[Nhcoll-l] Alcohol concentration for terrestrial vertebrates

Fri May 7 11:43:32 EDT 2021

 The reference for the book is:
Simmons, John E. 2014. *Fluid Preservation: A Comprehensive Reference*.
Rowman & Littlefield. It is available from Amazon.com, from the publisher,
and other sellers.

The book includes a discussion (pp 54-56) of botanical fluid preservation
(thanks to Ann Pinzl for generously sharing with me her as yet unpublished
research on this subject). Botanists have tended to use some strange
mixtures, trying to preserve color in their specimens (particularly in
flowers).

The use of beverage alcohol as a preservative has a long and fascinating
history. Although most beverage alcohol is below 70%, it usually does a
fairly good job of preservation (proof is approximately half the alcohol
concentration, so a 20 proof spirit is about 40% ETOH). I have used
beverage alcohol to preserve when nothing else was available, and have seen
a lot of specimens preserved in it. Rum was commonly used because it was
inexpensive (things such as brandy, which usually has a higher alcohol
content than rum, actually work better).

Over the history of fluid preservation, there have been many attempts to
improve the preservative properties of alcohol. In the days before we had
an easy means to check the concentration, it was common to use alcohol
after a second distillation, which usually meant around 60-65% (depending
on the source), so such things as arsenic, mercuric chloride, and other
chemicals were commonly added to "strengthen" it (they were really just
making it a more effective biocide, but usually screwing up the specimen in
the process).

--John

John E. Simmons
Writer and Museum Consultant
Museologica
*and*
Associate Curator of Collections
Earth and Mineral Science Museum & Art Gallery
Penn State University
*and*
Investigador Asociado, Departamento de Ornitologia
Museo de Historia Natural, Universidad Nacional Mayor de San Marcos, Lima

On Fri, May 7, 2021 at 10:56 AM Mare Nazaire <mnazaire at calbg.org> wrote:

