinakothek, Muenchen (Hirmer 1996). To the best of our knowledge, this is the world's first all- digital colorimetric art catalogue. This paper will briefly introduce the MARC camera and the MARC printing technology, and then present a critical evaluation of the final book. The application of MARC results since the end of the project will be covered, and related EC imaging projects surveyed.
Although digital multispectral imaging-particularly ultraviolet-induced fluorescence imaging-is a... more Although digital multispectral imaging-particularly ultraviolet-induced fluorescence imaging-is a very common examination tool, its interpretation remains fraught with difficulties. Interpretation is strongly dependent on the capture methodology, requires an understanding of the ...
Fiber Optic Sensor Technology and Applications IV, 2005
Scientific examinations of paintings are routinely carried out in major galleries and museums to ... more Scientific examinations of paintings are routinely carried out in major galleries and museums to assist in conservation treatment and as part of technical or art historical examinations. Care is taken to examine the paintings non-destructively as far as possible. However, in order to study the paint and varnish layers, it is still currently necessary to take tiny samples of a
IIC's 2014 Hong Kong Congress, the 25th biennial congress, was titled An Unbroken History: Conser... more IIC's 2014 Hong Kong Congress, the 25th biennial congress, was titled An Unbroken History: Conserving East Asian Works of Art and Heritage. Five days of intensive cultural and knowledge exchange encompassed a range of material types, advances in preventive conservation, and new applications of materials. A number of recurring topics emerged at the Congress, including the study, examination, conservation, and analysis of East Asian lacquer. This special issue of Studies in Conservation draws together these contributions, allowing many of those who presented papers or posters in Hong Kong to cover their subjects in greater detail than was possible within the constraints of the Congress preprints, published in both Chinese and English. Several authors have taken this opportunity to update and expand the scope of their papers, and this special issue also benefits from the inclusion of key additional contributions from leading researchers in the field.
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