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<p>I rest my case...</p>
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<p>--Dries<br>
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<div id="divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" style="font-size:11pt" color="#000000"><b>Van:</b> Nhcoll-l <nhcoll-l-bounces@mailman.yale.edu> namens John E Simmons <simmons.johne@gmail.com><br>
<b>Verzonden:</b> zondag 18 september 2022 20:09:59<br>
<b>Aan:</b> Maxine C<br>
<b>CC:</b> NHCOLL-new<br>
<b>Onderwerp:</b> [MOGELIJK SPAM ! *****] Re: [Nhcoll-l] Preserve fish specimens</font>
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<div class="gmail_default" style="font-family:tahoma,sans-serif;font-size:small;color:#000000">
I agree with Dirk--it is not possible to preserve the colors found in living fish (or any other organism) by preseCorvation in fluid preservatives. There are several factors to consider, including:</div>
<div class="gmail_default" style="font-family:tahoma,sans-serif;font-size:small;color:#000000">
1-Color comes from a combination of pigments (many of which are photosensitive or subject to alteration by the fixatives or preservatives) and the reflection and refraction of light, so that any shrinkage or swelling is likely to alter color even if the pigments
are not affected.</div>
<div class="gmail_default" style="font-family:tahoma,sans-serif;font-size:small;color:#000000">
2-In most organisms, color is not stable. Some colors are temporal (depending on the time of year), affected by the environment, the age of the organism, or the time of life of the organism (for example, colors that show only during mating season).</div>
<div class="gmail_default" style="font-family:tahoma,sans-serif;font-size:small;color:#000000">
3-The perception of color of an organism by a human being may be very different from how the color is seen by other species.</div>
<div class="gmail_default" style="font-family:tahoma,sans-serif;font-size:small;color:#000000">
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<div class="gmail_default" style="font-family:tahoma,sans-serif;font-size:small;color:#000000">
Over the last 200 years, there have been dozens of recipes published for the preservation of color or restoration of color in preserved tissues. The one element linking all of these publications is that very few of them used an accurate color reference standard.
Instead, a researcher would look at the specimen weeks or months after preservation and pronounce its colors to be lifelike without reference to what the colors were at the moment of preservation. Without a color reference, it is impossible to look at a specimen
and claim that its colors have not changed. I reviewed several of these recipes in my book,
<i>Fluid Preservation: A Comprehensive Reference</i> (<span style="font-size:11pt;line-height:107%;font-family:"Calibri",sans-serif"><a href="https://www.amazon.com/Fluid-Preservation-Comprehensive-John-Simmons/dp/1442229659" style="color:rgb(5,99,193);text-decoration:underline">https://www.amazon.com/Fluid-Preservation-Comprehensive-John-Simmons/dp/1442229659</a></span>).</div>
<div class="gmail_default" style="font-family:tahoma,sans-serif;font-size:small;color:#000000">
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<div class="gmail_default" style="font-family:tahoma,sans-serif;font-size:small;color:#000000">
It is not possible to avoid swelling and shrinkage of specimens during preservation, either, but it can be minimized. The dimensional changes that an organism goes through during fixation and preservation are highly variable, even within a species (I reviewed
the literature on dimensional changes during fixation and preservation in the above mentioned book as well). Dimensional changes result not only from the fixative and preservative chemicals used, but also how the specimens are handled, euthanized, the time
interval between death and fixation or preservation, and the light exposure that a specimen is subjected to during the process of preservation.<br>
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<div class="gmail_default" style="font-family:tahoma,sans-serif;font-size:small;color:#000000">
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<div class="gmail_default" style="font-family:tahoma,sans-serif;font-size:small;color:#000000">
There are a few things you can do during preservation that will keep the change of color as well as dimensional changes at a minimum (but you cannot save the actual colors of the organism at the time of its death, and specimens will undergo body mass changes
during preservation):</div>
<div class="gmail_default" style="font-family:tahoma,sans-serif;font-size:small;color:#000000">
1. Keep the specimen in the dark as much as possible (particularly away from sunlight, which is rich in ultraviolet radiation), both during fixation and subsequent preservation.
