References of "Defeyt, Catherine"
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See detailInsight on Van Dongen’s La Violoiste by hyperspectral imaging and MA-XRF
Herens, Elodie ULg; Strivay, David ULg; Walter, Philippe et al

Conference (2016, July 06)

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See detail“Color is a kind of holy substance for me”: analytical study of the Sam Francis’ palette from the 1940’s to the 1990’s
Defeyt, Catherine ULg; Mazurek, Joy; Zebala, Aneta et al

Poster (2016, March)

The Sam Francis’s colors, literally described as vivid, saturated, pure, vibrant intense and rich, largely contribute to the unique character of his work. This idiosyncrasy explains the interest in ... [more ▼]

The Sam Francis’s colors, literally described as vivid, saturated, pure, vibrant intense and rich, largely contribute to the unique character of his work. This idiosyncrasy explains the interest in conducting an extended study on the Francis’ painting materials through analytical techniques. On the other hand, many Francis’ paintings display colored surfaces that exhibit bronzing, fluorescent or opalescent effects. As a consequence, retouching paint losses from Sam Francis works may become a challenging task for the involved conservators, the degree of the color matching required in the imitative technique being particularly difficult to attain, in the presence of such surfaces. Furthermore, the attained degree of the color match has to be conserved in all conditions of illumination and observation. The use of pigments chemically similar to the original ones is often necessary for matching highly chromatic pigments. Though, many modern synthetic organic pigments (SOPs) possess high color strength. That is why the characterization of the Francis palette would provide helpful information to the conservators, which have to deal with this type of issue. The upcoming Getty publication Sam Francis: The Artist’s Materials, planned for 2016, offered the opportunity for in-depth analyses of hundreds paint samples. Almost three hundreds of paint fragments supplied by the Sam Francis Foundation have been investigated at the GCI laboratory, by using three complementary analytical techniques, Py-GC-MS, Raman and FTIR spectroscopies. The Raman spectroscopy is one of the most efficient techniques for identifying SOPs in paint systems, while the Py-GC-MS and FTIR methods provide essential information concerning the binding media. The analyzed paint fragments were sampled from twenty-nine canvases and works on paper, made between 1946 and 1992. Although, primary established in Southern California, Sam Francis spent numerous long journeys in different places around the world, including Paris, Bern, Mexico City, New York and Tokyo. However, the material study has outlined the uninterrupted use of` certain classes of SOPs in specific colors. For example, copper phthalocyanine (CuPc) pigments were systematically detected in the blue and green samples, while azo pigments have been identified in most of the yellow areas sampled from post 1940s works. Regardless of the support and the paint technique, the Francis’ blues primary contain Ultramarine and/or CuPc blue pigments. And, it has been shown that the bronzing blue surfaces noticed for some of the investigated artworks correspond to PB15-based paint films. The present study has also underlined the recurrent use of perinone orange and dioxazine violet in fluorescent orange and purple area. Despite the early introduction of SOPs, on the Francis’ palette, the works dating from the 1940’s remained mainly composed of traditional inorganic pigments, for instance lead white and red, chrome yellow, viridian and iron oxides. Interestingly, various binding media, i.e. Shellac gum, modified and unmodified oils, PVA, alkyd resins and acrylic copolymers have been identified. Actually, the investigated samples have pointed out the frequent combination of more than three types of binders on a same painting. Through the identification of the various SOPs used by Francis over fifty years, this research provide helpful information for selecting the most appropriate retouching pigments. [less ▲]

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See detailDevelopment of a translation stage for in situ non-invasive analysis and high resolution imaging
Strivay, David ULg; Clar, Mathieu ULg; Rakkaa, Saïd ULg et al

Poster (2016, March)

Non-invasive imaging techniques and analytical instrumentation for cultural heritage object studies have undergone a tremendous development over the last years. Many new miniature and/or handheld systems ... [more ▼]

