[Nhcoll-l] Alcohol concentration for terrestrial vertebrates

Fri May 7 08:53:04 EDT 2021

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
>
>
>
>
>
>
>
>
>
> 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
> <https://url11.mailanyone.net/v1/?m=1leu5X-0006gs-5g&i=57e1b682&c=P_JTOxhc00RtGTsMjTrryrRBThMnzI5k1ol2aDVqPITm0G_xR0drpuNIhh-krJ6ihFhOLJnXYNjI5fJDeS7rag0t-LwIYs0jmRWXIk2uN2sYVvoo4O9RHPsKEAKiAK-LvbrlH-pnEJMM5dJlJOlNvswIXfaiFJxHBKwsoJX5uQ31zmivYbvBNJdb61ZNkqDKGinISZmQBmu6t6VBola0IT4zHh0nqkiHmWvI7KCXEbWncO8-owQTcerGpMed6sP9>
>
>
>
>
> 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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> --
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>
> Dirk Neumann
>
> Tel: 089 / 8107-111
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>
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>
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> ---------
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>
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>
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-- 
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
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