Showing papers in "Studies in Conservation in 2013"
TL;DR: In this article, a systematic progression through two fundamental approaches to establish the allowable ranges of climatic variations is presented, including an analysis of the mechanical response of painted wood as a complex, multilayer system to climate variations, and an analy...
Abstract: Environmental standards for cultural heritage collections have been much debated in recent years. The interest in the issue has been driven by the growing movement towards green museums, that is, managing indoor museum environments in a responsible and efficient manner, especially in terms of reducing energy consumption and carbon emissions but at the same time maintaining high standards of collection care. Painted wood is among the category of heritage objects most vulnerable to relative humidity and temperature fluctuations. Therefore, scientific understanding of how changes in environmental conditions ultimately affect painted wood is crucial to the development of rational guidelines for the control of climate in museums and historic buildings. This review provides a systematic progression through two fundamental approaches to establish the allowable ranges of climatic variations – an analysis of the mechanical response of painted wood as a complex, multilayer system to climate variations, and an analy...
48 citations
TL;DR: In this article, changes in the temperature and humidity within the Cartoon Gallery at Knole, southern England, for the period 1770-2100 suggest a dramatic increase in favourable temperature conditions through the current century.
Abstract: Insect pests are an important source of concern in historic houses as the larval stages in particular can feed on a variety of important heritage materials, causing significant and sometimes irreparable damage to collections. Damage to wood and textiles is a special problem. The lifecycles of insects are sensitive to climate and require relatively warm conditions. There has been a significant increase in the presence of insect pests within historic houses in the early twenty-first century. The reasons may include: warmer winters, widespread use of natural fibres, less potent insecticides, and occupation of new niches indoors. The interior climate, especially increasing warmth, offers the potential for greater insect growth and survivability. Modelling changes in the temperature and humidity within the Cartoon Gallery at Knole, southern England, for the period 1770–2100 suggests a dramatic increase in favourable temperature conditions through the current century.
47 citations
TL;DR: This contribution critically examines various concepts related to damage functions in current use and makes a case to be made for more in-depth exploration of incremental and stochastic processes of degradation of heritage materials and structures, and the associated values, with a view towards developing more damage functions.
Abstract: This contribution critically examines various concepts related to damage functions in current use; it does not represent a comprehensive review, however. In heritage science, damage functions can be defined as functions of unacceptable change, dependent on agents of change. Unlike in other domains of science, the reference to unacceptable change implies that a value-based decision needs to be applied to the analytically determinable change, or dose–response function. Since there are a number of values associated with heritage, there can be a number of damage functions describing one and the same physical or chemical process of change. For practical reasons, it is thus useful to decouple the value function from the dose–response function, as the latter can be independently deduced (empirically or experimentally). While the behaviour of single materials and objects is often modelled deterministically, the probabilistic approach can be used to describe the degradation of complex structures, e.g. buil...
43 citations
TL;DR: In this article, the degradation of Emerald green (Cu(C2H3O2)2·3Cu(AsO2), copperacetoarsenite) is investigated.
Abstract: Descente des vaches (1836) by Theodore Rousseau in the Mesdag Collection in The Hague is barely readable and its paint layers are in poor condition. The surface of the painting is strongly deformed and cracked, the whole painting has darkened and especially the greens have lost all or most of their colour resulting in brown passages. Large passages of the painting that were painted with multiple thick and medium-rich layers have darkened dramatically. This paper proposes that the degradation of Emerald green (Cu(C2H3O2)2·3Cu(AsO2)2, copperacetoarsenite) – the main green pigment used in this painting – is a significant factor in the cause of the darkening. Electron backscatter images reveal that the Emerald green particles are shown different degrees of degradation: from partially to completely disintegrated. Elemental maps show that arsenic is distributed throughout the paint cross section, with relatively higher concentrations around iron- and aluminium-containing particles, and in the varnish la...
31 citations
TL;DR: In this article, an electronic unit measures and records changes in the electrical resistance of a thin metal track applied on an insulating substrate, if the metal corrodes, the effective cross sectional area of the track decreases and electrical resistance increases.