Non-invasive imaging techniques and analytical instrumentation for cultural heritage object studies have undergone a tremendous development over the last years. Many new miniature and/or handheld systems have been developed and optimized. Nonetheless, these instruments are usually used with a tripod or a manual position system. This is very time consuming when performing point analysis or 2D scanning of a surface. The Centre Européen d’Archéométrie (CEA) has build a translation system made of pluggable rails of 1 m long with a maximum length and height of 3 m. Three motors embedded in the system allow the platform to be moved along these axis, toward and backward from the sample. The rails hold a displacement system, providing a continuous movement. Any position can be reached with a reproducibility of 0.1 mm. The displacements are controlled by an Ethernet connection through a laptop computer running a multiplatform homemade software written in JAVA. This software allows a complete control over the positioning using a simple, unique, and concise interface. Automatic scanning can be performed over a large surface of 3 meters on 3 meters. The Ethernet wires provide also the power for the different motors and, if necessary the detection head. The platform has been originally designed for a XRF detection head (with its full power alimentation) but now can accommodate many different systems like IR reflectography, digital camera, hyperspectral camera, Raman probes, etc. The positioning system can be modified to combine the acquisition software of the imaging or analytical techniques and the positioning software. [less ▲]

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See detailRecent technical developments of non-invasive cultural heritage analysis at the University of Liège
Strivay, David ULg; Chene, Grégoire ULg; Calvo Del Castillo, Helena ULg et al

Conference (2015, December 07)

The University of Liège has more than twenty years of experience in the use of ion beam analysis techniques for cultural heritage research. We will present here some of the recent developments. First, we ... [more ▼]

The University of Liège has more than twenty years of experience in the use of ion beam analysis techniques for cultural heritage research. We will present here some of the recent developments. First, we have developed a high energy extracted beamline up to 20 MeV on our cyclotron with a good energy resolution of a few keV. These last years Ion Beam Analysis users show an interest in High Energy Alpha beam. These beams can be used for on-site analysis by means of radioactive sources e.g. for space application but they also offer a powerful combination of properties for the analysis of thick layers (about 10 to 20 µm). This kind of layers are often met in cultural heritage applications but can be also present on new materials. Contrary to this kind of materials where the principal information needed is the in-depth profiles as the sample are of known composition, for cultural heritage materials the combination of elemental analysis and their in-depth distribution is essential as the nature of the material is a-priori not known. We will also present the development around our first extracted beamline. We have indeed improved the automatic scanning system for macro-PIXE. Some examples will be shown. Finally we will show other non-invasive analysis developments related to cultural heritage. [less ▲]

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See detailLocal Treatment for Monochrome Outdoor Painted Metal Sculptures: Assessing the suitability of conservation paints for retouching
van Basten, Nikki; Defeyt, Catherine ULg; Rivenc, Rachel

in Conservation of Sculpture Parks (2015, September)

When outdoor painted sculptures get chipped, scratched or abraded, conservators might consider local retouching treatments as an option that would protect the exposed metal substrate and restore the ... [more ▼]

When outdoor painted sculptures get chipped, scratched or abraded, conservators might consider local retouching treatments as an option that would protect the exposed metal substrate and restore the aesthetic integrity, thus postponing a very costly and invasive overall repainting. Unfortunately, matching colour gloss and texture on large monochrome surfaces is always challenging. This paper reports on research undertaken to investigate some of the materials and application techniques that could be used to improve the matching of local areas of inpainting as part of a broader maintenance strategy for painted works in sculpture parks, and discusses some of the advantages and disadvantages of working with both industrial products and conservation materials. Previous work by the lead author investigated the use of industrial paints to retouch monochrome painted metal sculptures, using Claes Oldenburg’s Trowel (1971) from the Kröller-Müller Museum as a case study. Several industrial products were tested and for Trowel it was found that using a paint of the same type as the original, manipulated to modify its gloss and colour, gave the best results. However, the original paint is not always available on the market because of product discontinuation or paint formulations changing over the years, and so research on alternative products was carried out at the Getty Conservation Institute. Instead of investigating industrial paint systems, a range of conservation paints and products that are usually employed in indoor applications were tested. Although these materials are unlikely to match the durability of industrial products in outdoor settings, they offer a number of advantages that might make them appropriate for temporary treatments, including a better workability for colour and gloss adjustments, a generally easier application procedure, better availability in small quantities, and a lower cost than their industrial counterparts. For the present study, a matte industrial paint that was recently developed as a coating for Alexander Calder sculptures was used as the target surface. Various conservation retouching paints were selected and used to retouch mock-ups prepared with these matte industrial paints, which were damaged with scratches and other mechanical means to reproduce typical damage to painted sculpture. The simulated scratches and losses were first primed and filled using materials that were selected in consultation with conservators and the paint industry. Since the composition of some of these products was unclear they were analysed and determined. The retouching was then carried out as a last step, applying the paint with an airbrush and using an ‘over-the-edge spray technique’. Some of the retouching paints were modified following the advice of the manufacturer to improve workability or durability. The colour retention of the various products is currently being tested with artificial aging in a weatherometer; the adhesion of the local treatment and the compatibility with the overall paint will be tested with the mock-ups placed outdoors for an extended period of time. Preliminary results show that the workability of some of the products tested is satisfying and that the retouching, when carried out properly, reintegrates both the paint coherence and the visual aspect of the artwork. [less ▲]

