A PRELIMINARY NOTE ON THE USE OF ADHESIVES AND FILLERS IN THE RESTORATION OF ANCIENT MATERIALS WITH SPECIAL REFERENCE TO GLASS

Abstract

We have reacted Georgia marble in sulfur dioxide (SO₂) enriched atmospheres and calculated the reaction rate constant. This constant was derived from surface reduction data, obtained by leaching thereaction product from samples exposed for different periods of time. Application of this constant to marble weathered in known ambient levels of sulfur dioxide (SO₂) and relative humidity, allows the prediction of the thickness of the resulting gypsum crust formed over a given period of time. We have found that the crust grows outwards due to calciumions which migrate from the interior and then react with sulfur dioxide at the sample surface. Thus, anytreatment of the sulfated marble should include the considerations that the crust only masks the marble surface and is not an integral part of the original sculpture, and that cavities exist in the underlying layer of marble from which the calcium ions were selectively depleted.     

Evaluation of disinfection techniques for the conservation of polychrome sculpture in Iberian museums

Abstract

Insect infestation is a serious problem in museum collections in Spain and Latin America. This paper investigates the efficacy of modified atmospheres as an anoxant for museum pests, using wooden objects including polychrome sculptures infested by Cerambycidae and Anobiidae species. Insects of long life cycle have been found to be very resistant to carbon dioxide atmospheres. However, inert gases such as argon and nitrogen used in plastic barrier bags effectively eliminated insects in all stages of development. No chemical alteration was observed in the treated materials, including polychromy. These treatments are in progress in a project for biodeterioration control in countries with both tropical or subtropical and Mediterranean climates.     

Pollution monitoring at heritage sites in developing and emerging economies

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-based estimations. Diffusion tube measurements of sulphur dioxide, nitrogen dioxide, and ozone from 11 sites are reported and discussed.     

刍议低碳型高校图书馆的创建

为适应社会发展的需要,低碳型图书馆将成为未来高校图书馆建设的发展趋势。文章首先列举了高校图书馆高碳高排放的现状,然后阐述了在创建低碳型图书馆的过程中所应采取的措施和注意事项,旨在提醒人们从身边的小事做起,共同保护人类的生存环境。     

Radiography of Paper

Abstract

Absorbent materials such as wood, paper and cotton stabilize the atmosphere of show-cases against the relative humidity changes caused by temperature variation and by exchange of air with the surroundings.

There are several exchange processes between the air in the case and the outside air: diffusion through porous COllstruction materials, air flow caused by temperature and pressure changes and airflow by convection in a show-case whose relative humidity differsfrom that of its environment. The air changes about once a day in show-cases made by conventional joinery techniques. The rate of exchange can be reduced to less than five volumes a year by sealing a show-case so that only one small hole is left for pressure equalization. A dust and sulphur dioxide filter can then be fitted to maintain a pure atmosphere within.

In heated rooms without air-conditioning the RH may fall dangerously low in winter. A static method of RH control for a show-case is described. This is a saturated solution of sodium bromide covered by a silicone rubber membrane.     

Rentokil Bubble in nitrogen anoxia treatment of museum pests

Abstract

The Rentokil Bubble, a commercially available, portable, fumigation enclosure which was designed for use with methyl bromide (bromomethane), phosphine or carbon dioxide, was tested for its applicability for nitrogen fumigations. The unit would be a valuable alternative for museums where a costly fumigation chamber cannot be afforded or a permanent space cannot be allocated for fumigations. The performance of two bubbles, 35m³ and 6m³, was investigated for both the oxygen transmission characteristics of the materials and the gas-tightness of the enclosure. The tests confirmed the suitability of the bubble for anoxia treatment, although some practical limitations were detected, especially the size of the unit and possible variations in quality from unit to unit. The article describes the set-up and safety considerations of a large-scale nitrogen anoxia treatment using the bubble.     

