1.18 Development of a Hermetically Sealed Nitrogen Atmosphere Display Case

Lightsense Corporation
The Getty Conservation Institute

Lawrence S. Ring
Wayne E. Rodgers
Shin Maekawa
Frank Preusser
Vinod Daniel
Period of Activity: 9/88 to 2/89

Project Abstract
This project, carried out for the Egyptian Antiquities Organization designed and built a display case for the storage and/or exhibition of any organic or environmentally sensitive object(s), specifically the Royal Mummies, that included a pure nitrogen environment, relative humidity stability, ultra-low-leak design and detection, and all requisite monitoring electronics.

Primary Publications
Ring, L. S., and W. Rodgers, "Getty Hermetically Sealed Display System: Final Report-Phase 3 Completion," Final Report to the Getty Conservation Institute, March 6, 1989.

ABSTRACT-Phase 1 of this project was satisfactorily completed with a report on the design for the GHS Display System on September 16, 1988. Phase 2 of the contract ended with the delivery and installation of a full size prototype GHS case on February 6, 1989. Phase 3 of the contract covered four areas of investigation: (1) Selection and recommendations on monitoring equipment, (2) selection and recommendations on data logging equipment, (3) leak testing, and (4) cleaning resistance. This final report covers the information and tests outlined in phase 3. Also attached are copies of the construction drawings and brief assembly instructions.

Valentin, N., and F. Preusser, "Nitrogen for Biodeterioration Control in Museum Collections," Presentation at the Pan-American Biodeterioration Society, Washington, D.C., August 3-6, 1989.

ABSTRACT-The biological activity of microbes and insects under a nitrogen atmosphere was analyzed in contaminated art materials. 14C tracers were used for the evaluation of aerobic microbial activity. Membrane filtration and fluorescence microscopy techniques were applied for assessing anaerobic bacterial growth. The lethal effect of nitrogen as anoxant for the eradication of insect populations was determined at controlled oxygen levels, temperature, and relative humidity using Drosophila melanogaster as an experimental control. Significant decrease of the biological activity and microbial growth were found on contaminated samples exposed to low levels of both relative humidity and oxygen by replacing air with nitrogen in a sealed space. Indeed, nitrogen was found as an effective means for eliminating insects from art objects. An inexpensive, safe, and easily handled alternative to toxic fumigant methods is proposed.

Valentin, N., M. Lidstrom, and F. Preusser, "Microbial Control by Low Oxygen and Relative Humidity Environments," Studies in Conservation, Vol. 35, 1990, pp. 222-230.

ABSTRACT-Most fumigants used for disinfection of contaminated art collections are toxic compounds which may also damage the treated objects. To avoid these problems, an approach to control microbial activity on museum objects has been developed employing an inert gas, nitrogen, and low relative humidity. A method based on the use of 14C-labeled radioactive tracer has been applied for the evaluation of microbial growth on parchment samples selected as experimental material. This technique does not require the isolation and characterization of microorganisms involved in the decomposition processes. The method of microbial that we have investigated is safe, noninvasive, and can reduce further chemical alteration of the substrate including photooxidative processes.

Valentin, N., and F. Preusser, "Insect Control by Inert Gases on Museum Archives and Libraries," Restaurator, Vol. 11, 1990, pp. 22-23.

ABSTRACT-The lethal effect that the displacement of oxygen by an inert gas, nitrogen, produces on insect populations has been investigated using the fly, Drosophila melanogaster, as a model insect. Nitrogen was evaluated for eliminating all stages of the life cycles of Drosophila exposed to various combinations of relative humidity and temperature. Using nitrogen as anoxant, no remaining biological activity of the insect treated at control conditions was found. A simple, inexpensive, and safe alternative treatment to common fumigation systems for eliminating insect pests in ancient objects is proposed. This approach is also being studied to eradicate termites, Cryptotermes brevis, from infested wood.

Valentin, N., "Evaluation of Bacterial Contamination on Objets d'Art by Membrane Filtration and Epifluorescence Microscopy," International Biodeterioration, Vol. 26, 1990, pp. 369-379.

