Friends - I recall many years ago, when ethylene oxide was in vogue, the Italians reported fumigated articles were more prone to fungal development after fumigation than before. Perhaps someone is confusing the nitrogen/argon thing with the old reports generated when ethylene oxide was the "fumigant of choice."
Having worked with all sorts of institutions operating anoxic chambers, there are pros and cons to each gas - nitrogen vs. argon. If someone is using a "large bag system", introduction of the heavier-than-air argon into the bottom will force all the interior air out of the top. The top vent is then sealed. In fact, several individuals simply use large, polyethylene trash cans, which are outfitted with an inlet fitting on the bottom outside edge and a release valve in the top center of the lid. The lid is taped onto the trash can, the valve at the top is opened, the argon is introduced at the bottom, and in short order, the top valve is then closed, resulting in a trash can full of pure argon. Doesn't get much simpler than that. Thomas A. Parker, PhD -----Original Message----- From: Kate Payne <avikate...@yahoo.com> To: pestlist@museumpests.net Sent: Wed, Oct 13, 2010 3:49 pm Subject: Re: [pestlist] Fwd: Fumigating cabinets - bug infestation Thanks for sharing your thoughts, all, this has gotten quite interesting. I think for some of us who have our own set-ups going, we've found that companies who will rent cylinders of nitrogen and/or argon at the purity required for anoxic treatments generally charge more for argon cylinder rentals ($10-$20 more per cylinder, if I'm remembering correctly). It would be fascinating to know more (from a mycologist's perspective) about fungal issues nitrogen vs. argon, but it would seem in practice that high humidity with the right amount of warmth seem to be greater factors in terms of fungal spores developing into a full fledged fungal infestation. I think it's important to find a common ground to provide information and access to pest eradication methods for conservation professionals everywhere. Some will find it more feasible to work with nitrogen, some with argon, some with carbon dioxide, and some on a small scale might find it best to work with oxygen scavengers. Rather than watch the discussion devolve into a competition between commercial providers, perhaps we'd best look to publications like this: Inert Gases in the Control of Museum Insect Pests http://www.getty.edu/conservation/publications/pdf_publications/inertgases.pdf and realize that there are merits in each of the different methods and plenty of room for research and growth. I've also attached the research article that Steve Pine referenced, just in case anyone was unable to access the .pdf online. With a bit of ingenuity, anyone can create an anoxic treatment set-up. Additionally there are temperature methods (as mentioned in a previous comment to this thread), and each conservation professional can do a bit of research and assess what is right for their particular situation. Happy bug-killing! Cheers! Kate Payne de Chavez From: "wlou...@aol.com" <wlou...@aol.com> To: pestlist@museumpests.net Sent: Wed, October 13, 2010 2:45:21 PM Subject: Re: R: Re: [pestlist] Fwd: Fumigating cabinets - bug infestation Argon is a by product of collecting nitrogen, no extra cost involved. Yes, nitrogen is used most often based on cost and easier to contain in a chamber. Nitrogen does not penetrate as well as argon, look at your periodic table for weights. Use your FTIR to test argon verses nitrogen on real Art objects. You will be surprised. Nitrogen chambers just like yours were being made by Rentokil long before you were involved 10 years ago. Nitrogen was used during the Second World War to kill insects and rodents in food sources. There are some references dating to 1890's in Australia using nitrogen for insects. It was a by product in ice making then. Rentokil followed Bob Koestler lectures before creating their nitrogen generator system. Look back at the research papers in the mid 1980's early 1990's full of information in the beginning years I have been working with anoxic chambers for 20+ years some of those years in a Conservation department at a major museum. Why is the United State Constitution the most important document in our history stored under argon not nitrogen gas? Do your research learn about the differences between argon and nitrogen its an interesting trip. I have about 5 years into the comparison still learning. Bill Art Care International In a message dated 10/13/2010 10:53:23 A.M. Eastern Daylight Time, rgi...