Hi Lindsey, You are right. The key is that paper acclimated to moderate relative humidity (30 to 60%RH) contains much more water than air (about 7% w/w at 50%RH). In a box as you describe the moisture content of the paper will hardly change at all during temperature changes and the paper will buffer the RH of the surrounding air. It will only be the transient temperature gradients during cooling and warming that could result in condensation or frost formation on surfaces that are much colder than the adjacent air. If your experience demonstrates this is not a problem, and the ratio of paper to air does not vary greatly (by a factor of x10 or more) then I think you can be confident in not being concerned about transient moisture damage. Best, Rob ________________________________ From: 'Lindsey Gibson' via MuseumPests <[email protected]> Sent: Wednesday, February 11, 2026 8:34 AM To: [email protected] <[email protected]> Subject: RE: [EXTERNAL]:[PestList] Re: Request for advice on packaging archives for freezing
Thanks very much for your responses Rob and Riika. I thought that as long as I fill the boxes and wrap the items in tissue withing the boxes, as long as the boxes are moisture tight, this should work the same as my current system of tissue wrapping and sealing in plastic to mitigate the risks of moisture in the air. With regard to the moisture content of the paper, i wonder if as long as the books/paper are dry, and have an absorbant wrapper (the acid free tissue) hopefully this will prevent any condensation damaging the books/paper? I certainly have not previously had any noticeable issues when freezing paper items this way. Please do correct me if I have misunderstood though. Thanks very much, Lindsey From: [email protected] <[email protected]> On Behalf Of Robert Waller Sent: 06 February 2026 16:13 To: [email protected] Subject: [EXTERNAL]:[PestList] Re: Request for advice on packaging archives for freezing You don't often get email from [email protected]<mailto:[email protected]>. Learn why this is important<https://aka.ms/LearnAboutSenderIdentification> CAUTION: This email originated from outside of the organization. Do not click links or open attachments unless you recognize the sender and know the content is safe. Thanks Riikka, I also have a concern about too much air space but for me it is a different concern. I expect the paper will hold more moisture than the air, typically about 7% w/w (70 g/kg) at 20°C and 50%RH where air at 20°C and 50%RH just holds about 0.09 g/L. As the package cools the amount of moisture held within the paper will increase slowly, but frost on the inside surface of the container would likely develop first. Depending on how thermal gradients first develop, then subside over time, there might be a chance of some inside box surface frost melting during the warming process and causing some of wetting to collection item surfaces. I don't know if it would be a serious concern but I expect it could happen to some extent, especially when there is a large airspace to paper content ratio. Rob Protect Heritage Corp. Ottawa ________________________________ From: [email protected]<mailto:[email protected]> <[email protected]<mailto:[email protected]>> on behalf of Riikka Lastikka <[email protected]<mailto:[email protected]>> Sent: Tuesday, February 3, 2026 10:14 AM To: [email protected]<mailto:[email protected]> <[email protected]<mailto:[email protected]>> Subject: [PestList] RE: Request for advice on packaging archives for freezing Dear Lindsey, I guess that if the boxes would be filled with something to minimize the amount of air inside the box, your idea might work. What I have understood is that depending of the amount of moisture in the air while you are packing the material has an effect on it how much moisture that would be in the box inside a freezer – the colder it gets, the moister the air becomes, and the more free airspace there is inside the box, the moister it can become. Not specifically problem during freezing but bigger while taking the material out of the freezer. I would be interested in to see what kind of boxes you have found. Do you have a link to them? Thank you! Riikka Lastikka Paper Conservator Åbo Akademi University Library Turku Finland From: 'Lindsey Gibson' via MuseumPests <[email protected]<mailto:[email protected]>> Sent: tisdag 3 februari 2026 16:59 To: [email protected]<mailto:[email protected]> Subject: [PestList] Request for advice on packaging archives for freezing Good afternoon, I have a query about packaging materials for freezing. I routinely freeze paper/books/textiles to deal with insect pests. I wrap in acid free tissue and polythene sealed with self adhesive tape. I reuse the polythene as much as possible but it does need replacing periodically and I’m using fresh self adhesive tape (with a plastic carrier) each time. As a lot of the books and papers I am freezing are similar sized, I was wondering if I could use airtight, watertight plastic boxes instead of polythene and tape. I have found some boxes that are IP56 compliant. I can’t immediately think of a reason this wouldn’t work but am keen to hear from others who may think of an issue with this/ or who have used boxes themselves instead of polythene. Thanks very much, Lindsey ________________________________ Customer Notice We have recently updated our terms and conditions for all our services, including making some important updates to our privacy notices. 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