Studies in Conservation

Published by Maney Publishing
Online ISSN: 0039-3630
Publications
Thangka hung in a monastery (photo S. Cotte).
Pigments used in thangkas
Article
Thangkas (Tibetan painted banners) are religious objects still in use in their original Himalayan context; they are also encountered in Western collections where they are considered as ethnographic objects or works of art. Conservation of thangkas goes far beyond technical considerations and encompasses issues such as treatment of sacred objects in another culture, trans-disciplinary conservation and ethics in the conservation of living cultural heritage. This article reviews the publications on thangkas focused either on techniques and materials or on conservation treatment options. Treatment approaches have varied since the 1970s when thangkas were first mentioned in the conservation literature. These are discussed in the context of the conservation of living heritage and its role in the presentation and perception of diverse cultural identities.
 
Article
In the UK, the National Trust's portfolio of properties is owned for the benefit of the nation. The benefit is the promotion of access to the properties, while preserving them for the future. Collections are one element of this portfolio, and they can excite the support needed to ensure our properties' future. However, resources are limited and the costs of access can be seen to increase the costs of conservation. How can we justify this, when choosing between treating collections and repairing buildings, gardens and landscape? This paper discusses the place of access in the Trust's strategy, how we prioritize through the Conservation Performance Indicator and the Collections Conservation Prioritisation process, and how access is factored into these processes. A Triple Bottom Line approach enables evaluation of both conservation and social benefits, such as access, as well as financial costs, so one activity generates several objectives with sustainable outcomes. This approach demonstrates how collections conservation is adapting to the changing cultural heritage environment.
 
Article
Chloride-contaminated archaeological iron is unstable and problematic to store and display within museum collections. Reducing its chloride ion content using aqueous desalination followed by storage in controlled relative humidity offers one treatment option. This study reports a quantitative assessment of chloride extraction by aqueous deoxygenated alkaline desalination solutions from 120 individual archaeological iron nails. The three treatment methods comprised alkaline sulphite solution (0.1 M NaOH/0.05 M Na2SO3) at room temperature and at 60°C and sodium hydroxide solution (0.1 M) deoxygenated using a nitrogen gas positive pressure system at room temperature. Chloride extraction was monitored using a specific ion meter. The nails were digested after treatment to measure their residual chloride content. A wide range of extraction patterns emerged, with the majority of individual treatments extracting 60‐99% of the chloride present. Residual chloride levels for 87% of the objects fell below 1000 ppm and 42% were below 200 ppm. Although no treatment extracted 100% of the chloride in the object, alkaline desalination produced very significant reductions in chloride content. The impact of this on future corrosion of the objects is discussed. This quantitative and statistically viable assessment of deoxygenated desalination treatments provides evidence to support their use in conservation practice, which will impact on procedures for the preservation and management of archaeological heritage.
 
Article
Accurate estimates of cumulative light exposure are an important prerequisite for the assessment and limitation of photochemical damage to museum objects on display The task is complicated because spotlights used to highlight particular features illuminate objects' surfaces unevenly and also because indirect light sources, for example diffuse sunlight within exhibition spaces, result in changing total illumination levels throughout the day and seasonally. This paper presents a methodology for determining the annual light exposure of 2-D objects by combining the results of continuous light readings adjacent to the object and one-off point measurements over its illuminated surface, a method that allows a more accurate estimate of total exposure than either monitoring method alone. Two pieces of information are required to calculate Cumulative exposure: first, the ratio of direct to indirect lighting, which is arrived at by quantifying the amount of visible light falling on the object relative to that received by its surroundings; and, second, the diurnal and seasonal variation in illuminance of indirect light sources, particularly diffuse daylight. Two paintings in different galleries exposed to different ratios of diffuse sunlight to direct artificial light – one low and the other high – were used to refine and test the method.
 
Article
Tate is undertaking a major research project to assess the effects of anoxic storage on paper-based works of art. The outcomes will include: the design of a safe, affordable anoxic framing system suitable for both storage and display, capable of being incorporated into historic frames; guidelines on materials which would be harmed by anoxia and information on their recognition and behaviour. Such framing would provide safer access to paper-based works of art. This paper reviews the following materials found in paper-based works of art that are susceptible to oxidation and which could therefore benefit from anoxia: traditional colorants; modern pigments; graphic media; printing, copying or photographic processes; and oil or alkyd media. Materials, predominantly colorants, which may be susceptible to reducing reactions that proceed in the absence of oxygen, are identified for later study into their behaviour and their non-destructive identification on paper-based works of art.
 
