The evaluation of selected poly(vinyl acetate) and acrylic adhesives: A final research update

Abstract

The final report on the Canadian Conservation Institute's poly(vinyl acetate) and acrylic adhesive research is given after 25–27 years of dark aging and 12–15 years of light aging. A total of 27 poly(vinyl acetate) and 25 acrylic adhesives were tested for pH, volatile emissions (mostly acetic acid), flexibility, strength, and yellowing after aging. In 1996, the work was first published after three to five years of aging data had accumulated. Measurements for pH, yellowing, strength, and flexibility were recently repeated again and these results are reported here. These new data points are reported to provide insight into the effect of these longer aging periods on the products included in the study. As well, the most stable (according to set criteria) poly(vinyl acetate) and acrylic adhesives tested are revealed, which, except for a few products, do not differ greatly from those reported in 1996.     

Visual effects of selected biocides on easel painting materials

Abstract

This paper reports on the results of experiments to test for visual changes to paint systems after biocidal treatments, using a statistical binary procedure. Four biocides were selected, two of which are fungicides—a quaternary ammoniumorganotin mixture (BioMet 66^®)in distilled water and an orthophenylphenol (Lysol^®) in a spray— and two of which are fumigants—sulfuryl fluoride (SO₂F₆), a gas (Vikane^®), and nitrogen gas (N₂) (as an anoxant). The procedure used to assess the effect of the biocidal treatments was a random field visual scoring regimen by two paintings conservators. The tests were conducted on 30 combinations of linen, rabbitskin glue size, lead white oil ground and oil-based paints. The visual assessment procedure provided information on color change, gloss change, blanching, topography change and precipitation. The results indicated that Vikane adversely affected 10 of 11 pigment systems; Lysol adversely affected six of 11 pigment systems; BioMet 66 had a minor effect on four of 11 pigment systems; and nitrogen had no visible effect on any sample. The visual technique provided a quick and broad method for assessment of non-subtile visual changes.     

Stabilization of Iron Artifacts from Kaman-Kalehöyük: A Comparison of Chemical and Environmental Methods

Abstract

Testing of chemical stabilization treatments and desiccated and anoxic storage microclimates for the protection of archaeological iron stored in unsuitable climatic conditions was carried out by the conservation department of the Japanese Institute of Anatolian Archaeology at the Kaman-Kalehöyük excavation in Turkey. The chemical stabilization treatments involved alkaline sulfite, barium hydroxide and sodium hydroxide. Environmental stabilization was explored using RP-A oxygen scavengers in Escal^® bags as part of the Revolutionary Preservation System (RP System^®) manufactured by Mitsubishi Gas Chemical Company, Inc. The efficiency of the chemical treatments was examined by comparison with mechanically cleaned iron objects. The efficiency of the storage systems was determined by comparing the chemically and non-chemically treated objects in the RP System^® using RP-A scavengers and in polyethylene ziplock bags containing silica gel. The efficiency of these treatments and storage systems was examined and assessed at Kaman after a period ranging from 7 to 9 years. The anoxic and desiccating properties of the RP System^® resulted in superior protective qualities over polyethylene bags with silica gel. The RP System^® compensated for inadequate chemical stabilization and protected iron that had not been chemically stabilized.     

Original and reformulated BEVA® 371: Composition and assessment as a consolidant for painted surfaces

Abstract

Many natural and synthetic products have been used for the consolidation of paint layers, but none have been thoroughly tested for this application. This is apparent for most of the synthetic and semi-synthetic adhesives for conservation, many of which are pure polymer resins and dispersions adapted from other industries. They were not specifically formulated with the appropriate properties for conservation, nor do they take advantage of some of the more recent developments in adhesive technology. BEVA^® 371 is unique among adhesives used for consolidation treatments, as it is a multi-component mixture and was designed specifically for the conservation field using the best technology available at the time. However, the main focus of the research was its application as a lining adhesive. Thus, optical properties and stability, specifically color stability, were not thoroughly evaluated even though some lining applications that were first recommended could have benefited from this type of investigation. This paper will discuss the development of BEVA^® 371, the chemistry, and roles of each component, and address a practical concern about the tack behavior of its replacement formulation, BEVA^® 371b.     

