[Nhcoll-l] [MOGELIJK SPAM ! *****] Re: Freezing specimens in spirit

Thu Aug 6 05:56:31 EDT 2020

Dear Tonya,

In addition to Dirk's and Simon's remarks:

If you freeze glass jars holding ethanol 70, they will implode due to the 30-40 times higher expansion coefficient of ethanol compared to that of glass.

If you freeze glass jars holding formalin, they will explode due to formation of ice (crystals).

Fluid preserved specimens should always be stored at constant temperature, preferably between 18 and 22 °C (temperature the users are motivated to work on the collections 😉 ).

Kind regards,

Dries

Andries J. van Dam | conservator

Museum of Anatomy | Leiden University Medical Center | Building 3 (V3-32)

P.O.Box 9600 | 2300 RC Leiden | The Netherlands

Visiting address: Hippocratespad 21 | Tel: +31 (0)71 52 68356 | E-mail: A.J.van_Dam at lumc.nl<https://mail.lumc.nl/owa/redir.aspx?C=O7wgy__4qEq-bCzDQhMP7IpMG33lsdEIUTcpXTatWwljNFWdpbtnBKj-HeYnbumJrkd3hILExAk.&URL=mailto%3aA.J.van_Dam%40lumc.nl>

Scientific associate | Natural History Museum London | http://www.nhm.ac.uk<https://mail.lumc.nl/owa/redir.aspx?C=O7wgy__4qEq-bCzDQhMP7IpMG33lsdEIUTcpXTatWwljNFWdpbtnBKj-HeYnbumJrkd3hILExAk.&URL=http%3a%2f%2fwww.nhm.ac.uk%2f>

________________________________
Van: Nhcoll-l <nhcoll-l-bounces at mailman.yale.edu> namens Simon Moore <couteaufin at btinternet.com>
Verzonden: donderdag 6 augustus 2020 10:41:37
Aan: Neumann, Dirk
CC: nhcoll-l at mailman.yale.edu
Onderwerp: [MOGELIJK SPAM ! *****] Re: [Nhcoll-l] Freezing specimens in spirit

Hi Tonya,

Just to say that Dirk’s suggestions are all good and that alcohol neutralises fungus anyway, unless the concentration falls below c. 30%. Freezing jars is not a good idea (def a non-no for me too) and that fungal spores are ubiquitous; you just have to rely on prevention.

With all good wishes, Simon.

Simon Moore MIScT, RSci, FLS, ACR
Conservator of Natural Sciences and Cutlery Historian,

www.natural-history-conservation.com<http://www.natural-history-conservation.com>

> On 6 Aug 2020, at 07:58, Dirk Neumann <neumann at snsb.de> wrote:
>
> Hi Tonya,
>
> there are surely a couple of things here:
>
> 1. Depending which jars and closures you use in your collection, you will have different expansion coefficients. Containers for cryo-storage usually consider this (and some even will get properly tight when frozen and the lid shrinks under cold temperatures to give a proper fit), but jars we normally use in our collections are not designed for such cold temperatures. Freezing them, could cause considerable damage to jars and/or lids and may lead to high replacement costs in the long run.
>
> 2. Lipids, oils, fats and other dissolved components might coagulate. For example in insect collections, waxy deposits are commonly observed when specimens are frozen (e.g. -25°C). These deposits will not disappear when the specimens are thawed again but remain, covering all the filigree appendices, antennae, etc. In larger specimens, e.g. fish, it could lead to e.g to cholesterol deposits on specimens. So again, you surely would introduce more damage when freezing the jars.
>
> 3. Changing the temperature regime also influences the chemical equilibrium that formed inside specimen jars. Besides lipids and oils, lower temperatures usually decrease the capacity of the preservation fluid to keep organic compounds in solution. This often triggers crystallisation processes, e.g. residual dissolved formaldehyde may form paraformaldehyde needles.
>
> Carrying potential pests into your new storage with the jars would only be possible if you would move a lot of organic material into your new storage area. Some organic material, such as historic big bladder seals, are also very vulnerable to low temperatures (shrinkage). So if there are no organic deposits on your jars, there wouldn't be much nutrients that could be carried. Vice versa, if there would be dust on the jar (as we have currently because of major renovation works going on in our collection), cleaning jars with a damp cloth should do the job. You should be careful with external labels in this case, but usually any 'dirt' would be on the top. In case of stoppered jars or jars with historic seals, you probably would need to be careful with damp cleaning.
>
> Hope this helps,
>
> and good progress with your moving!
>
> With best wishes
> Dirk
>
>
> Am 06.08.2020 um 08:25 schrieb Haff, Tonya (NCMI, Crace):
>> Hi all,
>>
>> I have a question for you about freezing whole jars of specimens – what do you think the effect would be, and would you recommend it? My gut says NOOOOOOOO this is a terrible idea, but it has been suggested as a shortcut to kill potential pests before we move the collection into a new building. I personally think that the main thing we don’t want to move into a new EtOH vault is mould, whose spores won’t be killed by freezing anyway. But, I am open to ideas and I wanted to check with other people before loudly stamping down my foot…
>>
>> Thanks!
>>
>> Tonya
>>
>> ---------------------------------------------------------
>> Dr Tonya Haff
>> Collections Manager
>> Australian National Wildlife Collection
>> National Research Collections Australia, CSIRO
>> Canberra, Australia
>> Phone: (+61) 02 6242 1566 (office)
>> (+61) 0419 569 109 (mobile)
>>
>> I am in Thursdays and Fridays
>> Please call or text my mobile for a fast reponse Monday – Wednesday
>>
>>
>>
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>
>
> --
> <ihlhajmlandjfcak.png>
>
>
> Dirk Neumann
>
> Tel: 089 / 8107-111
> Fax: 089 / 8107-300
> neumann(a)snsb.de
>
> Postanschrift:
>
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>
> Besuchen Sie unsere Sammlung:
> http://www.zsm.mwn.de/sektion/ichthyologie-home/
>
> ---------
>
> Dirk Neumann
>
> Tel: +49-89-8107-111
> Fax: +49-89-8107-300
> neumann(a)snsb.de
>
> postal address:
>
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>
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>
>
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NHCOLL-L is brought to you by the Society for the Preservation of
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mission is to improve the preservation, conservation and management of
natural history collections to ensure their continuing value to
society. See http://www.spnhc.org for membership information.
Advertising on NH-COLL-L is inappropriate.
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