Article
This paper establishes that the two-dimensional Fourier transform, spectral-maximum-based extraction of thread density appears suited to automatic thread counting from scanned X-radiographs of paintings for a range of European painters from the seventeenth century to the early twentieth century. With regularly woven canvas, striping occurring in color-coded maps of local thread count can be used to identify rollmate candidates originally separated by as much as a few meters, maybe more. These results suggest that recently developed spectral-maximum-based thread counting algorithms are sufficiently sophisticated to support major efforts in archival thread counting as key forensic data in a variety of art historical investigations. Still, the canvas and priming used by some artists require a more refined approach to automated thread counting than a simple spectral-maximum-based scheme.
 
Article
A paint box and palette that belonged to the American painter James McNeill Whistler(1834-1903) are in the Library of Congress, Washington, DC. There are 37 tubes of paint in the box, including 6 in a separate cardboard box labeled Spectrum Colors. There are also painting and etching tools. The tubes were supplied by five British colormen except for the Spectrum Colors, which came from the American firm of Devoe & Raynolds Inc. Some of the tube labels are missing or illegible. The pigments were identified using polarized light microscopy, X-ray powder diffraction, high performance liquid chromatography, and Raman spectroscopy. Information from Devoe & Raynold's catalogs suggests that the Spectrum Colors were not available before 1909; toluidine red, found in one Spectrum Color, was first synthesized in1904. Thus, the Spectrum Colors must have been put in the paint box after Whistler's death. Of the other pigments in the box, three – graphite, emerald green and synthetic malachite – are not known to have been used by him, but it may be that they are yet to be identified. The paint box was given to the Library of Congress by Joseph and Elizabeth Pennell in 1917, 14 years after the artist's death, and it is not known whether the paint box was used during that time.
 
Article
The use of rubber as a component of the grounds of artists' canvases appeared simultaneously in Britain and France, and such primed canvases became commercially available from around 1835 to the beginning of the 1850s. India rubber (so called as it first came from the 'India' discovered by Columbus) or elastic gum was at the time a new material in the visual arts. More generally, this product found vogue in many fields of manufacturing. The addition of rubber to grounds applied to artists' canvas was an extension of the process of waterproofing utilitarian fabrics then common in Britain and France. Rubber-based grounds were first mentioned in the conservation literature in 1981 by Byrne. The present paper seeks to identify manufacturers and individuals involved in the development of rubber-based artists' grounds. The study is based on textual sources and the few material sources which remain: handwritten recipes, patents, press releases, catalogues, marks on fabrics, and rare paintings on manufactured French and British fabrics. The deterioration aspects of grounds containing rubber are illustrated.
 
Article
The restoration of the Cavaillé-Coll Romantic organ housed in La Merced Church of Burgos, Spain is described in this paper. The organ was affected by a fire that took place in the church. The effect of the fire on the pipes differed depending on their location within the instrument. A combination of analytical techniques (X-ray diffraction, scanning electron microscopy with energy-dispersive X-ray analysis, particle-induced X-ray emission, metallography, and specific density) allowed the accurate determination of the microstructures and compositions of the alloys used to make the different pipes of the organ, some of which had a high tin content and others which had a high lead content. The most damaged pipes were replaced by reconstructed pipes made out of metallic sheets of the same composition as the originals, to ensure a historically accurate sound.
 
View from beneath the statue showing the wooden box contruction of the core. Photograph by Louis Meluso, Photo Services Department, J. Paul Getty Museum.
Detail of fleur-de-lis estofado pattern on the rear of the vestments. Photograph by Louis Meluso, Photo Services Department, J. Paul Getty Museum.  
Detail of the proper right hand showing encarnaciones. Photograph by Louis Meluso, Photo Services Department, J. Paul Getty Museum.
Article
A seventeenth-century sculpture of St Gines de la Jara by Louisa Roldan was technically examined and compared with Francisco Pacheco's seventh-century treatise 'Arte de la Pintura'. The sculpture was found to follow closely but not exactly the recommended practice of polychrome sculpture manufacture. The individual artist's practice was revealed after analysis by cross-section, polarized light microscopy (PLM), scanning electron microscopy with energy dispersive X-ray analysis (SEM-EDS) and gas chromatography-mass spectrometry (GC-MS).
 
Article
One of the small sites that dot the upper Tigris River valley in Turkey, Hirbemerdon Tepe is unique for its dominant feature: a well-preserved monumental complex dating to the first half of the second millennium bce. In this context a series of ceremonial objects were excavated, including the fragments of six clay votive plaques decorated with painted, incised and applied anthropomorphic and geometric motifs. The discovery of the ancient and possibly deliberate breakage of the plaques provides important information about the life history of these objects and instigated a dialogue about how such evidence should be approached during conservation treatment. The argument is enhanced through reconstruction of their life histories, and also by drawing on recent advances in the field of fragmentation theory in archaeological research. Challenges encountered during the conservation treatment of the plaques are discussed followed by future plans for their exhibition in the Diyarbakir Archaeological Museum.
 
