Climatically Induced Degradation Processes in Conserved Archaeological Wood Studied by Time-lapse Photography

ABSTRACT

Samples of conserved archaeological wood of different ages, origins, and conservation histories were aged in a climate chamber for seven months, while the humidity alternated between 30% RH for 12 hours and 80% RH for 12 hours at a constant temperature of 30°C. Photographs were taken once every hour, which enabled the creation of a time-lapse movie. Some samples degraded visibly, whereas others were unaffected. Most of the samples were robust and would be able to survive well even in a very poor museum climate. Among the sensitive samples, three types of degradation were identified, namely disintegration, pyrite oxidation, and efflorescence of white crystals. Disintegration was ascribed to dimensional changes caused by the RH alternations in very fragile wood. The white efflorescence was interpreted as the recrystallization of an alum-associated substance, possibly mercallite (KHSO₄). The pyrite oxidation was observed as the efflorescence of a thick yellow, grey, and green powder. Characterization of selected samples was performed using X-ray fluorescence spectrometry, X-ray diffraction spectrometry, scanning electron microscopy with energy dispersive X-ray spectroscopy, inductively coupled plasma – optical emission spectroscopy, Fourier transform infrared spectroscopy, ionic conductivity – liquid chromatography, and pyrolysis-gas chromatography-mass spectrometry with in situ silylation using hexamethyldisilazane.     

A New Methodology for the Characterisation of Natural Dyes on Museum Objects Using Gas Chromatography–Mass Spectrometry

The derivatising agent m-(trifluoromethyl)phenyltrimethylammonium hydroxide (TMTFTH) has been employed for more than a decade at the Canadian Conservation Institute (CCI) to extract natural dyes from historical textiles and other dyed substrates. The alkaline reagent breaks the bonds between the colourants and the mordant ions or functional groups of the substrate, releasing the dye compounds into the extraction solution, and derivatises polar functionalities to produce compounds that are amenable to subsequent analysis by gas chromatography–mass spectrometry (GC–MS). This approach allows for the identification of the colourants, and is also useful in determining the presence of degradation products from the dyes and substrates, non-dye marker compounds, auxiliary compounds added to the dye bath, and substances present on the object through anthropogenic use, conservation treatments, or possible pesticide contamination. This paper discusses compounds formed through the reactions of TMTFTH with flavonoid dyes (dyer’s buckthorn, old fustic, weld, red sandalwood, and brazilwood), quinone dyes (madder, Relbunium, Galium, cochineal, lac, and walnut), indigoid dyes (indigo, Tyrian purple, and indigo carmine), turmeric, marigold, lupin and several lichen species. Results from a selection of historical dyed textiles and other decorative objects analysed at the CCI are provided to illustrate applications of the methodology.     

“I thought I’d have more trouble with white people!”: Exploring racial microaggressions between West African immigrants and African Americans

Racial tensions continue in 21st-century United States through the communication of racial microaggressions. We are interested in the communication of racial microaggressions directed towards West African immigrants by people with whom they expected to be allied, African Americans. Sixteen people who identified as West African immigrants were interviewed about communication struggles with African Americans in this qualitative, interpretive analysis. Owen’s thematic analysis was employed to analyze interview data. Results suggest the communicative impact of racial microaggressions on recipients is far-reaching and consequential. Narratives illustrate microaggressive communication occurs daily through invalidating, dismissive lines of questioning as well as targeted name calling and pejorative dialogue.     

Two Stangengläser from the collection of the Museum of Decorative Arts in Prague: Decorative techniques,material analyses,and conservation

Abstract

The two Stangengläser, tall cylindrical vessels from the beginning of the seventeenth century, are described in detail. The severely damaged Stangengläser, decorated with diamond-point engraving and cold-painting, were challenging to treat. Research preceding the conservation revealed differences in decorating techniques. Samples of the paint layers were analyzed using micro-Fourier transform infrared spectroscopy. Two layers of resinous varnish with a middle layer of paint containing a plant gum were found on the Stangenglas with Allegory of Caritas and Zierotin coat of arms. In the plain paint layer of the Stangenglas with dancing couples, egg white was identified as the binder. The glasses, analyzed using scanning electron microscopy with energy dispersive X-ray spectrometry, had similar potash–lime–silica compositions, which seems to be characteristic for glass from Bohemian lands. Results of analysis contributed to the discussion about the possible provenance of the Stangengläser, the glassworks at Wilhelmberg, South Bohemia.     

