[Nhcoll-l] Glycerol as a safer alternative to ethanol for display specimens - Feedback from your practice?

Tue Jun 24 10:23:12 EDT 2025

Dear all,

I was following your conversation out of interest and I am curious why you
would not want to add a biocide to scientific specimens? Is it damaging? I
ask this because we have our largest specimens in a tank in glycerol,
because ethanol was no option (in terms of fire hazard and health and
safety). And we added a lot of thymol to keep mold out...Also all the
'cleared and stained' specimens in the collection all have some biocide
added to them.

Thanks!

Esther Dondorp
Collectiebeheerder reptielen, amfibieën en vissen
*absent on Wednesdays*
Monday, Tuesday, Thursday, Friday
<https://naturalis-public-media-assets.s3.eu-central-1.amazonaws.com/Naturalis-mail-signature/logo.png>

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Op di 24 jun 2025 om 16:12 schreef John E Simmons <simmons.johne at gmail.com>:

> I agree with Dirk--without a very good seal on the containers, the
> glycerol will likely absorb moisture from the air, introducing both
> airborne contaminants into the containers and possibly causing them to
> overflow (I have had both happen to containers of specimens in glycerin
> that were not properly sealed).
>
> Because these specimens do not have scientific value, you should also
> consider adding a biocide to the glycerol such as a few crystals of thymol
> or a bit of camphor (as recommended by Simon Moore).
>
> --John
>
> John E. Simmons
> Writer and Museum Consultant
> Museologica
> *and*
> Investigador Asociado, Departamento de Ornitologia
> Museo de Historia Natural, Universidad Nacional Mayor de San Marcos, Lima
>
>
> On Tue, Jun 24, 2025 at 9:40 AM Marion BILLOT <Marion.Billot at geneve.ch>
> wrote:
>
>> Dear colleagues,
>>
>>
>>
>> I am currently working on an exhibition project involving fluid-preserved
>> specimens, and I am exploring the possibility of replacing ethanol with
>> glycerol for long-term display purposes. The main objective is to reduce
>> fire hazards and mitigate health risks in display environments (cases that
>> are not airtight).
>>
>>
>>
>> I am preparing to present this proposal internally. As this practice is
>> not yet established in my institution and tends to raise concerns, I would
>> be very grateful for any feedback from professionals who have experience
>> using glycerol in this context.
>>
>>
>>
>> To clarify:
>>
>>    - The specimens are of strictly pedagogical value, they are not
>>    scientifically rare or culturally significant.
>>    - We aim for long-term display in semi-sealed cases with limited air
>>    exchange.
>>    - I understand that transferring specimens from ethanol to glycerol
>>    requires several days of transitional baths in demineralized water to avoid
>>    osmotic shock and tissue damage. I am considering a gradual transition:
>>    ethanol 70 % → 50 % → 30 % → 10 %, followed by glycerol in increasing
>>    quart-step dilutions. I will let it in a minimum of 4 hours for small
>>    specimen (5 cm).
>>
>>
>>
>> Have you used glycerol for display purposes in your institution? If so,
>> under what conditions, and with what types of specimens? Any technical
>> advice, protocol suggestions, or reference materials would be most
>> appreciated.
>>
>>
>>
>> Thank you very much in advance for your insights. They will be very
>> helpful in supporting a safer and more sustainable exhibition strategy.
>>
>> Best regards,
>>
>>
>>
>> Marion
>>
>>
>>
>>
>> Marion BILLOT
>> Collaboratrice support scientifique
>> Invertébrés
>> T. +41 22 418 6459
>> marion.billot at geneve.ch Muséum d'histoire naturelle (MHN)
>> Département de la culture et de la transition numérique
>> Route de Malagnou 1
>> 1208 Genève
>> www.museum-geneve.ch <http://command%20not%20present>
>> <http://command%20not%20present>
>> Notre environnement est fragile, merci de n'imprimer ce message qu'en cas
>> de nécessité.
>>
>>
>>
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