The Ephemeral,the Essential and the Material in the Conservation of Contemporary Art: Decision-Making for the Conservation of a Work of Art Made with Butterfly Wings

This article presents the intervention process carried out on a work of art created by artist Yolanda Gutiérrez Acosta, using a series of ephemeral materials such as butterfly wings and agave thorns. The work, an installation from 2002, is entitled ‘Efímeras’ (‘Ephemera’) and consists of 12 flowers mounted on acetate sheets and attached to the same with vinyl acetate copolymers and acrylic acid esters (Mowilith®). These flowers are installed on the floor in a bed of dried flowers. The conservation of contemporary art can lead to some previously unimaginable problems for restorers. Current works of art are somewhat material in nature, but they also have a conceptual dimension that is essential for their artistic interpretation. The artist’s participation in the decision-making process prior to the restoration was quite useful. The passage of time, its effect on the work, and the need to understand the possibility of the demise and destruction of the work were implicit as of the onset of its creation, such that, according to the artist, we are forced to reflect upon the possibilities of its future state.     

Investigation of Effects of Fumigants on Proteinaceous Components of Museum Objects (Muscle,Animal Glue and Silk) in Comparison with Other Non-chemical Pest Eradicating Measures

Abstract

Fumigant effects on protein-based materials were examined and compared with those of non-chemical pest-eradicating measures. The responses to six fumigants – methyl bromide, methyl iodide, ethylene oxide, methyl bromide/ethylene oxide mixture, propylene oxide and sulfuryl fluoride – were examined with two controlled atmospheres and a range of thermal treatments, using protein electrophoresis, Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), thermal microscopy (T_mic), thermal gravimetric analysis (TGA), amino acid analysis and X-ray fluorescence (XRF) spectrometry. A model soft-tissue protein, freeze-dried chicken muscle, was shown to be affected by some fumigants, especially methyl bromide, methyl iodide and sulfuryl fluoride (Vikane^®). This is the first detailed evidence of chemical alterations of a protein material by fumigants under the common treatment conditions for museum use, especially showing a possibility of protein modification by purer grade sulfuryl fluoride whose definite mechanism of toxicity is still unknown. Residual bromine and iodine were clearly detected by XRF in the muscle specimen that had been fumigated with either methyl bromide or methyl iodide respectively, even after a single fumigation several years earlier. On the other hand, significant change in characteristics of animal glue and new and deteriorated silk textiles were not detected. However, residual bromine and occasionally iodine also were detected in the glue and silk samples fumigated by methyl bromide or methyl iodide several years earlier.     

Dimensional Stability and Moisture Properties of Gap-Fillers Based on Wood Powder and Glass Microballoons

ABSTRACT

Conservation of wooden objects exposed outdoors is extremely difficult and complex due to their constant exposure to fluctuating weather conditions and biological degradation. Filling the gaps in such objects requires the use of specific materials that in particular can adapt to changes in wood dimensions in response to humidity variations. Various materials have been used so far for filling voids in wooden artefacts but none of them was entirely suitable. Therefore, the authors have attempted to provide the basic characteristics of the selected commonly used filling materials based on pine wood powder or glass microballoons as fillers and Paraloid® B-72, Klucel® G, or glutin glue as binders, as the first step in research aiming at developing new and more appropriate gap-fillers. Special attention was paid to the dimensional stability of filling materials upon drying and exposure to water vapour and liquid water. The overall results indicate that among the examined fills those consisting of Paraloid® B-72 and glass microballoons revealed best properties as they were relatively dimensionally stable upon drying and exposure to moisture – despite high absorption of water – and were quite easy to finish. Generally, better properties were observed for filling materials containing higher concentrations of adhesives and these materials will be modified in the next step of the research. Since the main drawbacks of the examined gap-fillers were low water resistance, poor dimensional stability upon drying or exposure to water vapour or liquid water, and fragility or friability, future research into their modification will head towards improvement of the above-mentioned properties.     

