Shin Maekawa

Microbial control in archives, libraries and museums by ventilation systems

Many archive, library and museum in hot and humid regions of the world constitute microenvironments in the building that are conducive to the growth of micro-organisms, on their collections. Conservators have often dealt with the problem through an extensive disinfection and cleaning of the collections which use harsh and toxic chemicals. Consequently, it became necessary to search for a safe, effective and locally sustainable solution for the problem. It is commonly considered that high relative humidity environments are the main factor for activity of micro-organisms on collections. However, ventilation has been proved to moderate the biodeterioration even when the objects contained high enough moisture for microbial activity. In the present work the efficacy of ventilation to arrest microbial growth and reduce activity in both contaminated air and historic objects has been investigated. Laboratory experiments were carried out using a 500-liter environmental chamber to simulate contaminated rooms in buildings. Specific ventilation requirements to control fungal and bacterial activities in the air and paper samples have been established. These constitute a safe, reliable, and low cost control method for fungal and bacterial contamination of historic objects. In addition, ventilation is an appropriate alternative to air conditioning for those buildings located in humid region. Most importantly, it avoids the use of chemical disinfecting treatments.

Large-scale assessment of light-induced color change in air and anoxic environments

Abstract A wide-ranging sample set consisting of dry pigments, dyed textiles, organic and aniline-based dyes, gouaches and watercolors, fluorescent inks, and natural history specimens was exposed to light in air (20.9% oxygen) and near-anoxic environments. After a light dosage of approximately 17.5 Mlux-hours under controlled temperature and humidity conditions, 113 of 125 samples (90% of the sample set) were shown to exhibit less color change in a low-oxygen environment compared with its behavior in air. Thirty-nine percent of this subset displayed color change in anoxia that was between two and four times lower than that observed in air, whereas 47% showed color change in anoxia reduced by a factor of four or more. In contrast, six samples exhibited greater color change in anoxia than in air – these samples included Prussian blue watercolor (three samples), Antwerp blue watercolor, Verdigris dry pigment, and Fluorescent Yellow Winsor & Newton Gouache. Although the results from this small sample subset may cause concern when considering the use of anoxia in the conservation of cultural heritage, particularly for colorant systems whose behavior in anoxia has not yet been identified, this study demonstrates the overwhelming benefits of anoxic light exposure for the vast majority of samples investigated here.

Environmental Monitoring at Tiwanaku

Tiwanaku is considered to be the most highly valued archaeological site in Bolivia, and one of the most significant in the New World. The aggressive environment at Tiwanaku is thought to have damaging effects on the stability of its stone architecture and monuments. In an effort to determine the nature of this impact, The Getty Conservation Institute (GCI) collaborated with the Bolivian National Institute of Archaeology (INAR) to establish a body of environmental data on the conditions found on site. The objective of this data collection was to provide INAR with substantive information that would be of assistance as they proceed with plans to conserve and protect the monuments of Tiwanaku for the future. An environmental monitoring station was installed at the Tiwanaku site by the GCI and the INAR to collect information for two years about the climatological effects with the highest potential for damaging the monuments: solar radiation, wind, air temperature, relative humidity, ground soil temperature, stone temperature, and precipitation. This report presents the basis for and results of the data collection for aiding conservators at Tiwanaku.

Evaluation of the performance of a lightweight modular site shelter: Quantitative meteorological data and protective indices for the ‘hexashelter’

AbstractIn 1989, a temporary shelter was constructed to protect two mosaics in Cyprus. The structure was a prototype designed to cover certain categories of archaeological site. The concept behind the shelter was that it be lightweight, modular, easy to erect, relatively inexpensive compared with a conventional structure, and temporary if desired. The framework of the basic module has a zigzag profile and six sides: hence the name ‘hexashelter’. The hexagonal ‘footprint’ allows easy addition of modules by building laterally from anyone, or more, of the sides. It can also be built over somewhat irregular topography, and minimizes impact to the surface and to subsurface archaeology by using surface concrete anchor blocks as footings. The framework is aluminium tubing, covered with a fabric roof and with open-knit textile side panels. In 1991 essentially the same shelter was built at Fort Selden in New Mexico. The purpose of the second shelter was to evaluate its effectiveness. Quantitative data for the shel...

Strategies for sustainable tourism at the Mogao Grottoes of Dunhuang, China

Chapter 1: Introduction.- Chapter 2: Conceptual frameworks for managing visitor impact.- Chapter 3: The Mogao Grottoes of Dunhuang.- Chapter 4: The Mogao Visitor Study.- Chapter 5: Strategies for sustainable tourism.- Conclusions.

Chaco Canyon reburial programme

Abstract Chaco Culture National Historical Park in northwestern New Mexico contains a wealth of archaeological resources, including 150 large earth and masonry structures under active management and preservation. In response to loss of original fabric from exposure over the last 100 years and more, as well as from continuous cycles of maintenance and repair, an extensive and long-term reburial programme was embarked upon in the late 1980s. The overall context of the site and the decision to undertake reburial as a principal conservation strategy is described in Part I of this paper. Part II provides a summary of the results of partial reburial at Chetro Ked, one of the ‘great houses’ of the canyon, in which protection of original timber was the main objective. Most of the wood at Chetro Ked could be covered only by a shallow overburden of soil, necessitating a specialized reburial design and materials to exclude moisture. Recent evaluation of the efficacy of the wood reburial was undertaken. Problems and shortcomings that were identified have led to re-design of part of the reburial and more careful attention to quality control during the intervention, as well as to selection of more appropriate geosynthetic materials. Additional monitoring techniques have been developed to allow direct withdrawal of samples of wood for assessment of deterioration.

Monitoring of soil moisture in backfilled soil for conservation of an Ancestral Pueblo an great house in Chaco Canyon

Abstract An automated monitoring station, with climate sensors and a three-dimensional array of soil moisture sensors, was installed to document moisture-content changes in backfilled soil covering an Ancestral Pueblo an ‘great house’ at Chaco Culture National Historic Park, New Mexico, USA. The objective was to evaluate the performance of a geomembrane installation in the soil. Prior to its installation of the geomembrane, we observed that precipitation in winter and spring penetrated only 60–90cm into the fill during the first year after backfilling. A significant amount of moisture evaporated from the surface during the summer months, consequently the driest region was at the surface. In the following twenty-four months we observed continued dissipation of the trapped moisture towards the surface. The installation of the geomembrane system during the second year maintained a stable and dry soil environment, indicating effective surface removal of precipitation and preventing moisture penetration deeper into the soil.

Hygrometric Half-lives of Museum Cases

The moisture-buffering capability of four types of museum cases, Solander boxes, portfolio boxes, archival document cases and music boxes, was evaluated. An expression for hygrometric half-life was derived and the half-lives were compared with high, as well as low ambient relative humidity for the four types of cases in terms of their materials of construction and closure characteristics

The Moisture Buffering Capability of Museum Cases

Hygrometric half-lives and air exchange rates of four commonly used types of museum cases: Solander boxes, portfolio boxes, music boxes, and document boxes were measured. This paper will present the experimental results and illustrate the effect of the construction materials and closure characteristics on the moisture buffering capability of museum cases.

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.