Offgassing from natural history specimens

Melissa Gunter <mgunter [at] museum__vic__gov__au> writes

>I am a conservator currently researching whether or not formaldehyde
>will off-gas from freeze dried natural science specimens that have
>been injected with formalin before freezing. I am interested in
>measuring gaseous build up in enclosed spaces as well as checking if
>heat will contribute to or drive the off-gassing. I plan to run some
>tests with passive and active samplers in both ambient and heated
>environments and I wondered if anyone else has done any testing like
>this. Any information, references, comments or advice would be
>greatly appreciated.

I am surprised that specimens should require formaldehyde injection
prior to freeze-drying.  The interior workings of freeze-driers,
especially the vacuum pump, are rapidly deteriorated by formaldehyde
vapours!  I presume that the injections were carried out as part of
a bacteria-prevention exercise.

In answer to the question, the formaldehyde will off-gas and can be
detected as an aldehyde residue with test strips of paper
impregnated with Schiff or Feulgen reagent (charcoal-decolourised
basic fuchsin dye).

In short, the specimens do not require a bactericide injection but
if this is needed to prevent pest infestation there are other less
drastic methods available.

With all good wishes,

Simon Moore, MIScT, FLS, ACR,
Senior Conservator of Natural Sciences.
Hampshire County Council
Recreation and Heritage Department,
Museums and Archives Service,
Chilcomb House, Chilcomb Lane,
Winchester SO23 8RD
UK.
+44 1962 826737


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                  Conservation DistList Instance 20:45
                  Distributed: Friday, March 16, 2007
                       Message Id: cdl-20-45-007
                                  ***