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See detailLocal Treatment for Monochrome Outdoor Painted Metal Sculptures: Assessing the suitability of conservation paints for retouching
van Basten, Nikki; Defeyt, Catherine ULg; Rivenc, Rachel

in Conservation of Sculpture Parks (2015, September)

When outdoor painted sculptures get chipped, scratched or abraded, conservators might consider local retouching treatments as an option that would protect the exposed metal substrate and restore the ... [more ▼]

When outdoor painted sculptures get chipped, scratched or abraded, conservators might consider local retouching treatments as an option that would protect the exposed metal substrate and restore the aesthetic integrity, thus postponing a very costly and invasive overall repainting. Unfortunately, matching colour gloss and texture on large monochrome surfaces is always challenging. This paper reports on research undertaken to investigate some of the materials and application techniques that could be used to improve the matching of local areas of inpainting as part of a broader maintenance strategy for painted works in sculpture parks, and discusses some of the advantages and disadvantages of working with both industrial products and conservation materials. Previous work by the lead author investigated the use of industrial paints to retouch monochrome painted metal sculptures, using Claes Oldenburg’s Trowel (1971) from the Kröller-Müller Museum as a case study. Several industrial products were tested and for Trowel it was found that using a paint of the same type as the original, manipulated to modify its gloss and colour, gave the best results. However, the original paint is not always available on the market because of product discontinuation or paint formulations changing over the years, and so research on alternative products was carried out at the Getty Conservation Institute. Instead of investigating industrial paint systems, a range of conservation paints and products that are usually employed in indoor applications were tested. Although these materials are unlikely to match the durability of industrial products in outdoor settings, they offer a number of advantages that might make them appropriate for temporary treatments, including a better workability for colour and gloss adjustments, a generally easier application procedure, better availability in small quantities, and a lower cost than their industrial counterparts. For the present study, a matte industrial paint that was recently developed as a coating for Alexander Calder sculptures was used as the target surface. Various conservation retouching paints were selected and used to retouch mock-ups prepared with these matte industrial paints, which were damaged with scratches and other mechanical means to reproduce typical damage to painted sculpture. The simulated scratches and losses were first primed and filled using materials that were selected in consultation with conservators and the paint industry. Since the composition of some of these products was unclear they were analysed and determined. The retouching was then carried out as a last step, applying the paint with an airbrush and using an ‘over-the-edge spray technique’. Some of the retouching paints were modified following the advice of the manufacturer to improve workability or durability. The colour retention of the various products is currently being tested with artificial aging in a weatherometer; the adhesion of the local treatment and the compatibility with the overall paint will be tested with the mock-ups placed outdoors for an extended period of time. Preliminary results show that the workability of some of the products tested is satisfying and that the retouching, when carried out properly, reintegrates both the paint coherence and the visual aspect of the artwork. [less ▲]

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See detailLocal Treatment for Monochrome Outdoor Painted Metal Sculptures: Assessing the suitability of conservation paints for retouching
van Basten, Nikki; Defeyt, Catherine ULg; Rivenc, Rachel

in Conservation of Sculpture Parks (2015, September)

When outdoor painted sculptures get chipped, scratched or abraded, conservators might consider local retouching treatments as an option that would protect the exposed metal substrate and restore the ... [more ▼]

