Re: [pestlist] question about freezing

[Molly Gleeson]

Thanks everyone for your advice/suggestsions.  And I really wanted to find Tom Strang's article--I didn't realize you could download it as a sample on the CCI website--good to know, and thinks for sending me the link.  The graphs he provides are really great and just what I was looking for. 

 

I guess this freezer company we're using charges a lot more for temperatures below -17C because it involves moving them into their blast freezer.  I don't know why their standard freezers don't go below that temp.--our own chest freezer is currently set at -30C.  This is good information for me to give to our director to support possibly using a different company. 

 

And also, we have built an anoxic chamber to treat some objects, but unfortunately, this project involves massive treatment of 5000+ textiles, so I think freezing is our best option at this point. 

 

Thanks again for your input--I really appreciate it. 

 

Molly

----- Original Message ----
From: Gretchen Anderson <[EMAIL PROTECTED]>
To: pestlist@museumpests.net
Cc: Molly Gleeson <[EMAIL PROTECTED]>
Sent: Wednesday, October 15, 2008 7:33:39 AM
Subject: Re: [pestlist] question about freezing

Yes, -20 deg C is considered the critical temperature.  Testing on kill rates for all life cycle stages have been done by Tom Strang at the Canadian Conservation Institute (CCI)
http://www.cci-icc.gc.ca/publications/ccinotes/pdf-documents/3-3_e.aspx

Other research being done in Sweden has shown a significant drop in fertility rates for insect eggs that are put through the freezing process.  See a review of this on line at http://www.spnhc.org/files/CF18-1_2.htm.  It is the last entry -- (sorry I cannot get the link to work)
PROCEEDINGS OF THE 3RD NORDIC SYMPOSIUM ON INSECT PEST CONTROL IN MUSEUMS, 1998, M. Akerlund, J. Bergh, A. Stenmark, and I. Wallenborg, eds.

I am surprised to hear that the freezer company is charging higher rates for -20 deg C since most household freezers reach the critical temperature.  Freezing should be done in a freezer that is not self-defrosting.

Good luck!

Gretchen Anderson
Conservator
Science Museum of Minnesota
651-221-4764
[EMAIL PROTECTED]
www.smm.org

----- Original Message -----
From: "Margaret Geiss-Mooney" <[EMAIL PROTECTED]>
To: pestlist@museumpests.net
Cc: "Molly Gleeson" <[EMAIL PROTECTED]>
Sent: Tuesday, October 14, 2008 6:46:10 PM GMT -06:00 US/Canada Central
Subject: RE: [pestlist] question about freezing

Good afternoon, PestListers – My understanding of the freezing process is that freezing if done correctly also kills the eggs, very important when you are dealing with infested textiles.

 

Check out the following NPS ConserveOGram on freezing:

http://www.nps.gov/history/museum/publications/conserveogram/03-06.pdf

 

It appears that you do need to get that freezer temperature done to -20C for 48 hours. Rapid cooling to -20C is also necessary to assure a complete kill. The ConserveOGram covers the whole procedure very well.

 

Depending on your budget and your staffing, perhaps anoxic treatment should be considered?

Regards,

Meg

._ _ _ _ _ _ _ _ _ _ _ _     ______    

Margaret (Meg) Geiss-Mooney    

Textile/Costume Conservator in Private Practice

 in beautiful Northern California    

Professional Associate, AIC    

[EMAIL PROTECTED]

---

…are in a freezer that is set at 0 F (-17 C).  We are in the process of packing the other half in preparation to move them into the freezer as well.  I would like them to be frozen in a freezer set to at least -20 C, however, the freezer company quoted exhorbitant fees for lowering the temperature of the freezer, even for only a few days.  I'm concerned that -17 C isn't cold enough to ensure that the moths are killed, even if we keep them in the freezer for several weeks.  Is this true? 

 

I'm also thinking that we should do a second freeze, to ensure that all life stages are killed, but if the temperature is not low enough, then maybe this is pointless.  I plan to do a test by putting a bag of live moths/larvae into the freezer along with the objects, to monitor what's happening, but does anyone have any experience with this, or have any suggestions about adjusting the temperature and also about the recommended length of time to freeze at -17C to ensure mortality of the moths? 

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