细菌纤维素对纸质档案的加固性能评价

本研究以细菌纤维素作为纸质档案的加固剂,制备不同质量分数的细菌纤维素水分散液,均匀喷涂在纸张上,对纸张进行加固处理。采用万能材料试验机、耐折度仪、扫描电镜、柔软度仪、光泽度仪、厚度仪、非接触式分光光度仪、pH计和超景深显微镜等,表征细菌纤维素对纸质档案的加固作用;利用TG/DTG热分析仪和红外光谱仪,表征细菌纤维素对纸质档案微观结构的影响。结果表明,质量分数为0.3%的细菌纤维素加固纸张后,纸质档案的机械强度提高最明显,加固纸张的效果最好;细菌纤维素在加固纸张的同时增加了纸张的稳定性,且没有改变纸张的微观结构。     

Early aqueous dispersion paints: Portuguese artists’ use of polyvinyl acetate, 1960s–1990s

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.     

Solvent Vapour Use – The Unintended Consequences in Textile Conservation

ABSTRACT

The impact of solvent vapour from two solvents, acetone and industrial denatured alcohol (IDA), commonly used in adhesive reactivation in textile conservation, when applied to artificially soiled silk fabric through either Gore-Tex^® or Reemay^® membranes for exposure times of either 1 or 3 min, was measured using microscopy and ImageJ to monitor the movement of the solid particulates of the soiling, and Fourier transform infrared spectroscopy with attenuated total reflectance (FTIR-ATR) to monitor the movement of the oily components. Analysis using these techniques successfully showed the movement of large particulates through the textile and a decrease in the presence of oil. Analysis with FTIR-ATR showed that the application of solvent vapour by a poultice method produces more than just a surface change and the vapour can penetrate far enough into the fibres to cause a change in the level of oil through the entire textile. The results showed that the solvents and barrier membranes have characteristic differences which impact on the changes on the soiling. The application of acetone produced a greater change in the movement of oil on the front and back of the samples than the application of IDA, while a comparison between the barrier membranes showed a greater change occurring in the level of oil with the use of Gore-Tex^® rather than Reemay^®. The time of exposure to solvent vapour made little difference to the changes to the textile soiling. Quantitatively significant results were gathered from analysis of the changes in the oil measured with FTIR-ATR, and qualitative changes in the large particulate soiling, demonstrating the potential usefulness of ImageJ open access software in future historic textile soiling monitoring studies.     

‘Tales of Japan’: a travelling exhibition of Japanese art from the New York Public Library

Abstract

Acrylic polymer dispersions, regularly used as artists' media or varnishes, were monitored for the development of yellow discoloration under natural aging conditions for a period of two years. Films of a number of water-based acrylic artists' media were kept under visible light of either moderate (150 lux) or low (50 lux) intensity (cycled on 10 hours per day) and were compared to films kept in dark storage, which have been observed to yellow. Results after two years show that exposure to visible light at 150 lux effectively prevented film discoloration in a number of products, and seemed at least to slow the rate of yellowing in others. Exposure to low-intensity (50 lux) lighting was found to be less effective in preventing this yellowing.     

Modeling actions of PubMed users with n-gram language models

Transaction logs from online search engines are valuable for two reasons: First, they provide insight into human information-seeking behavior. Second, log data can be used to train user models, which can then be applied to improve retrieval systems. This article presents a study of logs from PubMed^®, the public gateway to the MEDLINE^® database of bibliographic records from the medical and biomedical primary literature. Unlike most previous studies on general Web search, our work examines user activities with a highly-specialized search engine. We encode user actions as string sequences and model these sequences using n-gram language models. The models are evaluated in terms of perplexity and in a sequence prediction task. They help us better understand how PubMed users search for information and provide an enabler for improving users’ search experience.     

Displacement and Supplemental Effects of the Mobile Internet on Fixed Internet Use

Mobile devices facilitate the use of mobile services that are similar to services used via fixed Internet connections. The objective of this article is to assess displacement effects between fixed and mobile Internet services, and to research the role of technical capabilities of mobile handsets and demographics as moderators. This study is based on a sample of 628 respondents who have access to fixed and mobile Internet services. The respondents' usage of services was analyzed. An online questionnaire was used to collect data on the use of information, communication, entertainment, and transaction services. Mobile Internet reinforces, rather than replaces, Internet usage. When people possess an iPhone^® or (mobile) laptop, this reinforcement effect is present for entertainment services. With respect to transaction services, the Blackberry^® makes a stronger case. With the exception of gender, demographic characteristics do not have a moderating effect. Women display a stronger reinforcement effect than men in relation to transaction services. To the best of our knowledge, no study to date has investigated the displacement effects of fixed Internet services by the mobile handset. This empirical study contributes to the literature regarding the displacement effects of mobile Internet services.     

