[Nhcoll-l] Alcohol concentration for terrestrial vertebrates

[John E Simmons]

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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