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<div class="gmail_default" style="font-family:tahoma,sans-serif;font-size:small;color:#000000">
2. Minimize the length of time the specimen is kept in a formaldehyde-based fixative (depending on the specimen size and surface-to-volume ratio, this may mean a few hours or a few days).<br>
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<div class="gmail_default" style="font-family:tahoma,sans-serif;font-size:small;color:#000000">
3. Keep the specimen at cool (but not cold) temperatures (heat accelerates the chemical processes that cause color changes).</div>
<div class="gmail_default" style="font-family:tahoma,sans-serif;font-size:small;color:#000000">
4. Stage specimens through concentration steps of about 20% each as you move the specimen from the formaldehyde-based fixative to an alcohol-based preservative.</div>
<div class="gmail_default" style="font-family:tahoma,sans-serif;font-size:small;color:#000000">
5. Prepare fixative and preservative fluids using the cleanest water possible (ideally, deionized water). Do not use denatured alcohol. There is no evidence from controlled studies to indicate that glycerine will preserve colors any better than ethyl alcohol,
and there are too many uncontrolled variables to make that assumption based on examination of specimens post-preservation.<br>
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<div class="gmail_default" style="font-family:tahoma,sans-serif;font-size:small;color:#000000">
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<div class="gmail_default" style="font-family:tahoma,sans-serif;font-size:small;color:#000000">
The only way to preserve an accurate record of the colors of an organism at the moment of its death is to take photographs. However, there are many variables that can affect color rendition in photographs as well, such as light intensity, light color, and the
equipment you use. To be able to correct for these factors later, always include a color scale in the photograph. It is not possible to make accurate color corrections in images (whether analog or digital) without having a scale in the original photograph.
There are many color scales you can get for use in the field, such as this one: <span style="font-size:11pt;line-height:107%;font-family:"Calibri",sans-serif">
<a href="https://www.bhphotovideo.com/c/product/714596-REG/Tiffen_EK1527654T_Q_13_Color_Separation_Guide.html/?ap=y&ap=y&smp=y&smp=y&lsft=BI%3A6879&gclid=CjwKCAjwg5uZBhATEiwAhhRLHsmNShKFUMn2utxapxXxbKQCGo_o1z68Xqmr2tMnLTxSDW6AJrX9LxoCcBoQAvD_BwE" style="color:rgb(5,99,193);text-decoration:underline">https://www.bhphotovideo.com/c/product/714596-REG/Tiffen_EK1527654T_Q_13_Color_Separation_Guide.html/?ap=y&ap=y&smp=y&smp=y&lsft=BI%3A6879&gclid=CjwKCAjwg5uZBhATEiwAhhRLHsmNShKFUMn2utxapxXxbKQCGo_o1z68Xqmr2tMnLTxSDW6AJrX9LxoCcBoQAvD_BwE</a></span>
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<div class="gmail_default" style="font-family:tahoma,sans-serif;font-size:small;color:#000000">
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<div class="gmail_default" style="font-family:tahoma,sans-serif;font-size:small;color:#000000">
--John</div>
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<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>
Associate Curator of Collections<br>
Earth and Mineral Science Museum & Art Gallery<br>
Penn State University<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>
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<div dir="ltr" class="gmail_attr">On Fri, Sep 16, 2022 at 7:44 AM Maxine C <<a href="mailto:cutraccimaxine@gmail.com">cutraccimaxine@gmail.com</a>> wrote:<br>
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<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">Hi all,
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<div>I'm working on a research project at the University of Hong Kong on fish biodiversity. We would like to preserve very small cryptobenthic fish species ( 5 - 10 mm in length). </div>
<div>In the past, I've used formalin and ethanol 70% but I'd like to preserve the coloration.</div>
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<div>Any advice? Would resin work?</div>
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<div>Regards,</div>
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<div>Maxine </div>
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