> Thank you Simon and Dirk for your feedback on this.
>
> I had actually spoken with the botanist who originally prepared the
> specimens back in the 60's - he noted that they were preserved in 50% EtOH.
> He also noted that when he had traveled to other countries for field work
> and EtOH wasn't available he would use rum! So there could be some other
> residual components in these fluid preserved specimens!
>
> On Fri, May 7, 2021 at 7:18 AM Simon Moore <couteaufin at btinternet.com>
> wrote:
>
>> Dear Mare,
>>
>> I have always fixed fresh plant material in Kew mix and then transferred
>> to Copenhagen mixture which is similar but minus the formalin.  As Dirk has
>> pointed out, the formulae (proportions) do vary slightly between
>> institutions, some prefer more glycerine in their mixes but which can make
>> the specimens rather translucent which is why others prefer a lower
>> concentration.  There is also the slight problem of osmotic pressure
>> differential and specimens floating until they equilibrate!
>> Make sure that the pH of the solutions is a near to 7.0 as possible.
>>
>> With all good wishes, Simon
>>
>> Simon Moore MIScT, RSci, FLS, ACR
>> Conservator of Natural Sciences and Cutlery Historian,
>>
>> www.natural-history-conservation.com
>>
>>
>>
>>
>> On 7 May 2021, at 13:53, Mare Nazaire <mnazaire at calbg.org> wrote:
>>
>> This is a very informative and helpful thread - thank you for this!
>>
>> I presume that 70% concentration would also be suitable for plant
>> material preserved in spirits? I ask because I've recently discovered that
>> some of our collection of fluid preserved plant material is at a
>> concentration of 50% and I wondered if it is advisable to keep them as is
>> or change their concentration to 70%. Are there recommendations in John
>> Simmon's book for preserving plant specimens in alcohol and could you also
>> provide the citation for this book?
>>
>> Thank you,
>> ~Mare
>>
>> On Fri, May 7, 2021 at 12:48 AM Erik Åhlander <Erik.Ahlander at nrm.se>
>> wrote:
>> Dear Tonya, John, Simon, Dirk - well all,
>>
>>
>>
>> Also I agree. Since I will soon retire I want to share some experiences:
>>
>> When we started to take care of the collection of wet vertebrates in
>> Stockholm in 1975 there was no overlap in time (well 1 week) with the
>> previous staff (the previous curator was employed 1934-1974). So we had to
>> invent the wheel. The initial ambition was to keep a concentration between
>> 70 and 80% ethanol. (We also tested the new suggested conservation fluid
>> Phenoxetol, which after some years showed to be a disaster). To compensate
>> for evaporation, we tried to stick to 80%. New material was fixed in
>> formalin for at least a week, washing in water, 20% ethanol for two days or
>> more, 50% for two days or more, and final storage in 80%. Also we removed
>> all bad jars from the collection – and a bad jar was a jar that needed
>> topping. Expedition material was sorted and identified etc after this stage
>> with the result that many specimens was changed to 80% once more. It took
>> more than 10 years to realize that 80% was to strong. But also that every
>> change of alcohol, or topping, resulted in a higher concentration ethanol
>> since the lowering effect of the alcohol concentration through remnants of
>> the previus stage fluid inside the specimens was removed. Also the small
>> amounts of formalin in the specimen was reduced for each change of fluid.
>> Especially for tiny fish we could find obvious shrinking. Today we are
>> careful
>>
>> 1.       To keep the specimens in 70% (not more, not less)
>>
>> 2.       Not to rinse to much in water. Rather remove the formalin from
>> the surface of the specimen only.
>>
>> 3.       Don´t change the fluid if it is not necessary.
>>
>> 4.       If you have to remove all fluid, add maybe 80-90% of fresh (70%)
>> ethanol and the rest used ethanol from another specimen.
>>
>> All formalin fixed specimens has a small amount of formalin left - that
>> is good.
>>
>> Some substances in the specimen dissolve in the alcohol (just look at an
>> alcohol preserved Anguilla…). Every change of alcohol add to the removing
>> of lipids etc - that is bad.
>>
>>
>>
>> As far as we know, formalin was used for the first time at the NRM in
>> 1904, but only occasionally! Still in the 1940s ethanol was commonly used
>> for fixation in the field. When the museum moved from downtown Stockholm to
>> north of the city in 1916, the economy for alcohol was reduced due to world
>> war I (otherwise Sweden was not involved). This led to the invention to use
>> a diluted formalin solution for the exhibition jars (for specimens fixed in
>> ethanol!). The research collection continued to be stored in ethanol. Our
>> collection is old. We estimate that our oldest specimens in ethanol are
>> from the 1720s (from the Seba collection). Still many specimens from before
>> 1758 are in remarkable good condition. In some specimens it is even