When outdoor painted sculptures get chipped, scratched or abraded, conservators might consider local retouching treatments as an option that would protect the exposed metal substrate and restore the aesthetic integrity, thus postponing a very costly and invasive overall repainting. Unfortunately, matching colour gloss and texture on large monochrome surfaces is always challenging. This paper reports on research undertaken to investigate some of the materials and application techniques that could be used to improve the matching of local areas of inpainting as part of a broader maintenance strategy for painted works in sculpture parks, and discusses some of the advantages and disadvantages of working with both industrial products and conservation materials. Previous work by the lead author investigated the use of industrial paints to retouch monochrome painted metal sculptures, using Claes Oldenburg’s Trowel (1971) from the Kröller-Müller Museum as a case study. Several industrial products were tested and for Trowel it was found that using a paint of the same type as the original, manipulated to modify its gloss and colour, gave the best results. However, the original paint is not always available on the market because of product discontinuation or paint formulations changing over the years, and so research on alternative products was carried out at the Getty Conservation Institute. Instead of investigating industrial paint systems, a range of conservation paints and products that are usually employed in indoor applications were tested. Although these materials are unlikely to match the durability of industrial products in outdoor settings, they offer a number of advantages that might make them appropriate for temporary treatments, including a better workability for colour and gloss adjustments, a generally easier application procedure, better availability in small quantities, and a lower cost than their industrial counterparts. For the present study, a matte industrial paint that was recently developed as a coating for Alexander Calder sculptures was used as the target surface. Various conservation retouching paints were selected and used to retouch mock-ups prepared with these matte industrial paints, which were damaged with scratches and other mechanical means to reproduce typical damage to painted sculpture. The simulated scratches and losses were first primed and filled using materials that were selected in consultation with conservators and the paint industry. Since the composition of some of these products was unclear they were analysed and determined. The retouching was then carried out as a last step, applying the paint with an airbrush and using an ‘over-the-edge spray technique’. Some of the retouching paints were modified following the advice of the manufacturer to improve workability or durability. The colour retention of the various products is currently being tested with artificial aging in a weatherometer; the adhesion of the local treatment and the compatibility with the overall paint will be tested with the mock-ups placed outdoors for an extended period of time. Preliminary results show that the workability of some of the products tested is satisfying and that the retouching, when carried out properly, reintegrates both the paint coherence and the visual aspect of the artwork. [less ▲]

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See detailLocal Treatment for Monochrome Outdoor Painted Metal Sculptures: Assessing the suitability of conservation paints for retouching
van Basten, Nikki; Defeyt, Catherine ULg; Rivenc, Rachel

in Conservation of Sculpture Parks (2015, September)

When outdoor painted sculptures get chipped, scratched or abraded, conservators might consider local retouching treatments as an option that would protect the exposed metal substrate and restore the ... [more ▼]

When outdoor painted sculptures get chipped, scratched or abraded, conservators might consider local retouching treatments as an option that would protect the exposed metal substrate and restore the aesthetic integrity, thus postponing a very costly and invasive overall repainting. Unfortunately, matching colour gloss and texture on large monochrome surfaces is always challenging. This paper reports on research undertaken to investigate some of the materials and application techniques that could be used to improve the matching of local areas of inpainting as part of a broader maintenance strategy for painted works in sculpture parks, and discusses some of the advantages and disadvantages of working with both industrial products and conservation materials. Previous work by the lead author investigated the use of industrial paints to retouch monochrome painted metal sculptures, using Claes Oldenburg’s Trowel (1971) from the Kröller-Müller Museum as a case study. Several industrial products were tested and for Trowel it was found that using a paint of the same type as the original, manipulated to modify its gloss and colour, gave the best results. However, the original paint is not always available on the market because of product discontinuation or paint formulations changing over the years, and so research on alternative products was carried out at the Getty Conservation Institute. Instead of investigating industrial paint systems, a range of conservation paints and products that are usually employed in indoor applications were tested. Although these materials are unlikely to match the durability of industrial products in outdoor settings, they offer a number of advantages that might make them appropriate for temporary treatments, including a better workability for colour and gloss adjustments, a generally easier application procedure, better availability in small quantities, and a lower cost than their industrial counterparts. For the present study, a matte industrial paint that was recently developed as a coating for Alexander Calder sculptures was used as the target surface. Various conservation retouching paints were selected and used to retouch mock-ups prepared with these matte industrial paints, which were damaged with scratches and other mechanical means to reproduce typical damage to painted sculpture. The simulated scratches and losses were first primed and filled using materials that were selected in consultation with conservators and the paint industry. Since the composition of some of these products was unclear they were analysed and determined. The retouching was then carried out as a last step, applying the paint with an airbrush and using an ‘over-the-edge spray technique’. Some of the retouching paints were modified following the advice of the manufacturer to improve workability or durability. The colour retention of the various products is currently being tested with artificial aging in a weatherometer; the adhesion of the local treatment and the compatibility with the overall paint will be tested with the mock-ups placed outdoors for an extended period of time. Preliminary results show that the workability of some of the products tested is satisfying and that the retouching, when carried out properly, reintegrates both the paint coherence and the visual aspect of the artwork. [less ▲]