The conservator working under close supervision of a senior Mayali man. 
Article
TJURKULPA is a term describing the three essential forms of respect for indigenous Australians of the central desert. Similar terms elsewhere outline the necessary respect for the Land, the Culture and the People. When a conservator becomes involved in the Culture, in this case rock paintings in a cultural landscape, it is important not to isolate the Culture from the People, the Land, or from other forms of non-visual culture. This paper will illustrate, through a range of experiences from several indigenous groups, the differences in cultural values that lead to divergent views of visual culture. Having re-focused on the significant issues of indigenous culture, the paper will detail a substantial research and method development program that has led to the stabilization of a major painting site in Kakadu National Park, nominated to the World Heritage register for both its cultural and natural values. The paper is pivoted around several telling anecdotes that have shaped the personal view of the conservator. Anecdotes, rather than charts, best tell the story of a relationship between science and a spiritual world where the conservator has no place to be, other than to provide professional services that may help preserve the painted images.
 
Article
Among the highlights of the Islamic art collection at The Metropolitan Museum of Art is the earliest surviving reception room from Damascus (AH 1119 /AD 1707), known as the Nur al-Din Room. The wooden paneling and ceilings of this interior are embellished with gesso relief decoration, called 'ajami, which is gilded, tin-leafed, glazed and painted to create a complex interplay of reflective or matte and intensely colored surfaces. As in many such rooms, the current appearance no longer reflects the original aesthetic, largely due to later varnishes that have darkened. This paper presents the results of a thorough study of the Room's materials and manufacturing techniques. The investigation, combined with research into its history and the study of Ottoman interiors in their original settings, enables a more accurate reinstallation and presentation of the room in the newly renovated galleries for Islamic art.
 
Article
The Oddy test is an 'accelerated' corrosion test employed by museums to evaluate the suitability of materials proposed for use in display and storage cases, The standard Oddy test requires a 28-day test period, and the results are assessed by visual observation. This paper describes an improved test method, which could reduce the length of the test period by half The improved method uses metal films as substitutes for the traditional metal coupons posing as 'surrogate art object', The new test results are then evaluated by computer with digital image processing for more objective selection of less corrosive materials.
 
Article
The paper considers the contribution that the history of science can make to conservation science and technical art history. In particular, it uses scientific texts from the thirteenth and fourteenth centuries to interpret the significance of materials on the Westminster Retable, c.1260. This prestigious altarpiece was decorated with imitation gems, and the paper explores the intellectual context in which it was conceived and created.
 
Article
The cause of yellowing of oil-based paints has been investigated by analysing drying oils simultaneously by iodometry (to determine the degree of oxidation) and by colorimetry. It was found that yellowing of drying oils can be attributed to co-oxidation reactions of contaminants. Yellowing level is closely related to the extent of drying and appears to be unaffected by increase in temperature, the addition of driers, or linolenate content. Spanish La causa del amarilleamiento en la pinturas de tipo oleoso ha sido investigada por medio del análisis de los aceites secativos en combinación con iodometría (para determinar el grado de oxidación) y de colorimetría. Se determinó que el amarilleamiento de los aceites secativos puede atribuirse a las reacciones de co-oxidación de los contaminantes. El nivel de amarilleamiento está íntimamente relacionado con el nivel de secado y parece no estar afectado por el incremento de la temperature, la adición de secativos o el contenido de linolenato. German Die Ursache für das Vergilben von ölhaltigen Malschichten wurde durch Analyse der trocknenden Öl durch Iodometrie (zur Bestimmung des Oxidationsgrades) bei gleichzeitiger Farbmessung untersucht. Es konnte gezeigt werden, daß die Vergilbung trocknender Öle der Oxidation von Verunreinigungen zugeschrieben werden kann. Der Grad der Vergilbung ist dabei eng mit dem Ausmaß der Trocknung verbunden, scheint aber unabhängig von Temperaturerhöhung, der Anwesenheit von Trocknungsbeschleunigern und dem Gehalt an Linolat zu sein. French On a recherché la cause du jaunissement des peintures à l'huile en analysant des huiles siccatives simultanément par iodométrie (qui permet de déterminer le degré d'oxydation) et par colorimétrie. On a trouvé que le jaunissement des huiles siccatives peut être attribué à des réactions de co-oxydation de contaminants. Le niveau de jaunissement est étroitement lié au degré de séchage et ne semble pas être affecté par l'élévation de la température, l'addition de siccatifs ou le contenu en linoléates.
 
