Subject: Humidifying nitrogen for anoxic treatment
I'm currently evaluating the need to humidify the nitrogen flush in a nondynamic Ageless fumigation of a Japanese folding screen. Each screen panel consists of paper applied over a cedar latticework core, with the panels attached to each other by means of paper hinges. In the GCI publication Inert Gases in the Control of Museum Insect Pests (1998), Nieves Valentin's research regarding humidification of argon, carbon dioxide, and nitrogen is summarized, with the conclusion that, "...museum holdings maintained in modest relative humidity ranges can be easily disinfested using a nonhumidified inert gas. However, works of art already exposed to high humidities, and sensitive objects such as musical instruments or polychromed wood, should be treated with humidified gas." The same GCI publication refers to anoxia treatments of Japanese screens at the Los Angeles County Museum of Art in which conditioned silica gel (50%) was used to control moisture. In discussing moisture balance during nitrogen fumigation in Museum Pest Management Seminar Notes (CCI, 1993, rev. 1996), Tom Strang notes that, "organic objects contain sufficient reserves to safely equilibrate limited volumes of air... These objects will only be stressed when their buffering capacity is exceeded by too large a volume of gas or multiple exchanges of gas." Strang suggests that if one is concerned about moisture balance, two streams of nitrogen may be run at similar flow rates, with one stream being run through a water bubbler to provide an approximate 50% RH when recombined with the dry stream. While the pouch used for the fumigation of the Japanese screen can be made to fit rather closely, the volume of gas contained in the voids within the latticework will increase the overall volume of gas within the enclosure. To humidify or not to humidify, that is the question? Any thoughts on this from the prevailing fonts of modified atmosphere fumigation knowledge? Will Jeffers Collections Care Specialist Department of Scientific Research Museum of Fine Arts, Boston *** Conservation DistList Instance 13:38 Distributed: Wednesday, January 5, 2000 Message Id: cdl-13-38-015 ***Received on Tuesday, 4 January, 2000