This discussion was an area that I had not researched myself, and I was interested to see what types of pest treatments were being practiced. Five professional conservators shared their different techniques when carrying out an anoxic treatment. After the discussion of the different techniques, a comparison was compiled together about the different treatments.
Rachael Perkins Arenstein from A.M. Art Conservation, LLC discussed this type of treatment being used on-site or at home. This type of anoxic treatment uses oxygen scavengers in a completely enclosed chamber to modify the atmosphere to almost entirely of nitrogen. Keeping the oxygen levels below 0.5% for an extended amount of time will eliminate the insects within the enclosure. The object being treated was placed within the barrier film and vacuumed sealed with the oxygen scavenger packets inside. A monitor to read the oxygen levels as well as the RH/temperature was placed inside the chamber. A small window can be cut to allow the viewing of the monitors. Examples of the type of barrier film used were MarvelSeal 360 or MarvelSeal 470, and for the oxygen scavenger packets, Ageless® Z1000 were used for the treatment discussed. The amount of time to keep the object within the chamber depends on the insect, and the amount of oxygen scavenger packets depends on the size of the chamber. Another system called AnoxiBug® also deals with enclosing the object with scavenger packs within a vacuumed sealed chamber. These ready-made chambers are offered in different sizes depending on the type of the object being treated. This chamber should also have an oxygen monitor inside and a window to view during treatment.
William Donnelly from the Winterthur Museum, Garden and Library explained the modified atmosphere CO2 treatment within their collection. This type of treatment was carried out in a fixed location where the object was brought to the chamber. The CO2 canisters were attached to the framed enclosure by a hose hookup, as well as an oxygen sensor, gas monitor, vacuum pump, internal data logger, and a computer system to collect the data during the procedure. The CO2 concentration was maintained above 60% and completed on a 21-day cycle. The RH does dip with the introduction of CO2 in the atmosphere inside the chamber. This treatment is carried out on all the textiles coming into the collection.
Julie Wolfe from the Getty Conservation Institute at the J. Paul Getty Museum discussed the nitrogen treatment used on a variety of objects within the collection. This treatment can also be carried out on a variety of scales. The one discussed was on the larger side and took time to construct and prep before the actual treatment with nitrogen started. Instead of taking the object to the chamber, the chamber was built around the object with a Rentokil 6 m3 PVC reusable bubble. A skeletal structure from PVC tubes were constructed around the object so the chamber would not collapse on top of the object during the nitrogen treatment. A Liquid Nitrogen Dewar was used to hookup to the chamber as well as an oxygen monitor, and their home-made “bubbler”. The home-made “bubbler” was constructed to adjust the flow of humidification. To create the “bubbler”, it took about one week to build which included ordering the equipment. The construction of the chamber took about 2 days to build, and the time to flush the atmosphere to the correct percentage took between 2-5 hours.
Bret Headley from Headley Conservation Service, LLC discussed his anoxic treatment using a nitrogen-based system. The object he was treating could not fit into a freezer, so an alternative treatment was constructed. Headley highly recommends the Inert Gases in the Control of Museum Insect Pests by Charles Selwitz and Shin Maekawa (Getty Conservation Institute, 1998) when researching treatments such as the ones discussed during this panel. This treatment was also built around the object using barrier film along with the appropriate hookups for the gases and monitors.
Eric Breitung from the Metropolitan Museum of Art discussed an anoxic treatment using argon and oxygen. The setup also used MarvelSeal 360 for the chamber around the object with a hose hookup to the chamber which included the argon tank with a flow meter, water bubbler as well as an oxygen monitor. The MarvelSeal 360 was heat sealed for the treatment, and this mechanism took about 1-2 hours to setup which does differ with the size of the object. When flushing out the system it took about 1.5-4 hours for a smaller object and 4-20 hours for larger objects. The amount of time to leave the objects in the chamber was about 4 weeks which was based on kill times from the Getty Conservation Institute publications.
What I found most interesting in these types of pest control treatments, is it offered other options instead of using freezing or thermal techniques. The conservators in the panel were able to share and discuss their findings and the supplies they have found most effective. After all the presentations, the conservators were asked two survey questions about their treatments (Tables 1-3). I look forward to hearing and seeing more anoxic treatments and techniques. Thank you to everyone involved with this discussion!