A TREATMENT FOR BLANCHING IN PAINTINGS

Abstract

The best material to be used in the restoration of a work of art is that most similar to the original. When grouting of lime-based wall paintings is necessary, lime-based grouts are the obvious choice. Compatibility is particularly important for grouting, as this is an irreversible operation. To set, lime-based grouts need air, specifically carbon dioxide, CO₂. However, in the narrow space between two delaminating layers where the grout is injected, CO₂ is not usually available in large enough quantities for this process to occur satisfactorily. To overcome this problem, extensive use has been made of hydraulic grouts, which set with water, and grouts containing synthetic or natural organic binders. A search was conducted for additives that would facilitate the setting of lime-based grouts, even at low CO₂ concentrations. In this study, a group of substances that produce CO₂ by reacting with water in an alkaline environment, esters of carbonic acid, were identified and tested to understand the kinetics of the setting process. Additives that would increase the fluidity of the grouting mixture, thus improving its injectability, were also investigated. The practical application of these grouting mixtures is illustrated by the recent restoration of Masaccio and Masolino's frescoes in the Brancacci Chapel in Florence.     

A cause of water-sensitivity in modern oil paint films: The formation of magnesium sulphate

Unvarnished twentieth-century oil paintings are often sensitive to aqueous swabbing, a method routinely employed by conservators for surface cleaning. This study proposes a connection between sensitivity and the presence of magnesium sulphate heptahydrate which has been identified on the surface of some of water-sensitive paintings. The probable source of magnesium is magnesium carbonate, an additive in some twentieth-century oil paints, which has reacted with atmospheric sulphur dioxide (SO₂). Films made using modern manufactured paints and formulations made in the laboratory were exposed to gaseous SO₂ and raised relative humidity and examined using scanning electron microscopy with energy dispersive X-ray spectroscopy and X-ray diffraction to characterize the crystalline entities. Films containing magnesium carbonate formed magnesium sulphite and sulphate hydrates. Films containing zinc oxide were also investigated. These formed zinc and sulphur containing salts. Sensitivity to swabbing with water before and after exposure was evaluated. Films that developed salts, demonstrated increased sensitivity to aqueous swabbing after exposure to SO₂. Findings suggest that increased water sensitivity may be due to a combination of the formation of hygroscopic degradation products and to weakening of the paint film due to salt-induced disruption of the surface.     

The tin-mercury mirror: its manufacturing technique and deterioration processes

Abstract

Mirrors made of glass backed with a reflective coating of tin amalgam first came into general use in the sixteenth century. Production ceased around 1900. The mirrors were made by sliding glass over tin foil flooded with mercury. The mercury reacts with tin to form a layer of crystals containing about 19wt% of mercury alloyed with the tin. The voids between the crystals are filled with a fluid phase containing about 0.5% tin in mercury. This two-phase reflective coating changes with time: the crystals grow larger and cover a greater proportion of the glass surface, while mercury slowly evaporates. In time, tiny voids appear between glass and amalgam. The fluid phase also migrates to the bottom of the mirror. Corrosion of the amalgam produces tin dioxide and tin monoxide and releases liquid mercury from the solid phase. Amalgam mirrors contribute a few micrograms of mercury per cubic metre of air in a room. Measured values have all been far below the official toxic limit of 50μgm^?3. The frames often contain drops of mercury and special precautions are necessary for safe transport, repair and disposal of the mirrors.     

Improving Environmental Conditions in the Tomb of Tutankhamen

ABSTRACT

The tomb of Tutankhamen in the Valley of the Kings, Egypt, one of the major attractions of the World Heritage Site of Ancient Thebes and its Necropolis on the West Bank of modern day Luxor, is today a destination for mass tourism. Visitors to the tomb increase relative humidity, elevate carbon dioxide levels, and encourage natural ventilation which facilitates entry of dust into the tomb. These conditions negatively impact the wall paintings and remaining artifacts in the tomb and create an uncomfortable environment for visitors. The deposition of dust inside the tomb collects on uneven wall painting surfaces, obscures their legibility and necessitates cycles of cleaning, which in turn leads to further damage. Developing environmental management strategies in the tomb to counter the effects of visitors and mitigate dust entry is an important component of the collaborative project between the Getty Conservation Institute (GCI) and Egypt’s Ministry of Antiquities (MoA) to conserve the tomb. These included implementation of a filtered-air supply and exhaust ventilation system to stabilize the interior microclimate and reduce dust in order to improve visitor comfort and contribute to the long-term preservation of the tomb.     