>> possible to get small pieces of DNA with ancient DNA technic – but usually
>> not. This sounds contradicting to some statements above. We don’t know too
>> much about the preservation history of these specimens, but what we know
>> might be of general interest. The initial fixation and preservation was in
>> distilled wine (=“spiritus vini”). We don’t know the concentration, and
>> probably it was not pure ethanol, but also contained small amount of other
>> fractions from the wine, more like strong cognac. The Royal collection (of
>> king Adolf Fredrik with many Linnaean types) was donated to the
>> Royal Swedish Academy of Sciences in 1801. NRM was founded in 1819, but
>> immediately in practice fused with the Academy. In 1848 the collections of
>> the Academy was formally donated to the Museum. From the 1740s to 1970 this
>> collection of  vertebrates in alcohol was moved four times. Jars and fluid
>> was probably changed twice. But most of the time the collection was stored
>> cool and dark. Glasses and fluids was expensive so the ratio: specimen
>> volume / conservation fluid volume was high up to 1900.  From 1801-1898 the
>> major part seems to have been almost untouched, except that the whole
>> collection was moved 1500 meters in 1829.
>>
>>
>>
>> I was once asked how long a specimen could be stored in alcohol. With the
>> reservation that our old specimens will be stored like today, no sudden
>> disasters etc (and no climate change), I decided that to 2220 = 500 years
>> would be possible, maybe 1000 years.
>>
>>
>>
>>
>>
>> Erik Åhlander
>>
>> vertebrate zoology and museum history
>>
>>
>>
>> ZOO
>>
>> Swedish Museum of Natural History
>>
>> PO Box 50007
>>
>> SE-10405 Stockholm
>>
>> Sweden
>>
>> +46 0 8 5195 4118
>>
>> +46 0 70 225 2716
>>
>> erik.ahlander at nrm.se
>>
>>
>>
>>
>>
>>
>>
>>
>>
>> Från: Nhcoll-l <nhcoll-l-bounces at mailman.yale.edu> För Dirk Neumann
>> Skickat: den 7 maj 2021 08:36
>> Till: nhcoll-l at mailman.yale.edu
>> Ämne: Re: [Nhcoll-l] Alcohol concentration for terrestrial vertebrates
>>
>>
>>
>> Hi Tonya (and John and Simon ;-)
>>
>>
>>
>> concur with John and Simon, specimens should be kept in 70%; Simon
>> pointed to the diluting effects and the image below nicely illustrates
>> this: even if you use more steps for transferring specimens (0/20/40/60/80
>> vs. 20/30/50/70), tissues are still soaked with 60% or less high
>> concentrated EtOH.
>>
>>
>>
>> Depending on size, body mass and number of specimens (i.e. amount of
>> tissue in the jar), the effect can be considerable (see "staining" in the
>> images below; in the left one, body fluids released from these tall
>> whitefish are indicated by the reddish haemoglobin stain at the bottom of
>> the jar, the overall greenish colour in the right comes from chlorophyll
>> released from the guts of these herbivorous distichodus fish).
>>
>>
>>
>> I do the initial filling usually with 73-75% EtOH to reach 70%; aside
>> from vertebrates high EtOH concentrations can be an issue in malaise traps
>> because there the specimens usually are collected over several days or
>> weeks in 96-80% EtOH. As Simon pointed out this quickly dehydrates
>> specimens and weakens the joints holding all the antennae, appendices,
>> bristles of invertebrates. Another issue is that in unsorted malaise trap
>> samples there often is a thick deposit of specimens at the bottom of the
>> container. Because the diluted less high concentrated ethanol is heavier,
>> it layers at the bottom of the jar (cf. whitefish jar). Inside malaise trap
>> containers, this diluted EtOH may get trapped in the thick specimen deposit.
>>
>>
>>
>> Usually, I leave jars for few day to see if there are any unwanted
>> effects before moving them into the collection.
>>
>>
>>
>> Hope this is useful, with best wishes
>>
>> Dirk
>>
>>
>>
>>
>>
>>
>>
>> <image001.png>
>>
>>
>>
>> Am 07.05.2021 um 00:17 schrieb Simon Moore:
>>
>> Thanks John and Tonya,
>>
>>
>>
>> What John says is true about the staging of alcohols and the final
>> concentrations.  80% was what I was advised at the NHM in London when I
>> worked there and by the time larger terrestrial vertebrates ‘end up’ in
>> 80%, you will often find that with the mix of lower grade alcohols from the
>> staging process, once things have settled down / equilibrated, then the net
>> result is around 70% anyway.  Higher grade alcohols  can lead to
>> embrittlement of certain tissues as well as evaporation issues.
>>
>>
>>
>> I have also found the staging process necessary for the more fragile
>> specimens as they undergo changes in Osmotic pressure during this process
>> which can cause syneresis or shrinkage in softer tissues.
>>
>>
>>
>> With all good wishes, Simon
>>
>> Simon Moore MIScT, RSci, FLS, ACR
>> Conservator of Natural Sciences and Cutlery Historian,
>>
>> www.natural-history-conservation.com
>>
>>
>> <image002.jpg>
>>
>>
>>
>>
>> On 6 May 2021, at 22:50, John E Simmons <simmons.johne at gmail.com> wrote:
>>
>> Tonya,