Detail from the wall paintings in the nave of Gundsømagle Church, after retouching. The scene depicts a fragment from the last judgement, including the gaping mouth of hell.  
Drawing of the scene depicted in Fig. 1, executed by an architect. It shows how difficult it can be to comprehend forms in deteriorated images.  
Drawing of the scene depicted in Fig. 1, executed by a conservator . The blue lines are reconstructions based on an educated guess.  
Article
This paper presents results from a pilot study researching values and opinions of the general public regarding medieval wall paintings in Danish churches. It also addresses restoration issues, focusing primarily on the retouching, reconstruction and overpainting of images. The data have been obtained from questionnaires returned by 179 subjects. These were not representative of the Danish population in general, with women outnumbering men (65.4% versus 34.6%) and with high church attendance (48% 'regularly', 25.7% 'frequently') as the differentiating characteristics. The major finding of this study was that in this group, it was important to understand the pictorial content (58.7% 'very important', 35.2% 'important') and the narrative substance (rated as the highest value by 60.9%). The significance of these preferences for professional considerations regarding image integration is discussed. It is concluded that survey studies of this type provide a useful tool in shaping the dialogue between conservators and the general public.
 
Article
The widespread occurrence of thecotrichite, Ca3(CH3COO)3 Cl(NO3)2·7H2O, in the museum environment is explained theoretically by construction and examination of its phase diagram. Thecotrichite formation was simulated in the laboratory to identify the key factors involved in its production. This efflorescence occurs on porous limestone or calcareous artefacts such as pottery, stored in wooden cabinets that generate acetic acid vapour. Salt production depends on the moisture content of the object and the concentration of acetic acid in its surroundings. Furthermore, for thecotrichite to form the artefact must contain soluble chloride and nitrate salts.
 
Article
Thesis (M.A.)--New York University, 1966. Includes bibliographical references.
 
Article
Desiccation has long been used to store chloride-contaminated archaeological iron but there are no precise guidelines on the degree of desiccation required to prevent corrosion occurring. Akaganéite (β-FeOOH), ferrous chloride tetrahydrate (FeCl2·4H2O) and ferrous chloride dihydrate (FeCl2·2H2O) have been recorded on archaeological iron. Iron corrodes in the presence of FeCl2·4H2O and β-FeOOH but not in the presence of FeCl2·2H2O. The rate of desiccation of FeCl2·4H2O at various levels of relative humidity (RH) was determined by experiment and found to be an exponential relationship. The point at which FeCl2·2H2O first becomes a stable hydrate was established. Rates of corrosion for iron mixed with FeCl2·4H2O and with β-FeOOH were examined for a range of RH. The hygroscopicity of β-FeOOH and the RH at which it ceases to cause iron to corrode were established. Corrosion of iron in contact with FeCl2·4H2O and β-FeOOH speeds up as RH rises and is appreciable at 25% RH and above. On the basis of these results, recommendations are made that 12% should be the maximum allowable RH for long-term storage of archaeological iron from chloride-bearing soils. Low RH requirements raise problems for long-term monitoring of storage microclimates.
 
A site in southeastern Utah with graffiti carved over rock paintings. Studies in Conservation 39 (1994) 161-168 161
The 'Holy Ghost and Attendants' pictograph panel from the Great Gallery site in Barrier Canyon. Note the two figures to the left of this panel which lack their lower portions due to exfoliation. The 42WN418-1 sample was recovered by Cox [15] from the talus slope in the foreground.
The two pictographs to the left of the 'Holy Ghost' panel. Note the smeared outline of the right figure.
Article
Direct radiocarbon dating of pictographs has recently become possible. The authors report here the deleterious effects on such dating of hydrocarbon contamination of a pictograph in southeastern Utah. In order to enhance contrast between a pictograph and its rock substrate, some photographers have wetted pictographs with kerosene or similar substances; such 'enhancement' renders radiocarbon dates useless. Some treatments proposed for rock art deterioration may cause similar problems. /// La datation directe au C14 des pictographes est récemment devenue possible. Toutefois les auteurs rapportent ici les effets nuisibles sur une telle datation de la contamination hydrocarbonée d'un pictographe de l'Utah du Sud-Est. Dans le but de renforcer le contraste entre les pictographes et le substrat de rocher, quelques photographes avaient mouillé les pictographes avec du kérosène et des substances semblables; un tel 'renforcement' rend impossible les datations au C14. Quelques traitements employés pour l'art rupestre peuvent poser des problèmes semblables. /// Die Datierung von prähistorischen Felsenzeichnungen mit Hilfe der Radiokarbonmethode ist erst seit kurzer Zeit möglich. Die Verfasser berichten von zerstörerischen Nebenerscheinungen dieser Datierungsmethode in Form von Hydrokarbonkontamination am Beispiel eines Bildwerkes in Südost-Utah in den USA. Fotografen haben diese Piktogramme zur Kontrastverbesserung zwischen Zeichnung und Felsenuntergrund mit Kerosin und ähnlichen Substanzen genäßt; solche Manipulationen machen die Radiokarbonmethode höchst fragwürdig. Die Autoren weisen darauf hin, daß auch einige konservatorische Behandlungsmethoden vergleichbare Probleme hervorrufen können.
 