Abstract: A system for continuous monitoring of atmospheric corrosivity has been developed. An electronic unit measures and records changes in the electrical resistance of a thin metal track applied on an insulating substrate. If the metal corrodes, the effective cross sectional area of the track decreases and the electrical resistance increases. Sensors made of silver, copper, iron/steel, zinc, lead, tin, aluminium, bronze, and brass at thicknesses from 50 nm to 250 µm were tailored for environments with different corrosivities. The developed technology proved capable of providing high sensitivity, allowing for real-time corrosion monitoring even in low-corrosive indoor cultural heritage facilities. Laboratory tests showed good reproducibility with the standard deviation of parallel measurements at less than ±20% for metals which corrode uniformly in the tested environments. Several examples selected from a broad testing programme in partner museums, libraries, and other institutions show successful applic...
30 citations
TL;DR: In this paper, the authors characterized Fe(II) sulphides and their by-products from 13 waterlogged samples by environmental scanning electron microscopy, micro-Raman spectroscopy, and X-ray diffraction.
Abstract: Wet organic archaeological materials extracted from seawater may suffer damage as a result of degradation influenced by micro-organisms. One of the most common phenomena is indirectly induced by sulphate-reducing bacteria (SRB). Due to their metabolic activity in anoxic conditions, SRB generate hydrogen sulphide from sulphate ions present in seawater. When steel items are in contact with organic matter in presence of sulphides, corrosion of the metal leads to the precipitation of Fe(II) sulphides. These phases are responsible for dramatic post-excavation damage: their oxidation during storage or exhibition in museums leads to the formation of voluminous crystals, which may cause cracking and crumbling, and lead to the production of sulphuric acid. In order to characterize Fe(II) sulphides and their by-products, 13 waterlogged samples were analysed by environmental scanning electron microscopy, micro-Raman spectroscopy, and X-ray diffraction. Experiments were performed on untreated wood fragments, ...
28 citations
TL;DR: In this article, a group of ancient Greek red-figure vases and vase fragments in the collection of the Harvard Art Museums and the Worcester Art Museum were examined using reflectance transformation imaging and three-dimensional laser scanning confocal microscopy.
Abstract: The relief and contour lines on a group of ancient Greek red-figure vases and vase fragments in the collection of the Harvard Art Museums and the Worcester Art Museum were examined using two surface examination methods – reflectance transformation imaging and three-dimensional laser scanning confocal microscopy. These methods helped characterize the lines and answer questions regarding tools, techniques, and production sequence used by Greek vase painters. This research also incorporated fabricated mock-ups to gain a better understanding of the ancient technology and in so doing confirmed that the relief lines were not produced by an extruded method, but with a brush made with only a few hairs, termed linierhaar as first proposed by Gerard Seiterle in 1976. Furthermore, it was discovered that not one but two distinct types of relief lines exist on these ancient vases: the laid line (proposed by Seiterle) which has a characteristic ridged profile, and the pulled line (proposed in a previous publica...
25 citations
TL;DR: In this article, the authors measured post-treatment corrosion rates in accelerated corrosion environments to identify the impact of removing chloride ions on corrosion rate, and showed a significant linear correlation between chloride content and weight gain.
Abstract: Although desalination of archaeological iron reduces its chloride concentration and enhances object stability, the reduction in corrosion rate that this produces has never been quantified. This study measures post-treatment corrosion rates in accelerated corrosion environments to identify the impact of removing chloride ions on corrosion rate. Thirty-five archaeological iron nails, treated individually in either alkaline sulphite or nitrogen-deoxygenated sodium hydroxide, were exposed to 75°C and 75% relative humidity together with 31 untreated objects from the same archaeological sites. Object weight change and visual examination of physical change before and after the test period were used to monitor corrosion. 77% of treated objects showed no weight gain and no visible signs of corrosion, while 90% of untreated objects did corrode. The impact of chloride on corrosion of untreated objects was clearly established by a significant linear correlation between chloride content and weight gain. Treated objects with <400 ppm chloride content showed no corrosion behaviour. Corrosion of treated objects was attributed to incomplete treatment: 93% of objects treated to <5 mg/l Cl− in the final solution bath displayed no corrosion behaviour. Based on these results, desalination of iron objects to enhance their stability offers a valuable option for reducing corrosion rates of archaeological iron, which should increase object lifespan. The results also raise the question of whether low levels of post-treatment residual chloride produce corrosion of any significance. Answering this will be an important step forward for managing the preservation of archaeological iron.
25 citations
TL;DR: In this article, high amounts of oxalic acid have been found along with a low pH and low molecular weight cellulose deep in the wood timbers of the Swedish warship Vasa.
Abstract: The oak timbers of the Swedish warship Vasa are deteriorating. High amounts of oxalic acid have been found along with a low pH and low molecular weight cellulose deep in the wood timbers. The iron- ...