Powdered Cellulose Poultices in Stone and Wall Painting Conservation - Myths and Realities

Abstract

Cellulose poultices are frequently used in stone and wall painting conservation for the purposes of soluble salt extraction, consolidation and cleaning. They have the reputation of being easy and pleasant to work with, have a neutral pH, high water absorption and plasticity, exhibit good conformance and adhesion to the substrate, and in most cases leave minimal residues after clearance. The cellulosic materials from which they are composed range from cotton wool, blotting paper or newspaper, to cellulose powders, the latter now by far the most common form of cellulose used today by conservators. Drawbacks of these products include poor water retention when applied to vertical surfaces, a tendency to redistribute salts further into the object substrate, and poor long-term treatment effectiveness for salt extraction. Hence cellulose poultices are used frequently due to good working properties, but apparently are in some situations not very effective. In this paper, existing knowledge of these poultices is outlined, followed by investigations undertaken to fill some of the knowledge gaps. Investigations include characterization of poultice properties such as pore size distribution and workability, and of moisture transport processes within poultice/substrate systems including moisture penetration depth, moisture distribution, and poultice shrinkage during drying. Cellulose powder products known under the trade name Arbocel^®, extensively tested and used in conservation over several decades, were a particular focus. Resulting guidelines include counter-intuitive measures such as (when used for salt extraction purposes) the use of thinner poultices to reduce drying shrinkage and salt redistribution further into the substrate. The relatively uniform pore size distribution (around 10 μm) of Arbocel^® poultices makes them more appropriate for salt extraction on substrates with a medium-coarse pore size (i.e. 15 μm and above), while on fine porous substrates (10 μm and below), the extraction will not be as efficient.     

Web-Based Citation Management Compared to EndNote: Options for Medical Sciences

ABSTRACT

The authors of this article analyzed the differences in output when searching MEDLINE direct and MEDLINE via citation management software, EndNote X1®, EndNote Web®, and RefWorks^©. Several searches were performed on Ovid MEDLINE and PubMed directly. These searches were compared against the same searches conducted in Ovid MEDLINE and PubMed using the search features in EndNote X1, EndNote Web, and RefWorks. Findings indicated that for in-depth research users, should search the databases directly rather than through the citation management software interface. The search results indicated it would be appropriate to search databases via citation management software for citation verification tasks and for cursory keyword searching.     

Durability of Chinese Repair Bamboo Papers under Artificial Aging Conditions

ABSTRACT

To study the life expectancy and difference in aging resistance properties of different modern repair bamboo papers, hydrothermal/dry-heat ageing experiments on repair bamboo paper samples were conducted. The mechanical strength (tensile strength and folding endurance) of different papers during the ageing process were analyzed. Furthermore, the chemical properties (degree of polymerization and pH) of the samples were tested to search for the immanent cause of paper ageing. The results indicated that the ageing resistance ability and durability of modern repair paper are strongly related to their production process, which corresponds with the initial properties of the paper. Mechanical pulp had a low degradation resistance, which was further exacerbated by the chemical bleaching process. In the long run, traditional handmade papers with solar bleaching processes will have longer-term stability and durability.     

Evaluation of query expansion using MeSH in PubMed

This paper investigates the effectiveness of using MeSH^® in PubMed through its automatic query expansion process: Automatic Term Mapping (ATM). We run Boolean searches based on a collection of 55 topics and about 160,000 MEDLINE^® citations used in the 2006 and 2007 TREC Genomics Tracks. For each topic, we first automatically construct a query by selecting keywords from the question. Next, each query is expanded by ATM, which assigns different search tags to terms in the query. Three search tags: [MeSH Terms], [Text Words], and [All Fields] are chosen to be studied after expansion because they all make use of the MeSH field of indexed MEDLINE citations. Furthermore, we characterize the two different mechanisms by which the MeSH field is used. Retrieval results using MeSH after expansion are compared to those solely based on the words in MEDLINE title and abstracts. The aggregate retrieval performance is assessed using both F-measure and mean rank precision. Experimental results suggest that query expansion using MeSH in PubMed can generally improve retrieval performance, but the improvement may not affect end PubMed users in realistic situations.     