Article
Although atmospheric pollution can be reduced or eliminated in many different ways, each way involves questions of economics, the time factor, availability of materials, priority over other urgent reforms, and individual and social psychology. To provide a basis for consideration of these questions, this book gives information not only about the measurement, distribution, and effects of atmospheric pollution, but also goes into detail about fuel, fuel-burning appliances, industrial processes, and domestic requirements. The first eight chapters deal with fuels, furnaces, and fires: (1) Origin of Fuel, (2) Natural Solid Fuels, (3) Mineral Oils and Gases, (4) Manufactured Fuels, (5) Industrial Boilers, (6) Power and Electricity, (7) Industrial Furnaces, and (8) Domestic Heat Services. The five following chapters are given to a study of the properties of atmospheric pollution: (9) Atmospheric Pollution, (10) Measurement of Atmospheric Pollution, (11) Distribution of Pollution, (12) Changes in Pollution, and (13) Effects of Pollution. Remedial measures are considered in Prevention of Atmospheric Pollution. The last chapter is an account of the law in England and in other countries insofar as it concerns atmospheric pollution. Written with a semi-technical approach, the book is for professional people--public health officers, architects, engineers, meteorologists, legislators, city councillors, boiler operators, and builders. (BL)
 
Adult Red-shafted Flicker (Colaptes auratus cafer) (photo: courtesy of Kenneth McEnaney).
Maidu/Miwok dancers wearing flicker feather headdress regalia at Pt Reyes Big Time Festival on 26 July 2008 (photo: Ellen Pearlstein).
Note darker color tail feathers with tips, in contrast to paler wing feathers (Phoebe Hearst Museum, 1/700), donated in 1901 by Mrs P. Hearst; collected at Little Pomo Lake, Round Valley, Mendocino County, California (photo: Ellen Pearlstein)
Article
Fading behavior of undyed feathers has not received much attention in conservation literature and as a result feathers are categorized with other natural materials as being fugitive to display lighting, based on anecdotal evidence. The authors investigated Red-shafted Flicker feathers, which have carotenoid-based colorant systems and significance in North American native regalia, to demonstrate how lighting guidelines could be informed by a multivariate approach that considers material sensitivity, properties of value, and use before entering a museum collection. Ornithological literature reviewed demonstrates that feathers are highly differentiated in their sources of coloration, which include chemistry, structure, diet, age and,gender, all resulting in varying responses to illumination. The authors explore the value placed on color by original fabricators, and how use and attitudes toward color contribute to the collections for which we assume stewardship. Red-shafted Flicker feathers were exposed to equivalent photometric doses in order to compare results from window-fading and microfading to Blue Wool Standards. Results indicate color changes more stable than Blue Wool 1 and 2, with ultraviolet radiation playing a significant role in fading. Microfading is beneficial for measuring color change because the variability within and between feathers is eliminated as the sample site remains unvaried.
 
Tool marks caused by flattening the surface and in relation to the motif.
Cross-section showing a yellow sinopia underneath a thin intonaco subsequently painted red.
Map of the eastern Mediterranean, showing the location of Gla, Greece.
Sitemap of Gla, indicating the location of plaster finds (after [12: p. 23, plan 7]).
Article
This paper presents the first evidence of lapis lazuli or lazurite that was detected unexpectedly using micro-Raman spectroscopy during research to identify an enigmatic purple hue on the thirteenth-century BC Greek Bronze Age wall paintings from Gla. The lapis lazuli material was found as part of a mixture including a red iron oxide and an as yet unidentified purple staining material. Existing purple mixtures of that period are also discussed. The identification of lapis lazuli at Gla may prove to be the earliest known use of this pigment in buon fresco, in both Eastern and Western painting traditions. Furthermore, this precedes the next known use of the material as a pigment by 1800 years. The existence of this blue pigment is also discussed within the context of the blue pigment palette of the Bronze Age Aegean and eastern Mediterranean Bronze Age (3300-1100 BC), to show its use in relation to other blue materials and to demonstrate the technology and knowledge mastered by the artists who used this lazurite.
 