16 citations
TL;DR: In this paper, issues with air pollution monitoring at heritage sites in developing and emerging economies, from management to technical, are reviewed, and different possible solutions are reviewed and their appropriateness discussed.
Abstract: Air quality is an important factor in the preservation of cultural heritage. Systematic air quality assessment is a requirement in most heritage conservation plans. However, apart from temperature and relative humidity, air pollution, which is another air quality parameter, is less often monitored. This is the case especially, but not only, in developing and emerging economies where the lack of air pollution data is worrying. In this paper, issues with air pollution monitoring at heritage sites in developing and emerging economies, from management to technical, are reviewed. Questionnaire responses from over 20 sites in Africa, Asia, and Latin America reveal that about eight out of ten sites have not yet considered pollution data. The responses also show that cost is not the only obstacle but that lack of awareness and insufficient technical expertise are also significant issues. Different possible solutions are reviewed and their appropriateness discussed. They range from systematic monitoring to model-b...
14 citations
TL;DR: In this paper, the use of nanoparticles of titanium dioxide (TiO2) and magnesium hydroxide (Mg(OH)2) associated with hydroxyethylcellulose (HEC) to inhibit acidification, photo-induced degradation, and biodeterioration of paper was reported.
Abstract: Upon aging, paper documents and books become progressively damaged. Paper deacidification is a fundamental conservation intervention. In this study, we report on the use of nanoparticles of titanium dioxide (TiO2) and magnesium hydroxide (Mg(OH)2) associated with hydroxyethylcellulose (HEC) to inhibit acidification, photo-induced degradation, and biodeterioration of paper. With the aid of ultrasound, Mg(OH)2 nanoparticles with a narrow size distribution can be obtained through homogeneous precipitation in water. Furthermore, to demonstrate the efficacy of the nanocomposite and the performance of treated and untreated paper, photo- and thermal-induced degradation is discussed. The results show that using the controlled double-jet precipitation (CDJP) it is possible to synthesize Mg(OH)2 particles with a narrow size distribution (18–87 nm). The nanocomposite of Mg(OH)2–TiO2–HEC increases the durability of paper by imparting fungal growth resistance (D = 34.6 mm), moderate alkalinity (pH = 8.4), mech...
TL;DR: The severity of cracking is influenced by a combination of factors, including the amount of cold-work in the silver and the burial environment as mentioned in this paper, which can induce high stresses, particularly in hollow, thin-walled, and incompletely filled-in artefacts.
Abstract: Six cases of ancient silver embrittlement by corrosion are discussed with respect to evidence for stress corrosion cracking. Both intergranular and transgranular cracking can occur, depending on whether there is retained cold-work in the silver. The severity of cracking is influenced by a combination of factors, including the amount of cold-work in the silver and the burial environment. The burial environment is important for two reasons. Firstly, the soil weight can induce high stresses, particularly in hollow, thin-walled, and incompletely filled-in artefacts. Secondly, grave burials can result in more aggressive soil environments owing to high salinity from body decomposition.
TL;DR: In this article, a practical photographic lifetime calculator is presented, integrating dose-response functions with end-of-lifetime considerations, based on a value-based psychophysical approach.
Abstract: Colour photographs are among the most vulnerable materials in archival collections, making the development of tools for assessment of their lifetime in storage of particular interest. However, for this to be possible it is necessary to have a holistic understanding of what affects the lifetime of an object. Based on the existing knowledge of the effect of environmental conditions and material properties on lifetime of prints, this work focuses on the determination of end-of-lifetime using a value-based psychophysical approach. This research, carried out using a series of stakeholder workshops, showed that while assessor background does not significantly affect the end-of-lifetime determination, the nature of the images does. Isochrones, curves linking points of equal lifetime at paired environmental conditions, are defined. Based on these, a practical photographic lifetime calculator is presented, integrating dose-response functions with end-of-lifetime considerations. This tool, based on stock mo...
TL;DR: In this article, a combination of Fourier transform infrared spectroscopy (FTIR) and gas chromatography-mass spectrometry (GC-MS) allowed the components of the paint media to be characterized.