@tiscali.it writes: The letter of Stephan Schaefer is simply perfect.... I have been the coordinator of the SAVE ART project of European Union and our team (Italy, Spain, Sweden and UK) has certified the anoxia method (Nitrogen) to eradicate insect pests carried ot by VELOXY equipment (VEry Low OXY). It was almost ten years ago and until now I never heard about microrganisms problems.... This is a matter of humidity. There is no difference among Argon and N2 to kill pests but there is a great difference in costs. Moreover, to separate Argon from air implies a great consumption of energy and to produce energy means pollution of environment. Ercole Gialdi (rgi...@tiscali.it) ----Messaggio originale---- Da: step...@stephan-schaefer.com Data: 13/10/2010 15.44 A: <pestlist@museumpests.net> Ogg: Re: [pestlist] Fwd: Fumigating cabinets - bug infestation Re: Choice of Argon vs. Nitrogen for the treatment and control of insect infestation In reference to the questionable statement, that "inert" gases other than argon "are likely to foster fungal growth" I think it is important to clarify some issues regarding the use of either gas for the control of insect pests and the influence on microbiological activity. First of all, both gases are entirely inert and scientific research has proven their full efficacy in eliminating all types of insect pests in all life stages (given that specific conditions are being maintained and controlled during treatment). Second, fungal germination and growth depends upon the substrate and ambient conditions. Actually, most of us will intuitively know that fungal and bacterial development only occurs at higher humidity levels and where there is lack of ventilation. Actually, the threshold level lies somewhere around 70% relative humidity. Below about 65% there is literally no risk for fungal and bacterial proliferation. My third and probably most important point is why nitrogen anoxia will "foster" fungal growth although it is known to be a strong inhibitor of microbiological activity?? From scientific research we only know, that some anaerobic microorganisms are able to survive under "nitrogen anoxia" conditions. The other more practical consideration is that during anoxia treatments, the humidity inside the "bubble" should always be controlled and certainly kept below 65% RH, so the likelihood of fungal growth inside the bubble under anoxic conditions is absolutely zero, whether nitrogen or argon is used. Furthermore, we are only speaking about a treatment period of approximately 30 days, the time needed to kill all insects in all developmental stages. Therefore, I think the issues of fungal growth are much more related to the environment and ambient conditions where the objects in question are being kept at all times, rather than the short period inside a bubble where they remain during an anoxic treatment and where conditions should be controlled anyway. In own experiments, where I sealed wet paper and books in gas barrier bags with Ageless oxygen absorbers, where the remaining gas is mainly nitrogen, no fungal growth was noticeable after about 50 days. The bags were kept at about 20 - 22 °C and the control that was sealed with atmospheric air inside has shown noticeable fungal and probably bacterial growth after about 72 hours. This in itself proves that fungal growth is not an issue with respect to the choice of the gas (argon or nitrogen) when considering anoxia treatment in order to eliminate insect pests. Additionally, it may be interesting to consider cost, as argon is a lot more expensive than nitrogen which is the most abundant gas in our atmosphere. I would be very interested in hearing other peoples comments on the subject. Stephan Schäfer -------------------------------------------------------- STEPHAN SCHÄFER Conservação e Restauração ltda. Rua Manduri, 400 - Jd. Paulistano 01457-020 São Paulo, Brazil Tel./Fax: 00 xx 11 3816-0489 Cel: 00 xx 11 8366-0230 e-mail: <mailto:step...@stephan-schaefer. com>step...@stephan-schaefer.com --------------------------------------------------------- --------------------------------------------------------- Prof. Dipl. Rest. Stephan Schäfer Universidade Nova de Lisboa (UNL) Faculdade de Ciências e Tecnologia (FCT) Departamento de Conservação & Restauro 2829- 516 Caparica - Lisboa PORTUGAL e-mail: <mailto:sc...@fct.unl. pt>sc...@fct.unl.pt ------------------ Supera i limiti: raddoppia la velocità da 10 a 20 Mega! Risparmia con Tutto Incluso: telefono + adsl 20 mega a soli 26,60 € al mese per un anno! SCONTO DI 160 EURO! http://abbonati.tiscali.it/telefono-adsl/prodotti/tc/tuttoincluso/?WT.mc_id=01fw