Article
The new Centre for Conservation at the British Library (BL) opened in London in 2007. It comprises state-of-the-art book conservation studios and sound preservation facilities, inextricably intertwined with an ambitious training and public outreach programme, all housed together in a beautiful, purpose-built, multi-million pound building next to the new Eurostar station at St Pancras in London. It is the only such centre to focus on the conservation of books and the preservation of sound. The presentation of the conservation of the BL’s holdings of the world’s cultural heritage and the public programmes were integral to the fundamental ideas behind the building, designed in from the earliest stages of the project. The paper describes the thinking behind this development and assesses the public engagement with conservation a year after the new building opened. The public programmes include a permanent, free exhibition on conservation and decision making at the entrance to the new conservation centre, linked to the rotation of iconic collection items within the BL’s Treasures Gallery. There are free, behind-the-scenes tours of the conservation studios for the public as well as demonstrations, workshops and talks to widen public access to the activities and concepts behind caring for the British Library’s vast collections. These developments at the British Library are considered in the wider context of trends in presenting cultural heritage. The paper concludes with developments in how conservation is contributing to international engagement and cultural diplomacy. Version of Record
 
Article
Technical studies have been carried out on bronze fragments excavated from burials at the site of Tianma-Qucun, Shanxi, China. The studies show that secondary metallic copper is very common both in the bronze core and in external corrosion layers, displaced as fine particles within cuprite, filled cracks and surface bands. Destannification has also been found. This paper presents observations of redeposited copper and discusses possible mechanisms of formation.
 
Article
The ‘Centre de Recherches sur la Conservation des Documents graphiques’ (Centre for the Research into the Conservation of Graphic Documents) was established in 1963. It depends on five directions: Archives, Libraries, Museums, National Centre of Scientific Research and Natural History Museum. The present number of staff is 9. The field of its activities covers all the constituent parts of graphic documents: papyrus, parchment, paper, ink, illuminated manuscripts, etc. The research activities are twofold, viz. applied research which consists in preparing and perfecting techniques before they are used for restoration purposes; analytical research of which the principal objects are the analysis and identification of the different components of graphic documents. Close relations have been established with laboratories in foreign countries, thanks to the icom Committee for Conservation, the International Institute for Conservation (nc) and the International Centre for Conservation which has its seat in Rome.
 
Title page and first page of Table of Contents, MS 372, Beinecke Library, Yale University.
Gherardo Cibo, Castle on rock, drawing in verzino di aceto on paper, Gabinatto Stampe e Disegni, Uffizi Gallery.
Chapter on various colour mixtures in Ricordi di belli colori with colour proofs in the margin, Urb. Lat. 1280, Biblioteca Apostolica Vaticana.
The Duke's ledger, notes of January 1590 listing the artists working at the workshops; other months just list a single total payment to the botteghini, Ducato di Urbino, Classe III, filza 23, Archivio di Stato Firenze.
Article
The early seventeenth-century Italian Mariani-Cibo treatise is a technical manual on miniature painting, botanical illustration and landscape drawing, compiled by the miniaturist Valerio Mariani (1568–c.1625) and including texts from botanist/artist Gherardo Cibo (1512–1600). Research revealed that it was written for use in the artists' workshops at Duke Francesco Maria II della Rovere's Pesaro court, reflecting the artists' activities and their patron's preferences. These workshops, founded by the Duke in 1581, represent a businesslike operation, with manager, communal buying-in of materials, inter-disciplinary co-operation and artistic and technical exchanges. It was found that the treatise contains recipes and technical instructions influenced by the various artists and disciplines in the court workshops and surroundings, showing how research of the context in which it originated is invaluable for a correct interpretation of this unique document. The treatise contains a wealth of information on materials and techniques, making it an invaluable source of information for conservators.
 
Article
In this study, the following methods of treatment have been studied: bulking with PEG 4000 in water, methanol and t-butanol solvents; bulking with PEG 540 blend in water; bulking with rosin in acetone; freeze-drying from different concentrations of PEG 400 with various methods of pre-freezing; in situ polymerization with glycol methacrylate and with a melamine formaldehyde resin; water displacement with methylene chloride followed by rosin impregnation. They have all been carried out with five groups of waterlogged wood representative of different species and various states of degradation. Freezedrying, PEG 4000 impregnation in t-butanol and PEG 540 blend impregnation in water gave the most satisfactory results, based on appearance and shrinkage.
 