Abstract: This study describes the examination and analysis of four mixed media paintings from the 1960s and 1970s by Canadian artist Jack Chambers (1931–1978). The documentary evidence about his materials and methods is summarized and compared with the results of analysis of multilayer paint samples. The combination of Fourier transform infrared spectroscopy (FTIR) and gas chromatography-mass spectrometry (GC-MS) allowed the components of the paint media to be characterized: ortho-phthalate alkyd resins, iso-phthalate alkyd resins, drying oils, dammar, Pinaceae resin, and turpentine were identified in varying proportions. Many pigments and fillers were identified by FTIR and Raman and are enumerated. The effect that Chambers’ complex technique has had on the aging and degradation of the paintings is discussed. The severe cracking of the paint layers in one of the four paintings may be the result of a high proportion of dammar and turpentine diluent mixed with the alkyd paint and may also be related to the ...
TL;DR: Although measurable criteria supplied apply only to the three named New Zealand plant species, this paper provides methods that could be applied to the identification of other aged plant leaf material.
Abstract: This work investigates the use of micro-computed tomography (micro-CT) for identification of New Zealand plant leaf material from artefacts. Micro-CT was explored as a result of difficulties in preparing transverse sections from aged plant material artefacts to compare with reference slides for microscopic identification of plant species. Plant names in te reo Māori (Māori language) are followed by the English name and botanic name, and are subsequently referred to by Māori names. The three plants investigated (harakeke, New Zealand flax, Phormium tenax, J. R. Forst & G. Forst; tī kōuka, cabbage tree, Cordyline australis, (Forst.f.) Endl,; kiekie, Frecinetia banksii A.Cunn.) were/are commonly used by Māori for the manufacture of objects often found in cultural institutions. Contemporary and historical specimens (from artefacts) of plant leaf material were investigated. Contemporary specimens were viewed using micro-CT and showed identifiable features compared with micrographs of transverse section...
TL;DR: In this article, the authors present a review of the available information for re-decorating historic houses to demonstrate the effects of time, having been subjected to the surrounding environment within the property.
Abstract: Furniture collections can be key in the interpretation of historic houses to visitors, providing a link to their own homes and making houses seem inhabited. The ornate and highly decorative surfaces reflect not only the aesthetic taste of the period, for example chinoserie inspired lacquerware, but also the design and craft expertise and manufacturing skills required to produce the objects. These surfaces can demonstrate the effects of time, having been subjected to the surrounding environment within the property. For highly decorated surfaces, such as veneer and marquetry, this can include loss of material, lifting veneers, fading of wood and its finishes, along with cracks, splits, flaking, and warping. Preventive conservation seeks to minimize the risk to collections by optimizing the display and storage parameters. However, research on these materials to determine the optimal display conditions can be limited, insufficient, or even entirely absent. This review presents the available information for re...
TL;DR: The Kitora tumulus has beautiful mural paintings which were executed directly on a very thin layer of plaster in the stone chamber, and the paintings were found to be likely to fall off the wall with a casual touch or stimulation.
Abstract: The Kitora tumulus, which is thought to have been built around the late seventh to early eighth century, has beautiful mural paintings which were executed directly on a very thin layer of plaster in the stone chamber. When the paintings were found, the plaster was partly detached from the stone wall and the murals were therefore considered to be likely to fall off the wall with a casual touch or stimulation. Therefore, it was decided to detach the mural paintings and to store them flat and under controlled environmental conditions. This was initiated immediately after the excavation of the tumulus in 2004. However, fungal growth and biofilm development were observed within the stone chamber during the relocation work. In 2005, small holes containing black substances were observed on certain areas of the ceiling plaster, and following investigation an acetic acid bacterium, Gluconacetobacter sp., was isolated from the black substances. The bacterium was also isolated from the ceiling, floor, and ea...
TL;DR: De Sousa and Rodrigo as discussed by the authors assessed the ageing of polyvinyl acetate, PVAc, paints and found that in most cases the emulsion employed was based on a pVAc homopolymer and that the paints are in good condition with no signs of deterioration.
Abstract: The ageing of poly(vinyl acetate), PVAc, paints was assessed in works by Ângelo de Sousa and Joaquim Rodrigo. The materials and techniques of the artists were studied through interviews and by chemical analysis. They were both using PVAc in 1961, preparing their own paints by mixing commercial PVAc emulsions with selected colorants. It is shown that in most cases the emulsion employed was based on a PVAc homopolymer and that the paints are in good condition with no signs of deterioration. Finally, this study allowed a comparison to be made between paint samples aged naturally and those aged under artificial conditions. This means that these artificially aged samples may be used as reference materials for PVAc paintings. Both sets exhibit molecular infrared fingerprints that are undistinguishable from an unaged PVAc, suggesting little chemical degradation over 50 years of natural ageing.