Evaluation of sodium nitrite as a corrosion inhibitor for USS Monitor artifacts

Abstract

The use of sodium nitrite (NaNO₂) as a corrosion inhibitor for wet archeological metal objects presents potential advantages of near neutral pH, low concentration, effectiveness on several metals, and compatibility with organic materials. The effectiveness of NaNO₂ as a corrosion inhibitor for storage of chloride-containing marine archeological metal objects from the wreck of the USS Monitor was evaluated using marine-corroded carbon steel analogs. The samples were tested in varying concentrations of NaNO₂ and evaluated visually and by monitoring solution chemistry using ion chromatography (IC). It was found that a concentration of 1000 ppm NaNO₂, replaced four times, was effective at protecting corroded carbon steel in the presence of chlorides. Nitrite solutions were no more rapid than sodium hydroxide (NaOH) at extracting chlorides from marine steel at equal concentrations and were considerably slower than 2% NaOH. IC analyses indicated that NO₂ does not easily oxidize to NO₃ under normal conditions, but does so readily when a polarizing current is applied, making nitrites unsuitable for electrolytic reduction treatments. Sodium nitrite does show promise as a storage solution prior to desalination of marine metals or after desalination to prevent flash corrosion during rinsing baths.     

Pickeringite: A deleterious salt on buildings

Pickeringite, MgAl₂(SO₄)₄·22H₂O, was observed as efflorescence at the church of Saints Peter and Paul in Largario (Switzerland). The spongy salt crusts formed directly on rusty, deeply weathered gneiss rich in mica. The building stones originate from rocks in the vicinity of the village. On outcrops, similar occurrences were discovered. Ferrous and pyritic gneiss exhibited efflorescences of gypsum, epsomite, potassium alum, and pickeringite in sheltered places. Based on these observations and the known conditions of formation, we conclude that pickeringite resulted as a secondary mineral from weathering of pyritic gneiss. Most likely, weathering happened in an environment where, among other ions, aluminium and magnesium were present, but calcium and carbonate were absent. Such conditions rarely occur. If our hypothesis was confirmed, the fact that an extremely acid, calcium- and carbonate-free weathering system evolves next to lime mortars and plasters would be very surprising. It would imply that restricted zones devoid of a buffering effect develop on a microscopic scale.     

Study of the deterioration products,gilding, and polychromy of the stones of the Scuola Grande Di San Marco's façade in Venice

The Scuola Grande di San Marco is one of the most outstanding Renaissance buildings in Venice. Destroyed by fire in 1485, the Scuola was reconstructed between 1487 and 1495 by Pietro Lombardi (and sons), together with Giovanni Buora and Mauro Codussi. The façade is considered one of the finest and most original exteriors of Venetian buildings and in particular features refined sculptural and painted decorations and a remarkable pictorial effect created by the extensive use of polychrome marbles and the false perspective view between the pilasters of the lower order. Most of the stone materials (Istrian and Verona red limestones, nero di Roveré, pavonazzetto toscano, Carrara marble and various reused antique marbles) present evident decay phenomena such as scaling, exfoliation, powdering, fissuring, salt efflorescence, black crusts, and artificial patinas of various kinds. The present study reports the results of petrographic and chemical laboratory analyses carried out in preparation for the conservation treatment of the building, in order to characterize the main micro- and macro-morphologies of decay and to identify the causes and mechanisms of deterioration as well as the nature and application technique of the polychromy, gilding, and patinas present on parts of the monumental Renaissance façade.     

Laser Sensors for Continuous In-Situ Monitoring of the Dimensional Response of Wooden Objects

Abstract

The application of triangulation laser displacement sensors to the continuous in-situ monitoring of the response of wooden cultural objects to variations in temperature and relative humidity in their environment is reported. The sensors are robust, fast and precise, provide non-contact measurements, and are capable of operating in the field. They have been applied to monitor the response of the altarpiece in the church of Santa Maria Maddalena in Rocca Pietore, Italy, to fluctuations in temperature and relative humidity caused by the use of the heating system. Complex short-, medium- and long-term responses of a variety of carved wooden elements have been recorded.     

Race,whiteness, "lightness," and relevance: African American and European American interpretations of Jump Start and The Boondocks

African American and European American participants were interviewed about two syndicated comic strips written by and featuring African Americans: Jump Start, a comic strip that portrays African Americans in a normative middle-class family narrative and focuses only occasionally on racial issues, and The Boondocks, a comic strip that focuses frequently on racial issues. The African American groups interpreted the comic strips through the terministic screen of race cognizance, through which racial politics and oppression were highly relevant. Almost all of the European American participants, however, interpreted the comic strips through the terministic screen of Whiteness, through which racial politics and oppression were not relevant.     

WATERLOGGED WOOD PRESERVATION WITH POLYETHYLENE GLYCOL

Abstract

Polyethylene glycol 1540 was tested in the preservation of a waterlogged, carved, and painted wooden bowl from a prehistoric site on Patarata Island, Veracruz, Mexico. The procedure successfully employed water and Carbowax 1540 in a partial substitution process.     