The relationship between value, conservation and representation, which can be cyclic or linear.  
Feilden's [8] degrees of intervention with possible repercussions for heritage value
Article
Physical and intellectual access to heritage is shaped by conservation through a longterm, cyclic and symbiotic relationship of representation and intervention (or lack of it). This informs future use and representation. Value (which may be assigned for different reasons) makes heritage. All heritage is valued for varied reasons. Some argue that heritage has inherent value; this is not covered in this paper. Some values are preferred over others in decisions on what to use or conserve. The process below describes a number of different recurring phases in this relationship, which differs with different kinds of heritage: 1. Various agents change heritage; 2. Change affects valued elements of heritage; 3. Valued elements affect how change is perceived; 4. What is perceived as damage affects decisions about conservation interventions; 5. Conservation affects which valued elements are most likely to be preserved; 6. Preserved elements influence how heritage is represented; 7. New forms of representation will affect future conservation decisions. Historically, how heritage has been represented has affected how an object is preserved. This affects later representation and use, making the relationship symbiotic.
 
Article
The last 40 years have seen major changes in the sources and concentrations of urban pollution (nitrogen dioxide, sulfur dioxide, hydrogen sulfide, and particulates). During this time, research has advanced our understanding of the impact of pollutants on objects in urban museums. As a consequence, pollutant control has become an important aspect of preventive conservation. There is also increased awareness of the need for pollution control strategies that are sustainable at an organizational and global level. This report, prepared by a chemist, a conservator, and two building scientists, reviews strategies for minimizing the impact of urban pollution on museum collections. The results of new research funded by the UK government identify current (1999) internal pollution levels in both naturally ventilated and air-conditioned museums with particle and gaseous filtration, in relation to external concentrations, ventilation strategies, and the characteristics of the internal fabric and finishes of these buildings.
 
Article
This study concerns a group of objects excavated in First World War trenches in France and Belgium and brought for conservation to the Institute of Archaeology, University College London. These objects were associated with unidentified human remains thought to be of soldiers killed in battles between 1914 and 1918. The contribution of the Institute to this project was to investigate the objects in relation to their context in an attempt to identify the human remains with which they were associated. The experience of working on sensitive material in a very particular context is discussed, and how this influenced the conservation context in which the decision-making process happened is described. It also addresses how some conservation boundaries were crossed, in order to contribute to a better understanding of life during the First World War, and discusses how material culture is valued differently in different contexts (and how this will influence conservation decisions). It concludes that neither object meaning nor conservation decisions can be viewed objectively and that conservation has to be viewed as a social process governed by economic, political, religious, social and cultural dynamics, rather than a primarily technical process.
 
Article
Degradation of oil painted copper surfaces involves chemical, physical and mechanical processes that are influenced by the prevailing environment. The oil paint/copper interface formed between the lower layers of paint and its copper support determines the stability of the system. Components within the painted copper system are identified and their interactions are discussed. Decay routes are described. Ingress of water and ions to the oil paint/copper boundary through paint film defects is shown to be essential for the electrochemical reactions at the metal surface that lead to adhesion loss. Destabilisation begins with bond failure and blistering, which provides ideal conditions for the initiation of delamination. The study reveals that further work on the structure and properties of copper carboxylates of individual and mixed linseed oil fatty acids, together with models of their reaction, would further understanding in this field.
 
Article
Technical and chronological aspects of overglaze enamel production at historic porcelain factories in central Europe are discussed based on studies of over 180 objects at various laboratories. Results of analyses on representative objects, carried out primarily with X-ray fluorescence spectroscopy, are presented. Examples of eighteenth- and nineteenth-century decoration by Meissen, Du Paquier, and Hausmaler painters are described in detail. The findings highlight established glaze formulation practices and enhance understanding of the dating of objects based on the detection of zinc in yellow, blue, and green glazes. This study is the first to provide extensive scientific evidence on the composition of nineteenth-century overglaze enamel colors. In particular, the research highlights the frequent co-occurrence of both eighteenth- and nineteenth-century enamel formulations on objects, underscoring the need to examine all overglaze enamel colorants on porcelains before attributing the decoration to a particular time period.
 
Article
https://www.tandfonline.com/doi/full/10.1179/2047058412Y.0000000060 An experiment to investigate and quantify reliability in collection condition surveys was carried out with 33 professional conservators assessing 20 objects of various materials. Data were analysed using several reliability indices, particularly Krippendorff's alpha. The quantified reliability level (0.372 alpha) was halfway between levels considered acceptable in other fields and chance agreement. Responses demonstrated, in addition to individual differences, the main reasons for low reliability; ambiguity in survey form definitions, the broadness of the term ‘condition’, high levels of deterioration, and the professional roles of surveyors. Some existing explanations for disagreement, particularly institutional differences, were not found to have a significant effect on reliability, and object complexity and experience in conservation were found to have only a limited effect. Three factors – surveyors, objects, and survey forms – and the relationships between them, are reviewed in order to determine evidence-based recommendations for increasing reliability.
 
