Characterization,weathering, and protection of sandstones: The case of ‘Agro d'Ardesia’

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 effective protective material for the Agro sandstone.     

The effects of atmospheric moisture on the mural paintings of the Mogao Grottoes

The aim of this paper is to study the influence of atmospheric humidity and temperature on the mural paintings in the Mogao Grottoes of Dunhuang by measuring the weight of a simulated mural block. Under open conditions, the daily changes in the atmospheric humidity and temperature have an apparent effect on the water content of these murals. There exists an obvious water exchange between atmosphere and mural, that is, there is a ±43?g?m^?2 moisture absorption–desorption ‘breathing’ process between the two. Evapotranspiration from the tree-belt, precipitation, and extremely dry weather also have an effect on the moisture associated with a mural painting. If the cave is closed, a comparable study finds that closure can make the effects of temperature and humidity changes disappear. The mural water content in this case remains stable and the harm due to water-salt deterioration is greatly reduced. Under closed conditions, artificial condensation dehumidification and control of the cave's temperature and humidity stabilizes water activity in the mural paintings very effectively. This is a clear indication of the future steps required to protect the cave's cultural relics.     

Exposure of artists' colorants to airborne formaldehyde

Abstract

Thirty artists' colors have been exposed for 12weeks to 120ppb of formaldehyde in purified air as well as to purified air alone (control experiment). The exposure was carried out in the dark at ambient temperature (19 ± 2°C) and humidity (RH 44–52%). Color change (?E) was measured using a reflectance color analyzer after one, two, three, four, six, eight, 11 and 12 weeks of exposure. Color parameters (x, y, X, Y, Z, L*, a*, b* and ?E)"were also calculated from the 380–700nm spectra, recorded with a reflectance spectrophotometer, of unexposed colorants and of colorants exposed for 12 weeks to purified air and to formaldehyde. Regression analysis of the two data sets indicated that the color changes measured by these two methods were in excellent agreement (nearunity slopes, with correlation coefficients > 0.99). Exposure to either formaldehyde or pure air on watercolor paper resulted in little or no color change for all the colorants tested, including inorganic colorants, alizarin lakes, quinacridones, triphenyl methanes, indigo derivatives, arylamides and natural colorants such as curcumin. Formaldehyde, which is ubiquitous in indoor air, including museum air, does not appear to be a major threat to colorants in museum collections.     

A non-destructive approach using MatLab software for morphology analysis of ancient mural deterioration

The murals in Dunhuang Grottoes, a famous world cultural heritage site, are precious and unique, so research on mural surface changes and evaluation of the degree of deterioration should be non-destructive. In this study, tracking photographs of a simulated mural surface were processed with MatLab software to obtain a three-dimensional image and Z axis data, and a calculation method for quantitative analysis was also proposed. The feasibility of this approach was confirmed by simulated experiments of mural damage in the laboratory and analysis of real murals in situ. It was also applied to analysis of surface deterioration of an earthen archaeological site before and after rainfall erosion. As a simple and non-destructive approach, it could be used for the analysis of micro changes in murals or for monitoring real time surface changes at cultural heritage sites.     

Violence and identity politics: 1970s lesbian-feminist discourse and Robin Morgan's 1973 West Coast Lesbian Conference keynote address

This essay examines 1970s lesbian-feminist identity rhetorics to interrogate the exclusionary logics of visibility and gender normativity. Lesbian-feminists used such logics to exclude women living “in the closet,” performing gender in nonnormative ways, or avowing a transgender identity. Those struggles form a dynamic context to situate and critically analyze Robin Morgan's keynote address at the 1973 West Coast Lesbian Conference, “Lesbianism and Feminism: Synonyms or Contradictions?” Though Morgan's address exemplifies rhetorical violence of identity politics and transphobia within lesbian-feminist communities, I explore its radically queer possibilities to shed fresh light on persistent struggles that shape contemporary queer politics.     

MSW Interns and Public Libraries: Enhancing Services through Interdisciplinary Collaboration

While the collaborative trend among professional social workers and librarians gains traction and attention, literature about the utilization of student social workers partnering with libraries is non-existent. Over 64,000 students are currently enrolled in master-level social work (MSW) programs throughout the United States and nearly all are required to complete at least 900?hours of fieldwork. Such students provide untapped skills, knowledge, and values that can help address the broader—and very real—needs of patrons. By reaching out to MSW programs, public librarians play a critical role in helping advance tolerance for a diversity of people and much-needed services. While the professional values and ethics of both librarianship and social work have strong overlap, librarians can invite social work students to partner with them; particularly as libraries are still considered nontraditional service points. MSW students can work with libraries to expand programing, strengthen outreach, and enhance the professional development of both social workers and librarians to the benefit of marginalized patrons.     