Material properties of historic parchment: A reference collection survey

Historic parchment is a complex biological material, and due to various methods of production or inks used, unknown environmental histories of objects and heterogeneous nature of animal skin, it represents a particular analytical challenge. Due to the number of variables it is likely that patterns in degradation of these historic objects can only be revealed by surveying the material properties of a significant number of real objects. In this work, a sacrificial collection of ca. 100 historic parchments (fifteenth to twentieth century) was characterized using a range of techniques available to conservation practitioners that can usefully be used to reliably and rapidly characterize parchment. We focused on micro-destructive methods, such as shrinkage temperature (T_s), as the most widely used indicator of parchment degradation. Lipid content, roughness, and ink pH were additionally measured, while a limited number of samples containing iron gall ink were also examined using scanning electron microscopy (SEM) and SEM-EDX, to explore the distribution of ink components. Even in the absence of detailed environmental histories, it is possible to acknowledge the significance of the effect of iron gall ink and its acidity, and of lipids on parchment degradation, as measured using T_s. This research reports valuable reference data, while the collection remains accessible for further research.     

FTIR Measurement of Cellulose Microfibril Angle in Historic Scots Pine Wood and Its Use to Detect Fungal Decay

Microfibril angle (MFA) – the orientation of cellulose fibres in the S2 layer of the secondary cell wall – is a key determinant of the stiffness and strength of timber. The microfibril angle depends on the way in which the timber was grown and its position within the tree. Microfibril angle can be measured by X-ray diffraction and other methods, but the methods in current use are slow or require advanced instrumentation. The aim of this study was to explore the use of polarised Fourier transform infrared (FTIR) microscopy as a relatively fast and inexpensive method for measuring MFA in historic Scots pine (Pinus sylvestris L.). The FTIR measurements were calibrated against X-ray measurements of MFA in modern Scots pine. We observed a wide range in MFA values and a radial pattern of MFA similar to modern Scots pine in undecayed Scots pine heartwood from sixteenth and seventeenth century beams in Scottish secular buildings. The density of the heartwood was also similar to modern plantation-grown Scots pine despite the much slower growth rate recorded in the ring widths of the historic timber. The sapwood, which had been attacked by both insect pests and fungi, showed an erratic reduction in density and a large increase in MFA compared to the modern material. The increased sapwood MFA was attributed to selective destruction of the S2 layer of the wood cell walls by fungal decay. Using MFA measurements in conjunction with density offers the possibility to estimate the mechanical properties of sound historic pine timber, to detect fungal decay more sensitively than by density alone, and to distinguish between pest and fungal attack in a way that relates directly to the remaining mechanical performance of the timber.     

Risk Assessment and Preservative Measures for Volatile Organic Compounds in Museum Showcases

ABSTRACT

The first step in preservative measures for artworks in airtight showcases is the exclusion of outgassing from construction materials or, at least, limitation of the emissions to a minimum acceptable level if the volatile organic compounds (VOCs) generated may be qualified as harmless. Once it is ascertained that the objects in the showcases are responsible for VOC emissions, a step forward becomes necessary, implying showcase ventilation with air flowing through active sorbent materials. Solid phase micro-extraction (SPME) followed by GC separation and MS identification has been applied for checking the outgassing characteristics of different types of materials used for the construction of airtight showcases, and the method was found particularly attractive in terms of speed and sensitivity, suitable for measurements in presence of low-emitting materials. Sampling could also be done in the case interiors, thus making possible detection and recognition of emissions from art objects within a case. A comprehensive preventive conservation scheme has been further devised by means of active air circulation within the showcase and functional sorbent materials along the flow, for complete suppression of gaseous compounds. Control of the compounds in the air flow and of their filtration efficacy was achieved by direct sampling, also using SPME fibers. Continuous monitoring of the air quality in the showcases has been developed with insertion of a photoionization detector capable of detecting the VOCs in the air by inducing molecular ionization, and measuring the generated photocurrent. The system is not selective, but gives the total concentration, reaching ppb sensitivity with high-quality data. In addition it includes temperature and humidity sensors, making the whole a useful instrument for environment control.     

Reading African Women's Writing: The Role of Librarians in Expanding the Canon

SUMMARY

This paper will briefly review the canon debate in African literature, situating it within a wider context of debates on other non-Western, non-central or emerging disciplines. It will then examine ways in which reference services can respond to the challenge of canon expansion, and how librarians can impact the study of African women writers in universities and colleges. I will approach these topics from two perspectives. The first involves reference librarians in their traditional role as information mediators. Using the works of female writers as examples in instruction sessions and reference guides are ways in which traditional methods can be given a new twist. In so doing, reference librarians will be combining intercultural literacy with information literacy. A bibliography of selected works will also be given that will help general reference librarians strengthen their collections and educate themselves on the subject.