Article
https://www.tandfonline.com/doi/full/10.1179/2047058413Y.0000000122 This contribution discusses how embodied heritage values operate within a context of heritage sites, and tangible and intangible embodiments of what is valued as heritage. This is partly intended to recontextualize ideas of material and materiality that have recently undergone reconsideration in conservation and heritage discourse. The paper questions the claim that 'Eastern' and 'Western' philosophies of conservation are very different, and that they can be characterized as being concerned with intangible and tangible heritage, respectively. This is based on the assertion that influential preservation doctrines are as much a product of the context and practical situations as they are a product of different philosophies and cultures. Well-known examples from East and West are discussed to highlight the similarities, as opposed to the differences, in approaches. The article goes on to discuss the UNESCO definition of intangible heritage (2003), which conflates the intangible embodiment of values with the intangible values attributable to all heritage. As a way to contextualize this, the article considers embodiment of heritage values as a means to express both intangible and tangible heritage sites (since neither embodiment nor sites have to be physical). This is described by way of a simple, pre-existing communication model that moves from information source (which transmits the message) through the medium (the heritage site or object) to the audience (heritage user). These insights are intended to provide a balanced perspective that accommodates both the site and the embodied values in order to help make and justify conservation decisions.
 
Article
An account is given of the technical examination and treatment of the paintings on the 100, 000th Steinway piano (1903), which is largely gilded. The painting on the lid, executed by Thomas Dewing, is in pristine condition. The painting on the case was found to be heavily overpainted and actively flaking. Historical sources on paintings on gilded surfaces and binding medium analysis were used to establish the possible causes of paint film deterioration. The attribution of the painting on the case is discussed.
 
Article
The study of the Asian amber collection at The Metropolitan Museum of Art, New York is reviewed. Considerations for treatment material choices begin with assessing the solubility of amber and copal in organic solvents, because aqueous materials have been found to be unsuitable for treating amber. Effects of solvents were evaluated by immersing crushed samples of purchased Baltic amber and Zanzibar copal in test vials containing acetone, ethanol, deionized water, xylene, petroleum benzine, mineral spirits, Shellsol 71 and n-hexane. Results from this solvent immersion study demonstrated that the ideal material for conserving objects made from amber and copal should be soluble only in mineral spirits or petroleum benzine, because neither solvent leached out soluble molecular fractions from amber and copal. Empirical evaluation of test joins showed that 50 %(w/v) Regalrez ® 1126 in petroleum benzine imparted sufficient strength to adhere completely detached pieces.
 
Article
A study of the composition and phase distribution of the corrosion layers on three ferrous objects, excavated at K2 (Bambandyanalo), an archaeological site in South Africa, was conducted. The objective of the study was to obtain information that can contribute to conservation procedures to be performed on the iron artefacts from this site. Examination of cross sections by means of energy-dispersive X-ray spectroscopy coupled to a scanning electron microscope (SEM–EDX), X-ray powder diffraction (XRD), and micro-Raman spectroscopy revealed the same corrosion composition and structure for all the objects under study, namely an internal layer adjacent to the metal surface with ghost inclusions and an external layer containing quartz grains. The study also revealed that the presence of magnetite (Fe3O4), maghemite (γFe2O3), and lepidocrocite (γ-FeOOH) within the internal layer is the only difference between the chemical compositions of iron corrosion products within the two layers. The results also made it possible to retrace the corrosion history during burial and long-term storage.
 
Article
Zhenjiang Museum entrusted the China National Silk Museum, Hangzhou, China, to conserve gauze jacket excavated from the tomb of Zhou Yu. The gauze jacket was in fair condition when it was excavated in 1975. It exhibited serious deterioration and damage resulting from display and storage over several decades. There were over ten inappropriate repairs on both the support fabric and the lining, poorly executed, the splits having been simply stitched with thick threads which were stronger than the original weft and warp threads, and therefore capable of cutting into them and causing further damage. The deformations were greatly reduced by hand, so that the weft and warp could return to their original positions, and the jacket was then flattened under magnetic weights. Local auxiliary supports were provided for both the support fabric and the lining. Parts of the seam between lining and support fabric were unstitched, then the support fabric was supported with silk gauze of similar texture and color; and the lining was supported with Habotai silk of closely matched color.
 
Top-cited authors
David Scott
René de la Rie
  • University of Amsterdam
Jaap J. Boon
  • JAAP Enterprise for Art Scientific Studies, Amsterdam, NL
Jean Tetreault
  • Canadian Conservation Institute
Dario Camuffo
  • Italian National Research Council