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    <p>Dear Esther, dear Marion,</p>
    <p>Sorry for the late response, very interesting topic indeed. </p>
    <p>I have transferred a few collections into glycerol with very good
      results (i'm currently working on another collection doing this at
      the moment). My first try was done by a simple protocol that I got
      from Andries van Dam back in 2018, after he presented the use of
      Glycerol as a alternative preservation fluid at the PFC2018 in
      Paris. The use of glycerol goes back to the times of Carl
      Kaiserling (1869-1942) and Leonhard Jores (1866-1935), both German
      pathologists that presented their potential as preservation fluid
      over 120 years back in the field of anatomical preparation.
      Besides a few publications from Andreis van Dam (Maclead & Van
      Dam 2011; Van Dam 2020), there is not much resent research into
      this mater that i'm aware of. I will hopefully be able to publish
      something in a soon future. Andries and I did a nice presentation
      at a meeting organized by the German conservators/restorers
      society (VDR) last year, but there is no real conference paper
      available.<br>
    </p>
    <p>
    </p>
    <p>The glycerol solution concentration is crucial, specimens have to
      be transferred into a 65% solution of glycerol in water. By this,
      the mentioned absorption of humidity is inhibited since the
      solution is "saturated" with water and there should be no
      absorption of water from the environment. Glycerol solution with
      much higher content of glycerol (80-95%), can indeed absorb
      moisture from the surrounding environment, specially if poorly
      sealed. But if the transfer in steps into 65% of glycerol is made
      correctly, there is no need for any kind of fungicide in the
      preservation fluid. This is actually the biggest advantage of
      using glycerol in the first place (besides fire hazards, toxicity
      issues and/or evaporation), since it enables the use of a toxin
      free preservation fluid. Cleared specimens stored in higher
      glycerol concentrations, can be transferred into a 65% glycerol
      solution as well. Other mentioned issues like the slight color
      change, are of course things to be taking into account before the
      transfer. Besides that it is a really sticky job.<br>
    </p>
    <p>Important things to take account are: big specimens that will
      take a long time to transfer from one step into another; a very
      good plan of transfer between fluids, since specimens will take
      different amount of time to transfer depending on their volume;
      the size of the receptacles for the transfer, since a good
      transfer requires a much higher ratio of fluid to specimen in
      order to enable a fast diffusion of the fluid; and of course the
      final container, since a good sealing is essential for the
      preservation of fluid preserved specimens. <br>
    </p>
    <p>I would be super happy to provide you with a protocol, even tough
      this has to be adapted to the specific collection, depending on
      specimen size, tissue type and so on. Just let me know.</p>
    <p>All the best,<br>
    </p>
    <p><br>
    </p>
    <p>Literature cited: <br>
    </p>
    <p>Van
      Dam, A.: Finding a cure for hazardous collections: the road to
      zero formaldehyde and ethanol. In: Collection Forum (34). 2020. S.
      118–123.
    </p>
    <div
style="language:de;margin-top:0pt;margin-bottom:0pt;margin-left:.31in;
text-indent:-.31in;text-align:justify;text-justify:inter-ideograph;direction:
ltr;unicode-bidi:embed;vertical-align:baseline;mso-line-break-override:restrictions;
punctuation-wrap:simple">Macleod,
      I.; Van Dam, A.: A migration mechanism for transfer of sharks from
      ethanol to
      aqueous glycerol solutions. Conference Paper. ICOMCC Lisbon 2011.