The second will be on ways in which librarians can add a layer to traditional mediating by becoming academic activists. In other words, instead of passively waiting for courses to be created and then supporting them, librarians can market to faculty ideas for possible uses of the Africana collection and thus provide impetus for new course development. Suggested initiatives include developing theme-related guides or readers' advisory based on African women's texts, and distributing them to other Area Studies faculty–an obvious way to encourage comparative, interdisciplinary research and teaching. Librarians can also hold workshops to demonstrate how works such as Aidoo's Changes or Dangaremgba's Nervous Conditions that examine the many faces of modern Africa can be discussed in social history, politics or education courses; or Alifa Rifaat's works dealing with women in Islamic communities in a religion or comparative law course. Additionally, libraries need to go beyond in-house, library-only lectures to organizing, for example, campus-wide author lecture series.

To effectively implement these initiatives, reference librarians should collaborate more closely with Africana and Area Studies bibliographers. As librarians in the 21st century, we should be more proactive in our academic communities. We can generate impetus for breaking the literary canon and broadening literary research, foster greater understanding of African culture, while still playing our time-honored roles of guide, mediator, culture-keeper, and agents of change.     

Hydrogen plasma reactions in a d.c. mode for the conservation of iron meteorites and antiquities

Abstract

Four iron meteorite fragments and 13 archaeological iron objects were exposed to a lowpressure hydrogen plasma for up to two weeks in a pilot apparatus. In the experiment the objects acted as cathodes in a 600–1600V d.c. electrical field. While the chlorine-containing β-FeOOH, akaganeite, was present in all objects before the test, no akaganeite and no chlorides were present afterwards. The objects, including one meteorite which had been exposed for more than 5000 years to seawater, were found to be stable after the glow discharge treatment. The major mineral after treatment was identified as magnetite, and the objects generally assumed an iron-grey surface colour. No sputtering and no reduction to free iron took place under the test conditions, operating at or below 120°C and at pressures of O·4–1mb hydrogen.     

Biological Pest Control of a Biscuit Beetle (Stegobium paniceum) Infestation in an Old Masters Paintings Storage Area

ABSTRACT

We report on biological control of an active infestation by biscuit beetles (Stegobium paniceum) of museum objects (Old Masters paintings) in the storage facilities of the Museum of Fine Arts in Vienna. Because chemical and non-chemical treatment methods would have been very problematic, the release of parasitic wasps (Lariophagus distinguendus) was discussed and accepted by the director of the collection. We released 3000 wasps every month from August 2013 until September 2014 in the two infested storage rooms and monitored the activity of biscuit beetles on sticky blunder traps and light traps, and also by visual inspection. In the insect monitoring of 2014 until 2018 no more biscuit beetles were found in the two storage depositories, showing that the treatment was 100% successful. To our knowledge, this is the first proof of a fully successful biological control of a museum pest using parasitoids only, and also of stored product/food pest, outside a laboratory experimental setup. This biological pest control method allowed avoiding negative side effects such as contamination from treatments with biocides, or costly logistics in case of chemical-free methods.     

Hall of Mirrors: The Dilemmas of Presenting Information Technology Culture Through Information Technology Interactives and Artifacts

This paper examines how the problem of exhibiting computing artifacts was confronted by the development team of the Powerhouse Museum's new computing exhibition: Universal Machine. Universal Machine uses a mix of objects, activity trails and computer-based audiovisual and interactive technologies to take visitors on a journey through the origins, meaning and impact of contemporary information technology. It explores the interpretive partnerships developed between objects, new and traditional media, as well as the ways in which experience-based and multiple intelligence education theory informed design and content development.     

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.

     

Microwave Treatment for Pest Control: Coleoptera Insects in Wooden Objects

By far the most common species of woodworms perceived to be the main cause of damage to wood, and in particular to wooden art objects, are Anobium punctatum de Geer and Hylotrupes bajulas of Coleoptera family. In search of non-chemical methods for eradicating these wood pests, microwave (MW) heating can be an effective tool to help control the insects in their different life stages (eggs, larvae, and adult). The effect of 2.45?GHz frequency MW exposure on wooden art objects is described and discussed. MW heating time is reported in connection with lethal temperature of the pest and moisture content of the treated wooden object. The treatment was carried out using Microwood 12, especially conceived for portability, easy operation, and control. Microwood 12 consists of a switch mode high-voltage power supply and an industrial continuous wave magnetron connected to a rectangular-shaped horn antenna. The measure of temperature and control of operation is done via a built-in infrared thermometer.