TL;DR: In the late 1800s, pictorialist photographers favored a diversity of photographic techniques, including the gum dichromate process, and the definitive identification of this process has proven to be a challenge due to many variations and intermingling of techniques used by photographers of this period as discussed by the authors.
Abstract: In the late 1800s, pictorialist photographers favored a diversity of photographic techniques, including the gum dichromate process. Sometimes superimposed over other photographic images such as platinum and silver prints, the gum dichromate process utilizes a light-sensitive mixture of gum arabic, pigment, and a potassium dichromate solution hand-applied onto a sheet of paper and exposed to light while in direct contact with a negative. The definitive identification of this process has proven to be a challenge due to many variations and intermingling of techniques used by photographers of this period. This research began with a search through the historic literature, followed by the creation of test samples based on historic recipes, and the X-ray fluorescence analysis of these tests. The identification of pigments and the presence of chromium have been associated with the gum dichromate or other dichromated colloid processes in the past. Research results reveal that the presence of chromium may h...
Abstract: (1988). PERMANENCE OF WASHI (JAPANESE PAPER) Studies in Conservation: Vol. 33, Kyoto Congress Preprints: The Conservation of Far Eastern Art, pp. 1-4.
TL;DR: The long-term stabilization of marine archaeological iron, whether cast or wrought, continues to challenge conservators responsible for treatment of this material as discussed by the authors, and this problem is particularly acute with corroding cast iron objects that have formed thick, fragile, and highly unstable corrosion layers.
Abstract: The long-term stabilization of marine archaeological iron, whether cast or wrought, continues to challenge conservators responsible for treatment of this material. Results and observations obtained from past treatments highlight the daunting, prolonged, and laborious efforts required to desalinate large and complex ferrous artifacts recovered from the ocean. In general, the higher an artifact's chloride level, the less stable it is. Consequently, any stabilization treatment must involve the removal of as much Cl−1 as possible without affecting the integrity of the corroded artifact. This problem is particularly acute with corroding cast iron objects that have formed thick, fragile, and highly unstable corrosion layers. Over the course of the twentieth century, conservators have used a variety of techniques in an attempt to mitigate the negative effects of chloride ions on iron artifacts and prevent disintegration. In spite of early promise, each of these stabilization techniques has significant di...
TL;DR: In this article, the performance of polymeric products used for the protection of a typical Italian sandstone, the ‘Agro d'Ardesia’, used mostly as cladding, paving, roofing, and building material was compared.
Abstract: The conservation of roofing and cladding materials has both environmental and cultural heritage bearing. Our research aimed at comparing the performances of some polymeric products used for the protection of a typical Italian sandstone, the ‘Agro d'Ardesia’, used mostly as cladding, paving, roofing, and building material. These products belong to three different classes: polysiloxanes, acrylics, and fluoropolymers. In addition, an acrylic–silicone mixture was chosen for testing. After the application onto the Agro sandstone by capillary absorption, both efficacy and durability were assessed. Particularly, two types of weathering tests were performed to check the stability over time of the protective products: the exposure to ultraviolet radiation in a climatic chamber and the ageing by exposure to acid rain, expressly designed to represent realistically natural and anthropogenic changes. Detailed information on treatment performances was obtained. The polysiloxane was shown to be the most effectiv...
TL;DR: In this paper, 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.
Abstract: 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 microRaman 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.
TL;DR: In this article, an experiment to investigate and quantify reliability in collection condition surveys was carried out with 33 professional conservators assessing 20 objects of various materials, using several reliability indices, particularly Krippendorff's alpha.
Abstract: 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 deter...
TL;DR: The Vienna cityscape has retained its nucleus of the Roman fort through Medieval times to the present as discussed by the authors, and its outlines changed again with the building of new fortifications in the sixteenth and seventeenth centuries.
Abstract: The Vienna cityscape has retained its nucleus of the Roman fort through Medieval times to the present. Since the thirteenth century it has been enlarged, and its outlines changed again with the building of new fortifications in the sixteenth and seventeenth centuries. Gardens spread around the perimeter during the eighteenth century until the building of the new Ringstrase after 1857 replaced the dismantled bastions. Vienna's cathedral, the Court, palaces, public and private houses with characteristic built features including details such as pavings, lighting or railings, symbolic ornaments on buildings or in public spaces, all illustrate aspects of the decorative. In 1864–1874 the first museum and school for applied arts in mainland Europe set new standards for techniques and design of decoration. In 1889 Camillo Sitte in his book on urban architecture promulgated the idea of retaining historic details in growing cities, and regarding them as artistic creations. In 1895–1905 plans to adapt the na...