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See detailTowards portable X-ray spectroscopic imaging of Palaeolithic cave art. Insights into used pigments and wall taphonomy at three Palaeolithic key cave sites
Gay, Marine; Muller, Katharina; Plassard, Frédéric et al

Poster (2014, May)

Palaeolithic cave art has taken a more and more important place in our cultural heritage. Its preservation is one of the major issues and involves necessarily a better understanding of the cave ... [more ▼]

Palaeolithic cave art has taken a more and more important place in our cultural heritage. Its preservation is one of the major issues and involves necessarily a better understanding of the cave environments and of their evolution over time. However, the on-site geo-physico- chemical study of archaeological record stays dif cult and the conservation of its integrity imposes restrictions. Taking bene t of recent analytical developments in the X-ray eld, new perspectives of acquiring statistically relevant data for archaeological interpretation directly in the eld are provided by the implementation of portable and non-invasive characterization methods. It allows the improvement of archaeological and physico-chemical knowledge about the pigments used, the evaluation of the state of wall decorated surfaces over time and a better assessment of the relationship between pigment and wall support. For these purposes, complementary self-built portable spectrometers (X-ray uorescence in one and two dimensional mode, X-ray diffraction) are combined to perform qualitative and quantitative characterization of the pigments and cave walls as well as for chemical imaging on a decimetre scale. By using this combination of portable instruments the feasibility of analysis under very dif cult conditions speci c to the cave environments (humidity, temperature, dif cult access to the caves and to the decorated panels) was shown. Special spectrum evaluation procedures have been developed to take into account the heterogeneity of the cave walls in order to gain reliable data for chemical characterisation. The ef ciency of the analytical procedure has been demonstrated for three major cave sites featuring Palaeolithic art: Font-de-Gaume and Rouf gnac cave in Dordogne (France) and La Garma in Cantabria (Spain). A large assortment of colours can be observed in these caves (red, black, yellow and purple), associated to different mineral phases (iron and/or manganese oxides, charcoal and mixtures). Their detailed characterization provides an improved comprehension of the pictorial techniques used. Furthermore, it allows a better comparison between representations in a same cave, giving more detailed insights into its pictorial homogeneity and the different execution phases of its gures. As an example, the results obtained at Rouf gnac cave showed that heterogeneous mixtures of manganese oxides have been employed to design the 65 Great Ceiling gures whereas a unique pigment mixture has been used for the drawing of the Ten Mammoths Frieze. Further information has been obtained on the taphonomic wall processes. The spectroscopic study of these cave art illustrate the strong potential of such combined in situ and non-invasive analyses to better characterize the prehistoric gures in their cave environment and in a wider perspective to better understand the symbolic practices of past societies, appreciate possible cultural changes and relationships within the Franco-Cantabrian region. [less ▲]

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See detailÉtude technique et matérielle des tableaux liégeois
Defeyt, Catherine ULg; Strivay, David ULg

in Duchesne, Jean-Patrick (Ed.) L'art dégénéré selon Hitler (2014)

Les études dans le domaine du patrimoine culturel peuvent généralement se ranger en deux catégories. La première catégorie concerne les analyses physico-chimiques qui visent à une meilleure compréhension ... [more ▼]