Determining The Presence of Photocatalytic Titanium White Pigments via Embedded Paint Sample Staining: A Proof of Principle

ABSTRACT

Twentieth century paints often contain titanium dioxide and zinc oxide based white pigments that can range from photostable to highly photocatalytic. Photocatalytic pigments can cause the degradation of paint upon UV exposure, whereas photostable pigments may be benign or can protect paintings from degradation. Hence, knowing whether or not a pigment is photocatalytic is of high importance for risk assessment and the subsequent decision making process concerning storage and exposure conditions of objects. Here we present a proof of principle, focused on titanium white paints, for an easy-to-use and low-tech application of a commercial photocatalytic activity indicator ink (PAII) on embedded paint samples or cross sections. This test determines, qualitatively, if a photocatalytic pigment is present in a white paint sample. The PAII paint sample staining application shows an obvious color change, within five minutes of UV irradiation, for paint samples containing photocatalytic pigments. A microscope with a camera and a UV source are the only necessary equipment for the application of this method. A quantitative image processing protocol is also proposed as an extension of the staining method by applying open source software analysis to measure the color change using photographs. The test was evaluated on reference paints with well-characterized pigments and applied on samples from modern paintings by Piet Mondriaan, Robert Ryman, and Lucebert, indicating the presence of harmful photocatalytic pigments in these cases. The novel application of a commercial ink on paint samples offers a simple test, not just for assessment of photocatalytic activity of titanium white pigments, but which may in future be applied for the detection of photoactive forms of zinc white and other potentially harmful semiconductor pigments in art objects.     

稀土三元催化剂对二氧化碳/环氧化合物共聚反应的催化机理研究

采用X射线光电子能谱(XPS)技术研究了二氧化碳与环氧丙烷共聚反应的稀土三元催化剂,探讨了中心金属的X射线光电子能谱与催化活性间的关系,指出稀土三元催化剂的活性中心在于配位活化后的锌氧键,稀土盐通过与烷氧基锌形成双金属桥键,改变了活性中心的电子云分布,从而提高了反应活性.     

Multifunctional nanocomposites for paper conservation

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), mechanical reinforcement (from 817–896 N/m), and UV protection. Additionally, there is a slight color difference (ΔE* = 0.8) between the treated and untreated paper. Both photodegradation and thermal degradation indicate that the paper treated with this nanocomposite (Mg(OH)₂–TiO₂–HEC) has increased stability.     

西藏档案馆藏清朝圣旨所用纸张的检测与分析研究

蜡笺纸作为中国造纸历史上一种非常重要的传统手工纸,其制作工艺如今几乎已失传。围绕蜡笺纸这种特殊的纸张所用的原料、特征等开展研究,对以蜡笺纸为载体的档案文献的保护与修复工作,以及传统蜡笺纸制作工艺的传承和复制等都具有重要的作用。本研究以西藏档案馆藏一份清朝圣旨所用的橘黄色单面洒金蜡笺纸为研究对象,利用扫描电镜(SEM)、光学显微镜、拉曼光谱仪、傅里叶变换红外光谱仪(FTIR)、X射线荧光光谱仪(XRF)等仪器或设备,对其成分和结构进行观察、检测与分析。结果表明：该纸为双层纸,原料为纯青檀皮,经过胶矾水处理,并在纸张中加入填料熟石膏;纸张正反面的着色成分均为铅丹,以动物胶为颜料的黏合剂,并进行了施蜂蜡处理。铅丹作为主要的着色成分,在一定条件下不太稳定,少部分变色生成了铅白和二氧化铅。     

