[Nhcoll-l] Algae in jars - to refill or not to refill

[Simon Moore]

Hi Gali,

Your problem has given rise to several options. 

 If the specimens are still flexible enough to mounts onto herbarium sheets…?
Secondly, if you wish to keep them fluid-preserved then fine but you may need to rehydrate the dried-out specimens, I still use 5% Decon-90 glassware surfactant, gently warmed until they have their natural flex once again; it will only take about 30 minutes but holdfasts may take a while longer.
Thirdly, if you replace them into alcohol then any residual chlorophyll pigments will be denatured in that fluid.  If they were preserved in formalin, that should be a 5% solution only rather than the usual fixative strength of 10%.
Fourthly, if there are salt crystals present in the dried-out specimens, then the full-strength formalin (37.65% formaldehyde) will have been diluted using sea-water. Bear that in mind as well.

Hoping that this helps.

With all good wishes, Simon.

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



www.natural-history-conservation.com 




> On 29 Jul 2020, at 08:02, Gali Beiner <gali.beiner at mail.huji.ac.il> wrote:
> 
> Dear All, 
> 
> We have a group of jars containing algae, apparently collected in the 1970s. Some of the jars still hold a little liquid but most of the solvent has gone and quite a few jars are now completely dried out. 
> 
> ... In addition, it isn't absolutely certain what the solvent was - possibly formalin. I've been asked whether it would be OK to refill the jars with 70% ethanol. Can anyone here give advice relating to algae within this context?
> 
> Thank you, 
> Gali
> 
> -- 
> Gali Beiner (ACR)
> Conservator, Palaeontology Lab
> National Natural History Collections
> The Hebrew University of Jerusalem 
> Berman Building, Edmond J. Safra campus, Givat Ram
> Jerusalem 91904, Israel
> Fax. 972-2-6585785
> gali.beiner at mail.huji.ac.il
> https://nnhc.huji.ac.il/?lang=en
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