Les études dans le domaine du patrimoine culturel peuvent généralement se ranger en deux catégories. La première catégorie concerne les analyses physico-chimiques qui visent à une meilleure compréhension de l'œuvre via le gain d'information sur les matériaux utilisés et la technologie mise en œuvre. Ces données peuvent conduire à une datation de l'objet et à l'identification de son origine géographique et permettent de documenter l'évolution et l'histoire des techniques artistiques. La seconde classe de ces études archéométriques se focalise sur l'état de conservation de l'œuvre et sur l'origine de ses éventuelles altérations apparues au cours du temps. L'objectif est donc d'identifier ces mécanismes de dégradations car ces dernières peuvent significativement altérer la perception de l’œuvre et compliquer le travail de restauration, dont le but premier est de respecter l’intention initiale de l’artiste. Le but ultime de ce type d'études est d'optimiser les conditions de conservation des œuvres existantes et d'améliorer la durabilité des matériaux artistiques modernes qui seront utilisés dans le futur. Le Centre Européen d’Archéométrie de l’Université de Liège, fondé en 2003, s’est spécialisé dans l’étude du patrimoine culturel mobilier et immobilier. La bonne conduite des projets de recherches menés au Centre d’Archéométrie nécessite une étroite collaboration entre scientifiques et archéologues, conservateurs et historiens d’art. Le centre se veut un acteur dynamique dans la conservation du patrimoine culturel belge. Pour ce faire, il est nécessaire de dresser un premier bilan de l'état des objets conservés et de poser un diagnostic de leur état de conservation. Dans de nombreux cas, il est très difficile, voire inconcevable, de déplacer ou de prélever les objets du patrimoine culturel étudiés. C’est pourquoi les recherches sur les techniques d’analyse non invasives et mobiles connaissent un développement très important ces dernières années. Actuellement, l’utilisation combinée de plusieurs techniques mobiles, telles que la fluorescence X, la diffraction X, la spectroscopie Raman ou infrarouge à transformée Fourier reste très restreinte et peu exploitée lors des campagnes d’analyses in situ. La plateforme d’instruments portables du Centre Européen d’Archéométrie permet de documenter de manière complète et systématique les œuvres des collections et de poser un constat de l’état de conservation et d’altération de ces objets. Dans le cadre du partenariat de recherche entre le CEA et les musées de la Ville de Liège récemment mis en place et grâce à un financement du Fonds Jean-Jacques Comhaire (Fondation Roi Baudouin), nous avons étudié les tableaux de la vente de Lucerne de 1939. Ces œuvres majeures ne peuvent être déplacées et ont donc été étudiées par des méthodes mobiles. L'utilisation de la plate-forme expérimentale mise en place au Centre Européen d’Archéométrie a permis d'identifier les matériaux utilisés et de caractériser les techniques picturales des différents artistes. Nous montrons ici les résultats concernant les tableaux de Paul Gauguin, Pablo Picasso et James Ensor. [less ▲]

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See detailPB15 as 20th and 21st Artists’ Pigments: Conservation Concerns
Defeyt, Catherine ULg; Strivay, David ULg

in E‐Preservation Science (2014), 11

Copper phthalocyanine (CuPc) provides the most important blue and green pigments from the 21st century artists’ paints. This paper focuses on the blue pigments of CuPc, which are referenced in the Colour ... [more ▼]

Copper phthalocyanine (CuPc) provides the most important blue and green pigments from the 21st century artists’ paints. This paper focuses on the blue pigments of CuPc, which are referenced in the Colour Index as PB15. The employment of PB15 as artists’ pigments since the very beginning until now is summarized through archives of artists’ color makers and current color charts. Moreover, for the first time, a review of the cases of PB15 identifica- tion encountered in the field of cultural heritage is presented. For each case reported in this study, the analytical methods that allowed identifying the blue pigment are specified. The significance and the relevance of various destructive and non-destructive methods, for this topic in particular are also discussed. Finally, the implications of PB15 in common conservation prac- tices are outlined. [less ▲]

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See detailDistinction by micro-Raman spectroscopy and chemometrical analysis of copper phthalocyanine blue polymorphs in oil-based and acrylic samples
Defeyt, Catherine ULg; Van Pevenage, Jolien; Learner, Tom et al

in Van den berg, K.J.; Burnstock, A.; de Tagle, A. (Eds.) et al Issues in Contemporary Oil Paints (2014)

Copper phthalocyanine (CuPc) blue, commonly named phthalo blue is the most important synthetic organic blue pigment in the 20th and 21st century artists paints. Phthalo blue, which is adopted by artists ... [more ▼]

Copper phthalocyanine (CuPc) blue, commonly named phthalo blue is the most important synthetic organic blue pigment in the 20th and 21st century artists paints. Phthalo blue, which is adopted by artists since 1936, is a polymorphous pigment. Currently, the alpha, beta and epsilon CuPc polymorphs are used in artists paint formulations. The identification of the CuPc crystal form provides technical and chronological information relevant for studying artworks. Raman Spectroscopy (RS) is a very valuable technique for the detection of phthalo blue in paint layers. However, the spectral interpretation is not straightforward concerning the CuPc polymorph distinction. To overcome the problem we have previously developed a procedure combining RS and chemometrical analysis. The experimental results that we obtained have demonstrated its efficiency for predicting the CuPc crystal form in unknown paint samples. In the present work, this procedure was applied on oil-based and acrylic paints from Sam Francis’ studio and the Getty Conservation Institute (GCI) Reference Collection. [less ▲]

