[Nhcoll-l] Fluid preservation: what is Triple Fix?

[John E Simmons]

Simon Moore can correct me if I am wrong, but my guess is that the “triple
fix” refers to what was commonly known as FAA, an attempt to make a
“universal fixative” or a “universal killing and fixing agent.”



There were many variations of the formula promoted by botanists and
zoologists, each involving differing amounts of formaldehyde, acetic acid,
and alcohol. The idea was that you could use this solution to fix and
preserve tissues at the same time in the field, and some authors even
recommended using it as a long-term fixative. However, Dempster (1960:69)
cautioned that chemically, it does not work, because “the fixing reagents
in a mixture do not penetrate the tissue *en masse*, but… each reagent
penetrates tissue in a characteristic sequence.” FAA was mentioned in at
least one edition of the Kew *The Herbarium Handbook* with the warning that
it “makes specimens brittle” (Forman and Bridson 1989:72)



The exact formulas varied from one author to another. A fairly typical
mixture was 6.5 cc formaldehyde, 2.5 cc glacial acetic acid, and 100 cc of
50% alcohol; another version of FAA was 90 parts ethanol, 5 parts glacial
acetic acid, and 5 parts formalin. In the UK, it was typically
formaldehyde, industrial methylated spirit (which is a form of denatured
ethanol), and acetic acid.



I have listed as many variations of the formula as I could find in Table 1
of *Fluid Preservation: A Comprehensive Reference* (2014), along with a
reference to their publication.



[Dempster, W. T. 1960. Rates of penetration of fixing fluids. *American
Journal of Anatomy, *107:59–72]


--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, Jan 20, 2023 at 11:13 AM Claire Smith <c.e.smith at pgr.reading.ac.uk>
wrote:

> Hi everyone,
>
> One of our students has come across a fluid specimen in our teaching
> collection that is preserved in “Triple Fix” – does anybody know what that
> is?
>
>
>
> Many thanks for your help,
>
> Claire
>
>
>
> *******
>
> *Claire Smith *(she/her)
>
> *Graduate Teaching Assistant & PhD Candidate, Cole Museum of Zoology*
> c.e.smith at pgr.reading.ac.uk
> claire.smith at reading.ac.uk
> www.twitter.com/wetconservatrix
>
>
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