>> Thank you for your kind words about my book. The recommendation for
>> staging up to 80% concentration was by made by my friend Simon Moore, who I
>> cited in that sentence. In general, I do not recommend using 80% ETOH as a
>> preservative for terrestrial vertebrates, but rather 70%. Preservation is
>> alcohol is a trade-off between dehydration of the specimens and providing
>> them suitable protection against biological deterioration. At 70%, ETOH is
>> a very good biocide; below that, not so good, and above 70%, too strong for
>> most specimens (note that there are some instances in which 80% might be
>> preferred).
>>
>> I do not recommend using stronger alcohol as a hedge against
>> evaporation--that leads to uneven concentrations of preservatives and can
>> be a real mess to work with in a collection.
>>
>> For how-to instructions on preserving, transferring specimens, and
>> managing a fluid preserved collection, you might want to check
>> Herpetological Collecting and Collections Management (3rd edition, 2015).
>> The instructions for preserving and managing fluid preserved animals will
>> work for most other specimens as well as for reptiles and amphibians.
>>
>> Hope this helps,
>> --John
>>
>> John E. Simmons
>> Writer and Museum Consultant
>> Museologica
>> and
>> Associate Curator of Collections
>> Earth and Mineral Science Museum & Art Gallery
>> Penn State University
>> and
>> Investigador Asociado, Departamento de Ornitologia
>> Museo de Historia Natural, Universidad Nacional Mayor de San Marcos, Lima
>>
>>
>> On Thu, May 6, 2021 at 4:05 PM Haff, Tonya (NCMI, Crace)
>> <Tonya.Haff at csiro.au> wrote:
>> Hello all,
>>
>> I am enjoying reading John Simmon's fantastic book on fluid preservation.
>> In it I read one suggestion for stepping specimens up out of formalin
>> fixative into preservation alcohol as follows: from 20% ETOH to 40% to 60%
>> and finally to 80%. We typically place our specimens in 70% ETOH, and I
>> know higher concentrations can cause some problems with specimen
>> dehydration. All our specimens are terrestrial vertebrates. I presume the
>> final 80% provides a buffer against ETOH evaporation or leaching of water
>> from the specimen into the fluid in the jar, to ensure that the alcohol
>> concentration in the preservation fluid stays sufficiently high? But to me
>> this is not quite clear. I wonder if any of you have thoughts on this, or
>> if you would be willing to share how you step your specimens up in ETOH?
>>
>> Thank you!
>>
>> Tonya
>>
>>
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>> _______________________________________________
>> 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 http://www.spnhc.org for membership information.
>> Advertising on NH-COLL-L is inappropriate.
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>> --
>>
>> <image004.png>
>>
>>
>> Dirk Neumann
>>
>> Tel: 089 / 8107-111
>> Fax: 089 / 8107-300
>> neumann(a)snsb.de
>>
>> Postanschrift:
>>
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>> Münchhausenstr. 21
>> 81247 München
>>
>> Besuchen Sie unsere Sammlung:
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>>
>> ---------
>>
>> Dirk Neumann
>>
>> Tel: +49-89-8107-111
>> Fax: +49-89-8107-300
>> neumann(a)snsb.de
>>
>> postal address:
>>
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>> Muenchhausenstr. 21
>> 81247 Munich (Germany)
>>
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>>
>> _______________________________________________
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>>
>> _______________________________________________
>> 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 http://www.spnhc.org for membership information.
>> Advertising on NH-COLL-L is inappropriate.
>>
>>
>> --
>> Mare Nazaire, Ph.D.
>> Administrative Curator, Herbarium [RSA-POM]
>> California Botanic Garden
>> Research Assistant Professor, Claremont Graduate University
>> 1500 North College Avenue
>> Claremont, California 91711
>> 909.625.8767 ext. 268
>> _______________________________________________
>> Nhcoll-l mailing list
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>>
>> _______________________________________________
>> 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 http://www.spnhc.org for membership information.
>> Advertising on NH-COLL-L is inappropriate.
>>
>>
>>
>
> --
> Mare Nazaire, Ph.D.
> Administrative Curator, Herbarium [RSA-POM]
> California Botanic Garden
> Research Assistant Professor, Claremont Graduate University
> 1500 North College Avenue
> Claremont, California 91711
> 909.625.8767 ext. 268
> _______________________________________________
> Nhcoll-l mailing list
> Nhcoll-l at mailman.yale.edu
> https://mailman.yale.edu/mailman/listinfo/nhcoll-l
>
> _______________________________________________
> 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 http://www.spnhc.org for membership information.
> Advertising on NH-COLL-L is inappropriate.
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