ABSTRACT-Bacterial contamination on proteinaceous art objects such as parchment and mummies exposed to low RH and low oxygen levels has been assessed using polycarbonate nucleopore filter and incident light (epifluorescence) microscopy. The technique described is a rapid and sensitive means for observing and evaluating bacterial populations including anaerobic organisms involved in collagen depolymerization processes. A relationship has been found between fluorescence counts and plate colony counts from contaminated seventeenth-century parchment treated by microenvironmental control and modified atmospheres.

Valentin, N., "Nitrogen Atmosphere to Control Biodeterioration of Egyptian Mummies," Nature, Vol. 338, April 6, 1989, p. 463.

ABSTRACT-None available.

Valentin, N., and F. Preusser, "Nitrogen for Biodeterioration Control on Museum Collections," Biodeterioration Research, Vol. 3, Plenum Press, New York. 1990, pp. 511- 523.

ABSTRACT-A method of microbial control and insect eradication has been developed using inert gases, nitrogen, and a low relative humidity in a hermetically sealed case. Radioactive tracers were used to assess the biological activity of fungal contaminants inoculated on new parchment samples and exposed to a nitrogen atmosphere at fixed relative humidities. Bacterial growth was evaluated by membrane filtration and epifluorescence microscopy using ancient parchment under different levels of relative humidity and oxygen. The lethal effect of nitrogen as anoxant for eliminating insect populations was determined using D. melanogaster as an experimental model. C. brevis was also studied.

Maekawa, S., F. Lambert, F. Preusser, and E. Hansen, "Hermetically Sealed Case for the Storage of Objects in a Stable, Inert Atmosphere," Storage of Natural History Collections: Ideas and Practical Solutions, eds. C. L. Rose, A. R. de Torres, Society for the Preservation of Natural History Collections, 1992, pp. 249-250.

ABSTRACT-None available.

Maekawa, S., F. Lambert, and F. D. Preusser , "A Hermetically Sealed Case for the Display and Storage of Mummified Objects in a Stable Inert Atmosphere," Presentation at the 1st International Congress on Mummy Studies, Puerto de la Cruz, Tenerife, Spain, February 3-6, 1992.

ABSTRACT-A display and storage system was designed and built by the Getty Conservation Institute for the preservation of mummified objects by statically controlling the levels of oxygen and relative humidity. The case is useful for preventing deterioration of many mummified objects in museums resulting from changes in humidity, biological attack (microorganisms and insects), thermally and photolytically induced oxidation, and attack by gaseous and particulate air pollutants. The hermetically sealed, nitrogen filled case maintains its pressure equilibrium with the surrounding atmosphere by compensating its volume with movements of a bellows. The case contains sensors for oxygen and humidity, humidity buffer, oxygen scavenger, and pollutant sorbent. Under normal conditions the case can be maintained at under 2% oxygen concentration without major maintenance for a period of up to ten years without oxygen scavenger in the case. After that period the case has to be flushed with humidity conditioned nitrogen, and the buffers and sorbents replaced.

Lambert, F. L., V. Daniel, and F. D. Preusser, "The Rate of Absorption of Oxygen by Ageless?; The Utility of an Oxygen Scavenger in Sealed Cases," Studies in Conservation, Vol. 37, Nš 4, 1992, pp. 267-274.

ABSTRACT-The kinetics of the reaction of Ageless? with oxygen were studied and an expression was obtained for the rate of oxygen reaction with Ageless: an empirical first order rate equation which involves the chamber volume and the Ageless capacity as well as the concentration of oxygen. Two factors, which decrease the rate of reaction, low relative humidity and restricted access of oxygen to the Ageless packets, were evaluated. The usefulness of an oxygen scavenger such as Ageless in prolonging the life span of an oxygen-free atmosphere in a museum case is discussed.

"Deterring Deterioration... Developing a Case for the Control of the Environment," Technology and Conservation, Vol. 12, Nš 1, 1994, pp. 10, 12-13. ABSTRACT-The history and development of the hermetically sealed prototype case is described.