Technical replicas of Portuguese ceramic tile bodies produced in the Oporto region in the late nineteenth to early twentieth centuries

Portugal is well known for its facades decorated entirely with ornamented glazed ceramic wall tiles called azulejos. On ageing, the tiles may detach and fall off, or deteriorate to such an extent that it becomes necessary to replicate them. Hence tile replication is a common practice in Portugal for façade restoration, but very often these new tiles do not have the same physical and/or chemical properties as the original ones. Such differences might be a factor in differential deterioration of the façades after restoration. One step toward an improvement in compatibility is to make new ceramic bodies with the same characteristics as the original ones. This study focuses on two types of glazed ceramic wall tiles from the Oporto region in Portugal: ‘calcic faience’ and pó de pedra. A total of 25 samples from the late nineteenth to early twentieth centuries were studied systematically as an attempt to improve knowledge of these materials and to create a basis for their replication. All samples were collected from facades that were under conservation/restoration at the time when sampling was performed. The original traditional ceramic bodies were analyzed by X-ray diffraction and X-ray fluorescence. Total open porosity, capillary absorption coefficient, and mercury intrusion porosimetry were also measured in order to gain knowledge on their physical characteristics in addition to their chemical and mineralogical compositions. High-temperature crystalline phases such as diopside, gehlenite, and mullite were found in the calcic faience, suggesting that the firing temperature of calcic faience bodies was within the range of 1100–1150?°C. Calcination trials were also performed in order to determine the most probable firing temperatures of the ceramic bodies. Collected data led to the assumption that the raw materials used for the ceramic bodies were kaolinitic clay, quartz sand, limestone, and talc. The raw materials for pó de pedra tiles were found to include kaolinite clay and quartz with firing temperatures estimated within the temperature range of 1150–1360?°C. Technical replicas made on the basis of these investigations were found to have the same mineralogical and capillary properties as the original tiles.     

The role of conservation in new contemporary art installations in new contexts: The case of Richard Serra's East–West/West–East in Qatar

In recent years Qatar has invested a significant sum of money on exhibitions of contemporary artists and public art. This paper discusses decision-making processes in the conservation of contemporary artworks installed in newly emerging art markets such as Qatar, where there are no established practices. In 2014, Richard Serra's East–West/West–East, an installation of four vertical plates made of weathering (Corten?) steel, which span one kilometre at heights so as to reach the level of the surrounding gypsum plateaus, was installed in the Brouq Nature Reserve near Zekreet desert, two kilometres from the sea in the western part of Qatar. The artwork is already considered by some a landmark for the isolated area. The plates have started to develop protective corrosion layers, although Corten? is not completely corrosion resistant when located near coastal sites. They have also started to bend and are heavily inscribed by visitors. Conservation of public art is complex, as site-specific artworks are linked with the landscape and defined by the relationships they develop with the public. Art installations of this magnitude demand not only conservation measures but also a management plan. The isolated location, the scale of the artwork, the aggressive environment, and the lack of supervision and monitoring of the area challenge current practices but offer an opportunity to develop methods to preserve art of site-specific art in new environments and diverse audiences. Monitoring will allow a better understanding of the interactions of visitors with the artwork and will shed light on the material's behaviour in this specific environment.     

Quantifying and visualizing change: Strain monitoring of tapestries with digital image correlation

A three-year research project at the University of Southampton (2007–2010) investigated whether monitoring techniques commonly used by engineers to assess the strength and durability of materials could be usefully applied to inform the condition assessment of historic tapestries. To date it has not been possible to obtain an objective picture of the overall condition of a tapestry; the study investigated whether it is possible to identify precursors of structural damage. The two techniques, digital image correlation (DIC) and optical fibre sensors, were used to monitor a representative wool fabric, specially woven tapestry samples, a newly woven tapestry, and historic tapestries, both in the laboratory and in situ in a historic house. This study first sets out to answer the question: can DIC be used to monitor and visualize strain in historic tapestries? It is shown that DIC can be used successfully. Secondly, it discusses the map function, a novel development which allowed the monitoring equipment to be moved, so that it could be used in situ in a historic house. Thirdly, it provides further details of the experimental work using optical fibre sensors to confirm the accuracy of the DIC technique.     

