Hi everyone, Alyssa brings up some good questions and better yet a good list of reasons to wrap items for low temperature treatment. I agree with the responses posted already and I know there will be more. At my institution we freeze nearly all incoming organic items. We routinely wrap larger items with 4 mil polyethylene sheet and freezer safe tape, and use Ziploc type bags for smaller items. We do re-use the plastic and the bags. A couple of other things - I think plastic sheeting and bags takes less room to store than containers. Sheeting/bags are also good because they are transparent and can be used for monitoring items that can't be frozen.
I think all of these concerns are addressed in Tom Strang's CCI note on low temperature treatment as well as in other literature such as Mary-Lou Florian's "Heritage Eaters" and others. As you all know the museumpest.net site is being re-worked as we speak, this resource and much more will be readily available very soon. For now here is the link from CCI http://www.icc-cci.gc.ca/crc/notes/pdf-documents/n3-3_e.pdf I would test Tupperware/Rubbermaid type containers to be sure they really are vapor proof. One could also wrap the such a container with stretch wrap at the closure it is a good seal. Stretch wrap is inexpensive and easy to use. A few specific comments on Alyssa's top 5 reasons ... 1.To contain infestation while transporting specimen to the freezer a. - not just transport to freezer - anytime an item is suspected of being infested or even possibly infested it should be wrapped or contained anyway. 2. To prevent moisture content changes in the object during freezing, which could result in dimensional changes and physical damage - a. This is not really such an issue - lots of literature on this subject worth reading 3. To prevent damage from possible freezer failure (water drips/ floods, debris from ceiling) a. Absolutely! 4. . To prevent condensation from forming during its acclimatization before the bag is opened a. Yes! That is the main reason for wrapping and for making the wrapping airtight! General guideline is always wait at least 24 hours to allow items to come to room temperature before opening. 5. To prevent (or slow) re-infestation during acclimatization a. I agree with Tom Parker on this one - there should be no reason for re-infestation unless freezing temperature was not adequate or items are returned unwrapped to an area that still has active or suspect activity. One can always leave items wrapped after freezing if, for example, on is still working on cleaning infested area. Best wishes to all, Emily Emily Kaplan Conservator Smithsonian National Museum of the American Indian Cultural Resources Center Suitland, MD 20746 tel 301-238-1418 fax 301-238-3201 [email protected] From: [email protected] [mailto:[email protected]] On Behalf Of Dee Stubbs-Lee Sent: Thursday, June 04, 2009 8:23 AM To: [email protected] Subject: RE: [pestlist] Wrapping infested objects for freezing At our museum, the practice is to routinely wrap and freeze most material coming in from outside the building (there is quite a lot of it as our exhibitions and collections storage are in separate buildings) in a walk in freezer unless the items are felt to be at high risk of damage from freezing. Our collections storage facility, like many, is overcrowded and infestations could potentially spread quickly -- we feel the risk of infestation outweighs the risk of damage of freezing most collections objects. I share Alyssa's concern about the wastefulness of using plastic only once (we use polyethylene sheeting, sealed with packaging tape), and we do sometimes reuse larger pieces of plastic for that reason. The idea of using a reusable freezing container sounds appealing on many levels, however, I have always been under the impression that it is important to: a) eliminate any extra air in the "bag", and b) seal the "bag" so that it is airtight Both of those would be difficult in the case of any reusable see-through container or bag that I can imagine. Any thoughts? Dee Stubbs-Lee, CAPC, MA Conservator, The New Brunswick Museum 277 Douglas Avenue Saint John, New Brunswick Canada E2K 1E5 telephone: (506) 643-2341 fax: (506) 643-2360 e-mail: [email protected] www.nbm-mnb.ca -----Original Message----- From: [email protected] [mailto:[email protected]]on Behalf Of [email protected] Sent: June 3, 2009 8:35 PM To: [email protected] Subject: Re: [pestlist] Wrapping infested objects for freezing Alyssa - You pose a lot of good questions about wrapping before freezing. I think the foremost reason from wrapping is to prevent ice crystal formation on the surface of the object being frozen. Using any kind of wrap, such as muslin, kraft paper, cotton cloth, etc. will prevent this from happening. Most use zip-lock type bags, which can be re-used. If something has been properly frozen, the wrapping will not be "contaminated" and can be re-used. For larger mounts, you may want to consider constructing a framework "box" with polyethylene stapled to the 5 sides, and a Velcro fastening system for the final side for putting the mount inside and then sealing it with the Velcro attached to the perimeter of the polyethylene. This framework can therefore be used again and again. I can't imagine the object being reinfested after being properly frozen as it sits on a countertop acclimatizing; no institution has that rampant an infestation which would cause almost immediate reinfestation. Tom Parker -----Original Message----- From: Becker, Alyssa TPCS <[email protected]> To: [email protected] Sent: Wed, 3 Jun 2009 6:17 pm Subject: [pestlist] Wrapping infested objects for freezing Hello, Here at the Royal Saskatchewan Museum I wrap anything to be treated for insect pest infestation in polyethylene plastic prior to freezing. These objects are most often natural history specimens (mounts) and textiles or leather/hide/feathered objects from our Aboriginal History collection. Lately this practise has come into question - is it not a waste of time and resources to do this, especially since much of the plastic must be thrown away to prevent possible cross-contamination? Could the wrapping stage be eliminated for adsorbent objects in good condition? My reasons to continue wrapping are listed below. However, I wanted to pose these questions to the list for thoughts, from a practical point of view, as to whether wrapping is important, and if so, how and when. Has anyone has come up with a more environmental alternative? For example, has anyone found a line of vapour -proof, washable tubs that would do the same job for a variety of sizes of mounts? Reasons for wrapping: 1. To contain infestation while transporting specimen to the freezer 2. To prevent moisture content changes in the object during freezing, which could result in dimensional changes and physical damage 3. To prevent damage from possible freezer failure (water drips/ floods, debris from ceiling) 4. To prevent condensation from forming during its acclimatization before the bag is opened 5. To prevent (or slow) re-infestation during acclimatization Your thoughts and ideas on the subject would be most appreciated! Sincerely, Alyssa Becker Conservator Royal Saskatchewan Museum 2340 Albert Street Regina, Saskatchewan S4P 2V7 P: 306-787-2667 F: 306-787-2645 [email protected] ________________________________ Wanna slim down for summer? Go to America Takes it Off <http://www.aolhealth.com/diet/weight-loss-program/?ncid=emlcntusheal000 00001> to learn how.
