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  • 1.  Freezing to Inactivate Mold

    Posted 08-20-2025 16:50

    Hi all,

    We have a wooden object that I am concerned may have active mold on it, and I was thinking I would freeze it to inactivate the mold and then be able to vacuum it with our Nilfisk vacuum cleaner. (The object is a recent donation, and I believe it was contaminated at the time of acceptance though we didn't realize it. It thankfully does not appear to have spread.)

    I have used the freezer method before, but not with wood, so I was wondering if this is an acceptable treatment? The object is a wooden box that holds a microscope. The box is certainly not as significant as the microscope itself, but it is original to it, so I'd like to save it. However, I don't see my board putting significant resources towards professional conservation in this instance, so I am trying to do the best I can in-house. I'd appreciate any advice/suggestions. Thank you!



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    Stephanie Lee
    Curator
    Arlington Heights Historical Museum
    Arlington Heights
    United States
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  • 2.  RE: Freezing to Inactivate Mold

    Posted 08-21-2025 12:18

    Hi Stephanie,

    Wood artifacts are routinely frozen for dealing with pest infestations and so there should be no issues in freezing your microscope box. When items are frozen for pest remediation we recommend that they are wrapped in plastic to prevent damage from condensation that forms when the items are taken out of the freezer and allowed to come back to room temperature. I also want to correct a misconception - freezing will not "inactivate" mold. What it will do is buy you time to determine a course of treatment without the mold progressing. This is why freezing is recommended for wet items that are susceptible to mold growth. In your case, if you don't have time to do a thorough cleaning the you can freeze or simply ensure that the item is in a lower RH environment that will not promulgate the mold growth and that the mold spores aren't spreading to nearby items. Otherwise, you can proceed with cleaning without freezing at all.

    Best, Rachael   



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    Rachael Arenstein
    A.M. Art Conservation, LLC
    rachael@amartconservation.com
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    Original Message


  • 3.  RE: Freezing to Inactivate Mold

    Posted 08-21-2025 13:52

    Hi Stephanie, 

    My name is Maddie, and I am the C2CC Monitor this week. I echo Rachael's point that freezing will buy you time, but not necessarily kill or inactivate the spores. It is just as effective (and certainly easier) to deactivate any spores by placing the box in a lower RH environment for several days before cleaning inactive spores with a HEPA filtered vacuum. The Canadian Conservation Institute has some helpful guidance on this in the Deactivation section of this technical bulletin https://www.canada.ca/en/conservation-institute/services/conservation-preservation-publications/technical-bulletins/mould-prevention-collection-recovery.html#a3cd. 

    Best, 

    Maddie



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    C2CC Monitor
    Madeline Cooper
    Preventive Conservator
    MC Conservation
    Philadelphia PA
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    Original Message


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