      <br>
    </div>
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style="language:de;margin-top:0pt;margin-bottom:0pt;margin-left:.31in;
text-indent:-.31in;text-align:justify;text-justify:inter-ideograph;direction:
ltr;unicode-bidi:embed;vertical-align:baseline;mso-line-break-override:restrictions;
punctuation-wrap:simple"><br>
    </div>
    <div class="moz-cite-prefix">Am 24.06.25 um 16:23 schrieb Esther
      Dondorp:<br>
    </div>
    <blockquote type="cite"
cite="mid:CAGaR2xdaLybZgt6g6UuQ9RQ3R3XncbAsQK=dxL4o=b+fqPT=7A@mail.gmail.com">
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          <div>Dear all,</div>
          <div><br>
          </div>
          <div>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.</div>
          <div><br>
          </div>
          <div>Thanks!</div>
          <div><br>
          </div>
          <div>
            <div dir="ltr" class="gmail_signature"
              data-smartmail="gmail_signature">
              <div dir="ltr">
                <div><span style="font-size:10pt">Esther Dondorp</span></div>
                <div><span style="font-size:10pt">Collectiebeheerder
                    reptielen, amfibieën en vissen</span></div>
                <div>
                  <div style="color:rgb(34,34,34)"><font size="1"><i>absent
                        on Wednesdays</i></font></div>
                  <div style="color:rgb(34,34,34)"><font size="1">Monday,
                      Tuesday, Thursday, Friday</font></div>
                </div>
                <div><span
                    style="font-family:arial,helvetica,sans-serif"><a
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href="https://naturalis-public-media-assets.s3.eu-central-1.amazonaws.com/Naturalis-mail-signature/logo.png"
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                <p><br>
                  <br>
                  <br>
                  <br>
                  <br>
                  <span style="font-size:8pt"><sub> - -</sub></span><br>
                  <span style="font-size:8pt"><sub><a
                        href="mailto:esther.dondorp@naturalis.nl"
                        target="_blank" moz-do-not-send="true"
                        class="moz-txt-link-freetext">esther.dondorp@naturalis.nl</a>
                      - <a href="https://www.naturalis.nl/"
                        target="_blank" moz-do-not-send="true">www.naturalis.nl</a></sub></span><br>
                  <span style="font-size:8pt"><sub>Darwinweg 2, 2333 CR
                      Leiden</sub></span><br>
                  <span style="font-size:8pt"><sub>Postbus 9517, 2300 RA
                      Leiden</sub></span></p>
                <div><a href="https://www.naturalis.nl/" target="_blank"
                    moz-do-not-send="true"><img
src="https://naturalis-public-media-assets.s3.eu-central-1.amazonaws.com/Naturalis-mail-signature/signature-gif.gif"
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                <div> </div>
              </div>
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          </div>
          <br>
        </div>
        <br>
        <div class="gmail_quote">
          <div dir="ltr" class="gmail_attr">Op di 24 jun 2025 om 16:12
            schreef John E Simmons <<a
              href="mailto:simmons.johne@gmail.com" target="_blank"
              moz-do-not-send="true" class="moz-txt-link-freetext">simmons.johne@gmail.com</a>>:<br>
          </div>
          <blockquote class="gmail_quote"
style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
            <div dir="ltr">
              <div>
                <div
style="font-family:tahoma,sans-serif;font-size:small;color:rgb(0,0,0)"
                  class="gmail_default">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). </div>
                <div
style="font-family:tahoma,sans-serif;font-size:small;color:rgb(0,0,0)"
                  class="gmail_default"><br>
                </div>
                <div
style="font-family:tahoma,sans-serif;font-size:small;color:rgb(0,0,0)"
                  class="gmail_default">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).</div>
                <div
style="font-family:tahoma,sans-serif;font-size:small;color:rgb(0,0,0)"
                  class="gmail_default"><br>
                </div>
                <div
style="font-family:tahoma,sans-serif;font-size:small;color:rgb(0,0,0)"
                  class="gmail_default">--John</div>
                <br clear="all">
              </div>
              <div>
                <div dir="ltr" class="gmail_signature">
                  <div dir="ltr">
                    <div>
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                        <div>
                          <div dir="ltr">
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                                                    <div>
                                                      <div dir="ltr"><font
                                                          size="2"><span
style="font-family:tahoma,sans-serif">John E. Simmons<br>
                                                          Writer and
                                                          Museum
                                                          Consultant</span></font></div>
                                                      <div dir="ltr"><font
                                                          size="2"><span
style="font-family:tahoma,sans-serif">Museologica<br>
                                                          <i>and</i><br>
                                                          Investigador
                                                          Asociado,
                                                          Departamento
                                                          de Ornitologia<br>
                                                          Museo de
                                                          Historia
                                                          Natural,
                                                          Universidad
                                                          Nacional Mayor
                                                          de San Marcos,
                                                          Lima</span></font><br>
                                                      </div>