Humidity Control in Historic Buildings in Denmark

ABSTRACT

Historic buildings in Denmark have a high relative humidity (RH) all year, so the interiors are exposed to biological degradation. The acceptable range for RH is 60–70%, which is higher than the usual recommendations for museums and galleries. There are two options for humidity control: conservation heating or mechanical dehumidification. Calculation of the energy performance of a generic building was used to determine which method is the most efficient. Studies of a cottage in Liselund Park, and of two medieval churches in Hellerup and Vemb have confirmed these predictions: dehumidification is less energy consuming than conservation heating in buildings with poor thermal insulation and a moderate air infiltration rate (AER?<?0.6?h^?1). Dehumidification is suitable for historic buildings, where heating is not needed for human comfort. A condensing dehumidifier uses less than half the energy per kg water compared to an absorption dehumidifier. But it does not work at temperatures below 2°C. The combination of a condensing dehumidifier and a little heating to prevent frost is the most energy efficient solution for humidity control. These results are only valid in mild and humid climatic conditions similar to Denmark.     

Surface Investigation of Metal Threads and Solid Metals of Ottoman Textiles in the Topkapi Palace Museum

ABSTRACT

We analyzed 53 historical textile samples from a collection of caftans and brocades dating between the sixteenth and nineteenth century in the Topkapi Palace Museum (TPM) by scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX). Data were collected on the type, dimensions, elemental composition, and level of corrosion. The technique is presented in this work as an efficient and micro-destructive tool for the characterization of the structure of historical metal threads. SEM-EDX analysis for different energies was performed on a selection of gold and silver threads belonging to the historical textiles. The results were interpreted via laboratory prepared samples of gilt Ag and sulfur reacted Ag at different thicknesses for Au and Ag₂S layers respectively. A series of Au–Ag alloys for different Au/Ag ratios were prepared for comparative analysis. The threads were made of metal strips wound around a silk core. Metal wires and flat strips were also used. The use of differential energies allowed for differentiating strips and wires made of homogeneous silver and gold alloys from the ones coated with a thin gold layer. Analysis of EDX data revealed that the Au film thickness was very thin (10–60?nm). Formation of Ag₂S layers over the thin Au film as thick as 1.5?µm was taking place. Formation of thinner Ag₂S layers over non-gilt Ag suggested different reaction mechanisms for gilt and non-gilt cases.     

A Multi Proxy Investigation of Moisture,Salt, and Weathering Dynamics on a Historic Urban Boundary Wall in Oxford,UK

ABSTRACT

Boundary walls are neglected but important parts of historic urban environments, and they are often prone to serious deterioration. Understanding moisture and salt dynamics within boundary walls can help infer the causes and dynamics of deterioration. This investigation investigates the patterns of moisture, salt, and deterioration on a 300 year old limestone boundary wall in Worcester College, Oxford. Multiple methods to assess moisture and salts within and across the wall (electrical resistivity tomography, handheld resistivity-based moisture meter, paper pulp poultices, scanning electron microscopy, inductively coupled plasma optical emission spectrometry, and ion chromatography of small scale sampling of deteriorated limestone) were used in conjunction with decay mapping of both sides of the wall. The salt weathering strongly correlates with severely weathered zones at the wall and salts, mainly sulfates, seem to be the main agent of decay processes. The combined results demonstrate that the environmental influences driving stone decay can differ on a very small scale even at a comparatively simple structure like a boundary wall, and that repairs can have adverse effects if the patterns of salt and moisture dynamics are not sufficiently known.     

大档案概念的若干观点简评

本文对“大档案”概念的一些观点进行了评析,笔者认为“大档案”概念有其产生的合理性,在“大档案”概念具有多种内涵的情况下,从专业术语规范的角度看,应尽量避免使用“大档案”概念的提法,而采用较为规范、正式的专业术语。     

Providing Off-Campus Library Services by “Team”

Abstract

In contrast to many large academic libraries, Kansas State University (K-State) does not have a distance librarian. As a result, the Library Services Project Team (Team) was formed to take a fresh look at current library services for distance learners. Although the Team has been in place for over two years, and has implemented many changes, there was no mechanism for receiving formal feedback from students and faculty about these services. Because it is important to know whether services are being used, two librarians on the Team developed a Web-based survey targeted at distance faculty and students. This paper discusses the assessment project including development of the survey, the university approval process, use of an electronic in-house survey system, administration of the survey, and compilation and analysis of results.     

