[Nhcoll-l] Refixing, Ward's solution, and other problems with old specimen

Thu Sep 10 04:43:32 EDT 2015

Thanks Dirk and Hi Jade,

You have a tricky issue here.  If your amphibians have never been in contact with formalin but you want to give them a zap of fixative, that I can understand.  The pseudo-fixation of alcohol alone is reversible and tissues can start to decay once the concentration of alcohol gets down to c. 30%.  I would suggest trying one less valuable and flabby specimen first and take it down to water, then fix and inject with formalin as per normal and then take it back up the alcohol dehydration ladder, (normally 2 hours per 10% of alcohol) until you reach your normal preservation strength.  The formalin will halt the deterioration of any tissues that are starting to decay but whether the same carbonium ion reaction will take place in a specimen that has already been in alcohol for a long time, is purely theoretical - hence the need to try with one specimen.

Ward’s solution is new to me and I checked their website but typically there is no suggestion of what is in it!  I notice that it’s used for insect specimens so it should contain alcohol but any knowledge as to its formulae would be useful.

As to Resistall: there is an acidic process apparently used in its manufacture and which can manifest itself (as Dirk suggested) if you use a large amount in a small container (likely?)  However, it is a good labelling medium and I used to keep some in a jar of alcohol, then take out a sheet or 2 prior to use and let it dry out between blotters in a small field herbarium press.  Bit time consuming but it did work.  The pH shift in the jar where the paper was stored did drop slightly over time but not enough to worry about (down to 5).  Specimens are often stored and will tolerate, slightly lower pH levels providing these don’t fall below 4.5 when decalcification of skeletons will start!  Generally I used Goatskin Parchment paper from Arjo Wiggins as this had no pH issues at all, lasted for ‘ever’ and had no ink smudging issues.

With all good wishes, Simon.

Simon Moore MIScT, RSci, FLS, ACR
Conservator of Natural Sciences and Cutlery Historian,
www.natural-history-conservation.com 

On 10 Sep 2015, at 07:51, Dirk Neumann <dirk.neumann at zsm.mwn.de> wrote:

> Dear Jade,
> 
> personally, I would refrain from injecting water-based, acidic formaldehyde solution to a specimens sitting in diluted ethanol. Especially if the specimen was weakly ethanol "fixed" in the beginning, you can't really re-fixate it by exposing it to formalin. The formaldehyde can, if at all, only preserve the current condition, but not improve it. Second, you might add a lot of osmotic issues, which could (further) damage the specimen (not to mention pH issues).
> 
> I would try to determine the current concentration of your holding fluid and would move the specimen(s) through an rising alcohol ladder (normally 20/40/60/75%). Depending on the condition of the specimen, it might be good to inject carefully a little bit ethanol inside the body cavity of specimens to support this process (not into tissues).
> 
> For any further questions centred around fluid collections, I strongly recommend John E. Simmons (2014) brilliant and exhaustive "Fluid Preservation - a comprehensive reference" (ISBN 9781442229655). Comprehensive is an understatement. It's THE REFERENCE combining knowledge since the early days of fluid preservation. If "revamping" means a taking conservative measures on a larger collection, this book might be a very valuable reference during this work. 
> 
> Regarding the paper: the potential pH shift is correlated with the fluid amount inside containers; the same paper might give a strong pH shift in a small specimen jar (< 50 ml total volume), while in a 1000 l jar the shift might be negligible. In general, also in "normal paper" you may have up to 30 different chemicals added during production that are trapped inside the paper. A possible alternative would be usage of certified archival paper. However, before you shift to another label, you should test if your printing method works with the new printing medium - not all combinations of "paper" & "printer" produce durable labels.
> 
> Hope this helps
> Dirk    
> 
> 
> Am 10.09.2015 um 03:32 schrieb Jade Keehn:
>> Greetings,
>> 
>> This year, our department is working to revamp a historic fish and herp collection in various states of disrepair. We have been diligently sifting through the curatorial literature to prepare for this process; however, there are a few things we could use some advice on. Hopefully, there are a few knowledgeable wet collection curators who can answer some questions before we begin our assessment and treatment of this valuable collection.
>> 
>> Our first question regards refixing museum specimens. A number of amphibs are in rather "soggy" condition and we are considering injecting them with 10% formalin before  returning them to ethanol solution. This 'refixing' process was mentioned in a 1978 ASIH museum practices document, but we haven't seen it discussed in anything more recent. Are there any potential disadvantages to refixing specimens to improve specimen quality/ longevity?
>> 
>> The herpetological collection is currently labeled using Resistall paper. The literature indicates that this paper type may result in an acidic/damaging pH. Is there another labeling paper that is recommended for use? 
>> 
>> A number of specimens have been preserved using Ward's solution. Are there any potential concerns or treatment procedures needed before transferring these specimens into ethanol (75%)? Secondly, is there any reason to worry about the condition of cleared and stained specimens, assuming they are still submerged in fluid?
>> 
>> Thanks in advance for the advice!
>> 
>> 
>> 
>> Jade Keehn and James Simmons
>> Assistant Museum Curators
>> Museum of Natural History
>> University of Nevada, Reno
>> 
>> 
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