Hi Tammy,

As Simon has mentioned the 'preserving fluid' could well be one of the Kaiserling or Wentworth formulations which attempt to colour. However some of the generic commercial formulations of preserving fluid are also based around Steedmans formulation (which is basically phenoxetol). There are pros and cons with all of these, plus any colour preservation is only short term, plus from a museum perspective phenoxetol is not regarded as a long term preservative. The other 'standard' is 4% buffered formaldehyde.

Another consideration avoiding the various issues around ethanol based preservation is the use of DMDM-Hydantoin (which is available under a number of trade names such as Dekafald from Jan Dekker international). This is a 'formaldehyde releaser' used to replace formaldehyde in cosmetics etc. Whilst still effectively an aldehyde fixative, the active levels of formaldehyde are very low making it much more pleasant to work with than formaldehyde itself, plus the pH tends to remain more neutral. Dries van Dam has done quite a bit of research into DMDMH, and I have been using it for a number of years especially with fish specimens as it makes a viable display medium to use fluid preserved specimens in exhibitions. So the plus points are growing evidence of DMDMH as an effective preservative (although its only been considered over the last 10-15years), the negative points are that its very expensive to buy in small quantities. If you go for this then its used as a 10% solution from the stock solution supplied (which is 55% DMDMH).

As to preserving your sharks - well in summary;

First challenge - find a jar big enough. Next challenge is to select your preserving medium.... Then carefully defrost prior to preserving. The sharks will be too thick to just stick in solution so you'll need to infuse the specimens with the preserving medium otherwise they can potentially still decay in the middle. Best way is to inject into the muscle tissue and body cavities. This is particularly important with fixatives such as the aldehydes as they will fix the outer layers preventing movement of the preservative/fixative into the deeper tissues. Move to jar and add preserving medium. Stand back and admire!

Contact me off list if you want to discuss further,

Best wishes

Jules

Julian Carter
Amgueddfa Cymru-National Museum Wales





________________________________
From: The Natural Science Collections Association discussion list [[log in to unmask]] On Behalf Of Simon Moore [[log in to unmask]]
Sent: 23 February 2015 15:22
To: [log in to unmask]
Subject: Re: Best way to preserve small shark specimens

Hi Tammy,

Re this ‘preserving fluid’ you have, do you have any idea what it comprises, also does it have a vinegary smell by any chance?  The latter may be Kaiserling’s preservative. But there is also Wentworth’s colour preserving technique.

Ideally, frozen specimens should go into some formalin-based fixative first

With all good wishes, Simon.

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




On 23 Feb 2015, at 15:02, Horton, Tammy <[log in to unmask]<mailto:[log in to unmask]>> wrote:

Dear all,

I am hoping for some advice.  A colleague has some frozen specimens of small deep-sea sharks.  We would like to make these available for use in teaching and therefore have decided they would be best moved to jars of preservative fluids.  In the past I know we have used a solution called 'preserving fluid' which allows us to retain the dark colouration in such specimens (avoids the bleaching effect that ethanol has).  However I wonder if there are any other techniques we should consider?  Do I need to do anything other than defrost the specimens and move into the preserving fluid?

Thanks for any advice.

Tammy


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