[Nhcoll-l] How to transfer specimens out of an unknown preservative?

Mon Aug 23 05:25:19 EDT 2021

Just to put in my extra bit as Dirk has comprehensively covered the topic.

People often forget, when using formalin that solution for fixing should be at 10% but 5% for preserving (storing).
Translucent invertebrates such as jellies and tunicates maintain their translucency is aqueous preservatives but become opaque in alcohol, which is why so may are still stored in the former.

Distilled water can be very low in pH and unsuitable - I have measured it down to 3.5! So always ’test the waters’ before use!

With all good wishes, Simon 

Simon Moore MIScT, RSci, FLS, ACR
Conservator of Natural Sciences and Cutlery Historian,

www.natural-history-conservation.com

> On 23 Aug 2021, at 10:10, Dirk Neumann <neumann at snsb.de> wrote:
> 
> Dear Nicole,
> 
> the first articles of the first Fluid Preservation congress in Paris in 2018 published in Collection Forum are available online. Among these is Irene Finkelde's and Asher Newsome's salting-out article which is a nice an cost-efficient way to check fluids, and the article of Irene and Rob Waller to determine formaldehyde concentrations in preserving fluids.
> 
> Besides the well recognisable smell of formaldehyde, density differences between the water-based formaldehyde solution and alcohol should be easy to detect. Be aware that if you have historic specimens (pre 1900), different salts could have been used to increase the preserving strength of the alcohol. Many of these salts are not too healthy, and necessary precautions should be taken when handling such objects.   
> 
> Transfer: Not in all cases it is recommended to transfer specimens form formalin into alcohol, Paul pointed to this already. Especially some marine invertebrates like jelly fish or tunicates may suffer if they are moved from their original preservative fluid (often formalin).
> 
> You should be careful with distilled water, as this is very acidic. Tap water should be fine if there are not additives in it (e.g. chlorinated), and slow stepping with more steps (e.g. 20/40/60/75) should be preferred for delicate specimens.
> 
> Highly recommended reference and bed-lecture for all people working with fluid preserved specimens is the masterpiece John (Simmons) put together: https://www.amazon.com/Fluid-Preservation-Comprehensive-John-Simmons/dp/1442229659
> 
> It is the reference I love to consult and I am very happy to have this valuable book in reach on the shelf behind me.
> 
> Hope this helps
> Dirk
> 
> 
> 
> Am 20.08.2021 um 22:25 schrieb Nicole Seiden:
>> Hello and happy Friday!  
>> 
>> I was recently hired as a collections manager with the initial tasks of digitizing and re-opening the collections. The collections have been “ignored” for some time now and both the specimens and the database have numerous discrepancies that I’ve been addressing. Currently, I’m working with our wet-preserved specimens and want to ask the community for some advice. 
>> 
>> A large portion of our specimens (> 4,000) are preserved in an unknown fluid (listed as N/A), and many of which require topping up or rehousing to larger jars. Our most common preservative is ethanol, and it’s very likely that most are in ethanol or isopropyl, though I have had the unpleasant misfortune of opening a few preserved in formalin. 
>> 
>> Previous discussions indicated there is not a method to determine the fluid type, but is there a way to transfer the specimens into a known preservative? My initial thought is to rinse (or soak?) them in DI water and then transfer into ethanol. Does this pose any risk to the specimens (i.e., lead to damage)? Are there any precautions I should follow?  
>> 
>> 
>> Many thanks in advanced, 
>> Nicki
>> 
>> Nicki L. Seiden, M.Sc.
>> She/Her/Hers
>> Research Collection Manager
>> Harbor Branch Oceanographic Institute
>> nseiden at fau.edu
>> 
>> 
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> 
> -- 
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> 
> Dirk Neumann
> 
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> ---------
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> Dirk Neumann
> 
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> NHCOLL-L is brought to you by the Society for the Preservation of
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