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<p>Hi Tonya,<br>we have been using this method for over 10 years with very good results.<br>A physicist told me that lower temperatures (-30 °C) are better than -20 °C, as smaller ice crystals form here.<br>Above all, it is more effective against collection pests.<br>We freeze the objects at -32 °C for at least a week.</p>
The problem is not actually the freezing, but the thawing.</div>
<div>However, condensation forms during thawing, which could damage the objects. It is therefore best to wrap the specimens as tightly as possible in foil, trapping as little air as possible. This should minimize the amount of moisture in the air that condenses during thawing.<br>Condensation can attack the wires inside or soften the objects a little or damage the ink on old labels.
<p>It is not necessary to wrap insect-drawers separately in foil (in my opinion!). I have carried out tests and found that the wooden boxes buffer the fluctuations in humidity very well.</p>
<p>However, it is important to remove the objects carefully from the freezer (especially delicate insects) and leave them to thaw in peace, as the frozen structures are fragile and can be damaged by vibrations.</p>
<p>Good luck<br>Joachim</p>
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<div><span style="color: #949494; font-family: Arial, sans-serif; font-size: small;">Joachim Haendel</span></div>
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<div><span style="color: #949494; font-family: Arial, sans-serif; font-size: small;">Center of Natural History Collections<br>of the Martin Luther University (ZNS)<br>- Entomological Collection -<br><br>Domplatz 4<br>D-06099 Halle (Saale)<br>Germany<br><br>Phone: +49 345 - 55 26 447<br></span><span style="color: #949494; font-family: Arial, sans-serif; font-size: small;">Email: joachim.haendel@zns.uni-halle.de</span></div>
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<div id="GroupWiseSection_1709189596936_Joachim.Haendel@zns.uni-halle.de_659232D005F00000BEC929790EDC4731_" class="GroupWiseMessageBody"><span class="GroupwiseReplyHeader"><br>>>> "Haff, Tonya (NCMI, Crace)" <Tonya.Haff@csiro.au> 29.02.2024, 06:53 >>><br></span>
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<p class="MsoNormal">Hello all,</p>
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<p class="MsoNormal">I am wondering if any of you can give me feedback how your specimens have responded to low temperature treatment for pests. Specifically, I’m interested in what types of specimens you’ve used low temperature on (freezing), at what temperatures, and if you’ve observed any negative effects on your specimens as a result of colder temperatures? I’m especially interested if any of you all use temperatures between -30 and -40C, and whether or not you’ve noticed any effect on your specimens, relative to say -20C. We are trying to optimise our pest treatment while mitigating risk to our dry specimens, which include pinned insects, study skins, and bones. We will be using refrigerated shipping containers to do this work, which will be on large numbers of specimens at a time. I think we understand the parameters, but I would be very interested to hear especially about direct experience, caveats, things to watch out for, etc.</p>
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<p class="MsoNormal">Thanks so much!</p>
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<p class="MsoNormal">Tonya</p>
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<p class="MsoNormal"><span style="mso-fareast-language: EN-AU;">-------------------------------------------------</span></p>
<p class="MsoNormal"><span style="mso-fareast-language: EN-AU;">Dr. Tonya M. Haff</span></p>
<p class="MsoNormal"><span style="mso-fareast-language: EN-AU;">Collection Manager</span></p>
<p class="MsoNormal"><span style="mso-fareast-language: EN-AU;">Australian National Wildlife Collection</span></p>
<p class="MsoNormal"><span style="mso-fareast-language: EN-AU;">CSIRO</span></p>
<p class="MsoNormal"><span style="mso-fareast-language: EN-AU;">+61(0)419569109</span></p>
<p class="MsoNormal"><span style="mso-fareast-language: EN-AU;"><a href="https://www.csiro.au/en/about/facilities-collections/collections/anwc">https://www.csiro.au/en/about/facilities-collections/collections/anwc</a></span></p>
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