Hunger as Health: Culture-Centered Interrogations of Alternative Rationalities of Health

What are the experiences of health at the margins of the globe? How do the material inequities in the distributions of resources across the globe play out in the expressions of the experiences of health in the localized contexts of the global margins? In this synthesis essay, I draw upon three interconnected ethnographies conducted over several villages in West Bengal, India, over a decade-long period to explore the alternative rationalities of health that emerge at the margins. At the heart of these ethnographies is the commitment to culturally center narratives of health as hunger, foregrounding the everyday experiences of hunger and the expressions of agency at the margins in securing access to food resources. Based on the synthesis of the ethnographies, entry points are suggested for the praxis of social change communication that builds on the articulation of health as hunger and imagines localized strategies of collective resistance.     

Universitas Indonesia Archives Office as a Place for Performing Educational Practicum Activities for Students of Archives Vocational Education Program at Universitas Indonesia

Abstract

This article provides an illustration of the organizational process of a university archives management practicum course, which is based on the 321 curriculum system of the Vocational Education Program, Universitas Indonesia. This course is divided into 150?minutes of classroom study and 270?minutes of practicum activities at Universitas Indonesia Archives Office. A hands-on approach is used during the educational practicum. Assessment is carried out based on the results of a competency test (i.e., archiving documents) which is performed at the end of the first and second halves of a semester. About 55% of the students earned a good score, while 39.5% of them earned a very good score.     

Frog Voices,Whispers, and Silences: Problems and Issues in Collecting for an African Studies Library in Africa

SUMMARY

This article is an attempt to respond to two questions about discrete special African studies collections in African university libraries. First, do we need to have such collections at all? Second, if we do, how can we write collection development policies that make sense, given the present turmoil in African studies and indeed in the social sciences in general? Librarians have a responsibility to recognise that their practice cannot be value-free, and that their collections are biased by the choices made by writers, by publishers, and by themselves. Their duty, especially in Africa, may simply be to ensure that African voices are not drowned out in their collections.     

WEB2.0与图书馆2.0探析

介绍了Web1．0到Web2．0的发展历程,重点阐述了图书馆2．O概念,分析了Web2．0与图书馆2．0之间的关系。同时指出了基于Web2．0环境下的图书馆2．0的特点及相关技术和常规的应用。参考文献6。     

A study of stearyl alcohol bloom on Dan Hill PVC dolls and the influence of temperature

A study was conducted to investigate white bloom found on more than 130 polyvinyl chloride (PVC) dolls from the 1980s and 1990s produced by the Danish factory Dan Hill Plast A/S. The bloom was discovered on the dolls after 10 years of storage in a climate controlled facility with average temperature at 11–12°C and a relative humidity at 50?±?5%. Analysis of the dolls and the bloom was carried out using Fourier transform infrared spectroscopy, which revealed that the bloom consisted primarily of stearyl alcohol. Subsequent analysis with gas chromatography–mass spectrometry showed a minor presence of cetyl alcohol. It is proposed that the alcohol had been added as a lubricant to aid flow during processing. The stearyl alcohol was almost completely reabsorbed into the PVC dolls following one month storage at room temperature, suggesting that low temperature storage played a decisive role in the appearance of the bloom. It is likely that a decrease in temperature has led to a decrease in compatibility of the stearyl alcohol in the PVC compound, thus promoting its exudation. This paper also discusses an extreme bloom of white crystals on other PVC dolls of unknown provenance.     

The Changing Ecology of Tools for Live News Reporting

Broadcast news channels provide fresh, continuously updated coverage of events, in sharp competition with other news channels in the same market. The live moment is a valuable feature, and broadcasters have always relied on teams that can react quickly to breaking news and report live from the scene. Technology plays an important role in the production of live news, and a number of tools are applied by skilled actors in what can be called an ecology of tools for live news reporting. This study explores new video tools for television news, and the tinkering conducted by the reporting teams to adapt to such tools. Six journalists and photographers at broadcaster TV 2 in Norway were interviewed about their everyday work practices out in the field, and we present the findings in an analysis where six aspects of contemporary live news reporting are explored: (1) from heavy to light equipment, (2) more live news at TV 2, (3) the practice of going live, (4) the mobility of live reporters, (5) tinkering to go live, and (6) quicker pace of production. In the concluding remarks we summarize our insights about live news reporting.