                                                    </div>
                                                  </div>
                                                </div>
                                              </div>
                                            </div>
                                          </div>
                                        </div>
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                            </div>
                          </div>
                        </div>
                      </div>
                    </div>
                  </div>
                </div>
              </div>
              <br>
            </div>
            <br>
            <div class="gmail_quote">
              <div dir="ltr" class="gmail_attr">On Tue, Jun 24, 2025 at
                9:40 AM Marion BILLOT <<a
                  href="mailto:Marion.Billot@geneve.ch" target="_blank"
                  moz-do-not-send="true" class="moz-txt-link-freetext">Marion.Billot@geneve.ch</a>>
                wrote:<br>
              </div>
              <blockquote class="gmail_quote"
style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
                <div>
                  <div lang="FR-CH">
                    <div>
                      <p class="MsoNormal">Dear colleagues,</p>
                      <p class="MsoNormal"> </p>
                      <p class="MsoNormal">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).</p>
                      <p class="MsoNormal"> </p>
                      <p class="MsoNormal">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.</p>
                      <p class="MsoNormal"> </p>
                      <p class="MsoNormal">To clarify:</p>
                      <ul style="margin-top:0cm" type="disc">
                        <li style="margin-left:0cm">The specimens are of
                          strictly pedagogical value, they are not
                          scientifically rare or culturally significant.</li>
                        <li style="margin-left:0cm">We aim for long-term
                          display in semi-sealed cases with limited air
                          exchange.</li>
                        <li style="margin-left:0cm">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<span
                            style="font-family:Arial,sans-serif"> </span>%
                          → 50<span style="font-family:Arial,sans-serif"> </span>%
                          → 30<span style="font-family:Arial,sans-serif"> </span>%
                          → 10<span style="font-family:Arial,sans-serif"> </span>%,
                          followed by glycerol in increasing quart-step
                          dilutions. I will let it in a minimum of 4
                          hours for small specimen (5 cm).</li>
                      </ul>
                      <p> </p>
                      <p class="MsoNormal">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.</p>
                      <p class="MsoNormal"> </p>
                      <p class="MsoNormal">Thank you very much in
                        advance for your insights. They will be very
                        helpful in supporting a safer and more
                        sustainable exhibition strategy.</p>
                      <p class="MsoNormal">Best regards, </p>
                      <p class="MsoNormal"> </p>
                      <p class="MsoNormal">Marion</p>
                      <p class="MsoNormal"> </p>
                    </div>
                    <p><br>
                    </p>
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                  society whose<br>
                  mission is to improve the preservation, conservation
                  and management of<br>
                  natural history collections to ensure their continuing
                  value to<br>
                  society. See <a href="http://www.spnhc.org"
                    rel="noreferrer" target="_blank"
                    moz-do-not-send="true" class="moz-txt-link-freetext">http://www.spnhc.org</a>
                  for membership information.<br>
                  Advertising on NH-COLL-L is inappropriate.<br>
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            <br>
            _______________________________________________<br>
            NHCOLL-L is brought to you by the Society for the
            Preservation of<br>
            Natural History Collections (SPNHC), an international
            society whose<br>
            mission is to improve the preservation, conservation and
            management of<br>
            natural history collections to ensure their continuing value
            to<br>
            society. See <a href="http://www.spnhc.org"
              rel="noreferrer" target="_blank" moz-do-not-send="true"
              class="moz-txt-link-freetext">http://www.spnhc.org</a> for
            membership information.<br>
            Advertising on NH-COLL-L is inappropriate.<br>
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      <pre wrap="" class="moz-quote-pre">_______________________________________________
Nhcoll-l mailing list
<a class="moz-txt-link-abbreviated" href="mailto:Nhcoll-l@mailman.yale.edu">Nhcoll-l@mailman.yale.edu</a>
<a class="moz-txt-link-freetext" href="https://mailman.yale.edu/mailman/listinfo/nhcoll-l">https://mailman.yale.edu/mailman/listinfo/nhcoll-l</a>

_______________________________________________
NHCOLL-L is brought to you by the Society for the Preservation of
Natural History Collections (SPNHC), an international society whose
mission is to improve the preservation, conservation and management of
natural history collections to ensure their continuing value to
society. See <a class="moz-txt-link-freetext" href="http://www.spnhc.org">http://www.spnhc.org</a> for membership information.
Advertising on NH-COLL-L is inappropriate.
</pre>
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    <div class="moz-signature">-- <br>
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    <div class="moz-signature"><b>Fabian Neisskenwirth</b></div>
    <div class="moz-signature">Restaurator/Präparator</div>
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    <div class="moz-signature">Waterfohrstr. 20</div>
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            Tel: +49 (0) 1573 2778729 <br>
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