清代圣旨字迹显现研究

圣旨是研究当时社会政治、经济和文化等的珍贵资料。圣旨中的字迹在长期的储存过程中褪色淡化,导致历史信息消失而失去相应的价值。对圣旨褪色的成因进行分析,进而采用显现剂纳米二氧化硅/正丁醇分散液对字迹进行显现。采用红外光谱、扫描电镜和视频接触角考察显现剂对模拟样的影响;通过色差和力学性能评价显现剂对模拟样耐老化性能的影响。结果表明,显现剂能清晰地显现模糊不清的字迹而未明显改变圣旨的形貌和组成结构;提高了圣旨基材的力学性能和耐老化性能,对圣旨的长久保存具有重要意义。该方法对同类型的字迹显现具有一定的借鉴作用。     

Public libraries: A meeting place for immigrant women?

The potential role of the public library in the lives of immigrant women is elicited by in-depth interviews with nine female immigrants to Norway from Iran, Afghanistan, and Kurdistan. The research utilizes social capital theory, the concepts of communities of practice and legitimate peripheral participation, as well as the concepts of high intensive versus low intensive meeting places. The results indicate that the library plays different roles in the different stages in the respondents' experiences as immigrants. It allows for legitimate peripheral participation when the immigrants move from observing at a distance to more active participation. The library functions as a high intensive as well as a low intensive meeting place and seems to contribute to building social capital in a variety of ways.     

Speech teacher certification: Communication and self reception: An editorial

Professor Andrew T. Weaver has a remarkable record of leadership in Speech for the last fifty years. His contributions as a writer, as a teacher and as an officer in the Speech Association of America can well serve as an example and an inspiration to people interested in teaching Speech.     

JSTOR

SUMMARY

JSTOR has become a standard offering at most U.S. universities and colleges, as well as a growing number of higher education institutions outside the U.S. This paper will track the growth of JSTOR since its inception in 1995 as an experimental digitization project to today as an archive of over 500 scholarly titles in 40 disciplines. We will consider the two threads of JSTOR's mission-to safeguard titles in a digital form, and to provide access to them as broadly as possibleand assess the value the project has provided to the academic community. In addition, there will be some discussion of future directions and challenges for JSTOR.     

Media Commons and the Sad Decline of Vancouver Indymedia

The author argues that the concept commons is a productive way of thinking about and practicing democratic and participatory media. He begins by defining media commons in such a way as to emphasize the relational and regulated nature of commons. Such a definition critiques the idea that commons are resources available to a public without limits as well as the tendency to define commons in terms of the essential characteristics of the resources in question. Next, the author's experience in the Indymedia movement is summarized to suggest that the failure of Vancouver Indymedia was due, in part, to the general inability to establish effective commons within the collective and over the website. He concludes the article by offering a survey and critique of tendencies in the formulation of the commons within wider academic and activist literatures, as well as its use in work more specifically focused on media and communication.     

Digital records as relational objects–Yuk Hui’s concept of digital objects applied to archival science

The writings of Yuk Hui, bringing together both technical and philosophical insights, present a new way of dealing with the digital. The aim of this article is to assess the use of Hui’s theories on digital objects as a critical reframing, looking at the concept of digital records in particular. Two types of ontology are needed in order to understand digital objects according to Hui: (1) ontologies which relates to the technical language and hierarchies of knowledge representation, like metadata; (2) Ontology, which is a question of being-in-the-tradition of Heidegger’s phenomenology, the understanding of what it is to be in the world. Both are needed to account for the nature of the digital object. Further, digital objects are produced and constituted through their relations, which can be divided into discursive (technical and logical) and existential (the understanding of being-in-the-world) relations. Different conceptions of digital records are discussed, in order to find commonalities and possibilities in relation to Hui’s theory. The digital record as a process of becoming, information as affordance, and temporality are related to and structured through the application of Hui’s perspective. The article ends with the contribution of a possible redefinition of digital records: a digital record is constituted and concretised as material by discursive and existential relations that taken together function as a persistent representation. Hui’s theory is suggested as a set of coordinates for further thinking and a method for critical reading of digital records.