TL;DR: Basketry artifacts fabricated from spruce and cedar limb wood and root and the inner bark of yellow and red cedar have been found in water-saturated archaeological sites in the Pacific Northwest since the mid-twentieth century as mentioned in this paper.
Abstract: Basketry artifacts fabricated from spruce and cedar limb wood and root and the inner bark of yellow and western red cedar have been found in water-saturated archaeological sites in the Pacific Northwest since the mid-twentieth century. These artifacts range in age from a few centuries to more than 5000 years old. While these materials retain their overall physical structure due to burial in an anoxic environment they are degraded on the cellular level. Experiments and treatments performed by archaeologists and conservators over the past 50 years have attempted to stabilize these degraded structures and minimize splitting, crumbing, and distortion of the woven structures as they dried. Many of these tests and treatments are published in out-of-print conference proceedings or remain unpublished in conservation lab records. This review of tests and treatments as well as a current condition assessment of several collections brings this information together for the first time and allows conservators an...
TL;DR: The history of the production of electrotype copies is discussed in the context of the Victorian demand for reproduction of art of all kinds utilizing plaster of Paris, photographs, copies of old prints, as well as electrotypes, predominantly of copper as discussed by the authors.
Abstract: The history of the production of electrotype copies is discussed in the context of the Victorian demand for reproduction of art of all kinds utilizing plaster of Paris, photographs, copies of old prints, as well as electrotypes, predominantly of copper. The philosophical reasons for the valuing or devaluing of electrotype and other copies are discussed. Electrodeposition of metals was used for an extraordinary number of different purposes in the Victorian period, and the general craze for electrotypes made their production very popular, being produced by men and women alike of many different backgrounds. By the Edwardian era, the need had subsided and an art historical reaction to the concept of copies had begun, with photography becoming more common. Examples of the use of electrotypes for photographic tinthotypes, as well as forgeries, discovered during conservation assessment at the Getty Museum on a plain Roman cased mirror which had been augmented by an electrotyped profile head addition, and...
TL;DR: In this paper, the impact of relative humidity on jades by enclosing the samples under constant relative humidity (RH) of 32, 49, 61.5, and 81.7% at the same temperature of 40 −± 0.1°C for 160 days was examined.
Abstract: This paper examines the impact of relative humidity on jades by enclosing the samples under constant relative humidity (RH) of 32, 49, 61.5, and 81.7% at the same temperature of 40 ± 0.1°C for 160 days. The simulated samples were pure and dense tremolite jade and serpentine jade, impure tremolite jade and serpentine jade containing some calcite, and serpentinized calcite, which are all common materials of ancient jade found in archaeological excavations. All samples were characterized through particle-induced X-ray emission and a glossmeter. The degree of deterioration proved to be greater in impure materials than in pure ones. The best RH to conserve various kinds of materials differs: for pure tremolite and serpentine, all of the RH levels are equal; for impure tremolite with some calcite, 61.5 and 81.7% were superior; for impure serpentine with some calcite, the highest RH (81.7%) was best; and as to the serpentinized calcite, there is no clear conclusion as yet and further research is needed.
TL;DR: In this article, the authors present le bilan de l'emploi d'insectes auxiliaires, the guepe parasitoide Trichogramma evanescens, dans le cadre de la lutte contre une infestation de mites des vetements Tineola bisselliella au sein des reserves du Musee d'Ethnographie de Geneve.
Abstract: L'article fait le bilan de l'emploi d'insectes auxiliaires, la guepe parasitoide Trichogramma evanescens, dans le cadre de la lutte contre une infestation de mites des vetements Tineola bisselliella au sein des reserves du Musee d'Ethnographie de Geneve. Apres deux saisons de deploiement d'auxiliaires et l'observation de la presence de mites au moyen de pieges a pheromone, il a ete conclu que les auxiliaires etaient inefficaces en raison de leur manque de mobilite. En outre, la distribution d'insectes auxiliaires a necessite une campagne importante de nettoyage de l'ensemble de la collection concernee afin d'eliminer les auxiliaires morts. L'infestation de mites a finalement ete maitrisee par les moyens traditionnels d'hygiene, de recherche meticuleuse de foyers, et de traitement par anoxie.