Research practices of humanities scholars in an online environment: The Getty online searching project report no. 3

Use of online databases by humanities scholars searching as end users was monitored in a 2-year project conducted by the Getty Art History Information Program. Visiting Scholars at the Getty Center for the History of Art and the Humanities in Santa Monica, California, were offered the opportunity to do unlimited subsidized searching of DIALOG^® databases. This third report from the project presents results of interviews conducted with the scholars regarding their experiences with searching, the role the searching took in their broader research activities, and their attitudes about the future of online searching in the humanities. Scholars found the experience stimulating and novel, with comments ranging from its “addictive” properties to a “Sorcerer's Apprentice” quality to complaints about the “industrialization of scholarship.” Generally, the scholars saw DIALOG searching as supplementing their usual research methods, and not changing them in a fundamental way. Online searching was seen as particularly useful for interdisciplinary research, and as possibly setting a new standard for the extent of literature that should be reviewed. Identified problems were about equally divided between difficulties with the search interface and lack of desired types of resources. All foresaw online searching being used in the future by arts and humanities scholars.     

Action Mechanism of Sticky Rice-Paste-Modified Site Soil: A Traditional Chinese Cementitious Material

ABSTRACT

Sticky rice paste is a viscous material commonly used in traditional Chinese construction. It has the basic properties of high viscosity and viscoelasticity, good corrosion and weather resistance, and a small coefficient of expansion. Sticky rice paste is usually added to site soils to modify their basic physical and mechanical properties. This study found that gelatinized sticky rice-paste-modified site soils have clearly improved physical and mechanical properties compared to 20 and 100°C water-modified soils when 1% (wt%) sticky rice paste is added as the soil modifier. The liquid and plastic limits, and the plastic index of the soil are improved upon modification, to 27.4, 17.7, and 9.7%, respectively. The unconfined compressive strength and hydraulic conductivity were significantly increased and reduced, respectively. In addition, there was a reduction in the rate of disintegration by water, while the water resistance of the soil was improved. X-ray diffraction, Fourier transform infrared, and thermogravimetry/differential scanning calorimetry studies reveal that the improved properties arise through physical processes between the sticky rice paste and the soil. Scanning electron microscopy reveals that dispersed branched-chain sticky rice-paste molecules extensively infiltrate the surfaces of the soil particles on the nanoscale and become attached to them to form a good adhesive colloid that solidifies the soil particles after water evaporation, resulting in a compact structure.     

Coat of arms: Dovetailing the needs of outdoor sculpture and military assets to develop more durable and adaptable paint systems

The requirements for paints used on outdoor sculpture and military vehicles are similar: overall protection for the underlying substrate, and the ability to withstand prolonged outdoor exposure and recurring physical contact. Aesthetic requirements are different but stringent for both categories of coatings and include maintaining appearance over time. Building on prior work undertaken by the United States Department of Defense (DoD) Army Research Laboratory (ARL) to modify military coating systems into a matte black paint suitable for outdoor sculpture, a long-term interdisciplinary collaboration is under way between the ARL, the Getty Conservation Institute, Mack Art Conservation, and NCP Coatings, that aims to develop and evaluate a wider range of robust paint systems with novel attributes for both the DoD and outdoor painted sculptures. For the latter, this includes coatings with a broader range of gloss, formulated with a much more varied palette. New low-gloss coatings used on military assets were used to paint sculptures by Alexander Calder, Tony Smith, and Louise Nevelson, designed to an aesthetic standard based on approved colour and gloss levels by the relevant artists’ foundations and estates, and formulated to enhance durability. These new coatings offer the ability to match or meet a range of artists’ aesthetic preferences, and to use a variety of polymeric flattening agents to control gloss levels, reduce marring, and eliminate volatile and hazardous pollutants. The use of low molecular weight (LMW) resins provides 4–8 hour pot life to assist in the application process. Compared to current resins, the LMW systems reduce organic solvent levels, are low viscosity, and permit far easier application. In addition, the replacement of typical pigments with low solar absorbing (LSA) pigmentation provides higher reflection which ‘shields’ the resin/binder system and reduces degradation. A particular advantage to conservators from this collaboration is that the coatings on DoD assets provide a convenient indicator of the paint's performance and durability. The outcome will be a unique coating system to provide enhanced durability and maintain the original coating properties for a period of 6–10 years.