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See detailAnalytical study of “La Famille Soler” by Picasso: from the Blue Period to Cubism
Defeyt, Catherine ULg; Vekemans, Bart; Vandenabeele, Peter et al

Poster (2013, September 23)

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See detailCopper phthalocyanine blue pigments in conservation
Defeyt, Catherine ULg

Doctoral thesis (2013)

The phthalocyanine family, and more specifically the copper phthalocyanines (CuPcs) are the most important blue and green artists’ pigments from the end of the 20th century. This thesis focuses on the ... [more ▼]

The phthalocyanine family, and more specifically the copper phthalocyanines (CuPcs) are the most important blue and green artists’ pigments from the end of the 20th century. This thesis focuses on the CuPc blue pigments used in the artists’ paint formulations. CuPc blue extensive use as modern artists’ pigment and its implications in conservation science are pointed out. Their discovery, chemical composition, molecular structure and general properties are also reviewed. Additionally, the polymorphism and the influence of the crystal form on the final properties of the phthalo blue pigments are discussed. A methodology using non-destructive techniques and statistical analysis is then presented. This new procedure allows the identification of the CuPc crystal form in paint layers and is suitable for artwork analysis. Some CuPc polymorphs are prone to crystallization defects in presence of aromatic solvents, leading to a reduction of color strength and a shift in hue. Crystallization resistance of the CuPc polymorphs has then been assessed by means of crystallization tests performed on dry pigments and on paint films. Case studies are then presented. La famille Soler by Picasso has been studied by imaging and non-invasive analytical techniques. The successive underlying compositions have been revealed and the pigments used for the different compositions have been characterized. Then micro-samples taken from Delvaux’s paintings and Francis and Lichtenstein’s studio paints have been analyzed to characterize the blue pigments preferred by these artists. The crystal form of the phthalo blue pigments identified from four micro-samples taken from two Léger and Pechstein fake paintings have been investigated as well. Finally, the historic phthalo blue samples from the Getty Conservation Institute Reference Collection have been studied. [less ▲]

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See detailPB15’s discrimination in oil paintings by non-destructive methods
Defeyt, Catherine ULg; Vandenabeele, Peter; Van Pevenage, Jolien et al

Poster (2013, March 29)

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See detailPB15 polymorphic distinction in paint samples by combining micro- Raman spectroscopy and chemometrical analysis
Van Pevenage, Jolien; Defeyt, Catherine ULg; Moens, Luc et al

Poster (2013)

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See detailMicro-Raman spectroscopy and chemometrical analysis for the distinction of copper phthalocyanine polymorphs in paint layers
Defeyt, Catherine ULg; Van Pevenage, Jolien; Moens, Luc et al

in Spectrochimica Acta Part A : Molecular and Biomolecular Spectroscopy (2013), 115

In art analysis, copper phthalocyanine (CuPc) is often identified as an important pigment (PB15) in 20th century artworks. Raman spectroscopy is a very valuable technique for the detection of this pigment ... [more ▼]

In art analysis, copper phthalocyanine (CuPc) is often identified as an important pigment (PB15) in 20th century artworks. Raman spectroscopy is a very valuable technique for the detection of this pigment in paint systems. However, PB15 is used in different polymorphic forms and identification of the polymorph could retrieve information on the production process of the pigment at the moment. Raman spectroscopy, being a molecular spectroscopic method of analysis, is able to discriminate between poly- morphs of crystals. However, in the case of PB15, spectral interpretation is not straightforward, and Raman data treatment requires some improvements concerning the PB15 polymorphic discrimination in paints. Here, Raman spectroscopy is combined with chemometrical analysis in order to develop a procedure allowing us to identify the PB15 crystalline structure in painted layers and in artworks. The results obtained by Linear Discriminant Analysis (LDA), using intensity ratios as variables, demonstrate the ability of this procedure to predict the crystalline structure of a PB15 pigment in unknown paint samples. [less ▲]

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See detailAutomatic X-ray fluorescence scanning mobile system for 2D chemical analysis
Strivay, David ULg; Hocquet, François-Philippe; Dister, Hervé et al

Conference (2012, December)

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