[NHCOLL-L:4390] RE: plants, liquid preservation and colours

[Moore, Simon]

Hi Maria,

The problem with many of these fluid fixatives and preservatives is that
the specimens are still UV-sensitive once preserved.  There are some
fluids that can 'keep' chlorophyll-based colours but more by
susbstitution with copper salts (copper acetate) so that the chlorophyll
has a bluish tinge.  
There are various approaches - anoxic fluids such as liquid paraffin
which supposedly seals the specimen away from bacteria, and prevents
breakdown.  I have not tried this and would suggest fixing for 24 hours
(in the dark) in Kew Mix first before transferring (via a thorough water
rinse to get rid of any fixation chemicals) to liquid paraffin which, as
you may know, is a clear slightly viscous liquid.  Glyercol may be
another storage fluid option (but has very slightly acidic properties)
or even propylene glycol but some experimentation will have to be done
(how much time do you have?)
I have also listed some alternative techniques on p. 131 in Care &
Conservation of Natural History Collections (eds. Carter & Walker).  If
you cannot get hold of a copy, let me know although most of these came
from  Wagstaffe & Fidler: The preservation of Natural History Specimens,
vol. 2.  Witherby, London 1968.

As you may know, chlorophyll is a tetrapyrrole structure centred with
magnesium attached by some rather 'fragile' bonding. Most fluids remove
the magnesium from the chlorophyll so that the molecular structure
changes and it loses its colour.

Hope that this helps.


With all good wishes, 
Simon Moore, MIScT, FLS, ACR,
Senior Conservator of Natural Sciences. 
Hampshire County Council,
Department of Culture, Communities and Rural Affairs,
Museums & Archives Service,
Chilcomb House, Chilcomb Lane,
Winchester SO23 8RD. UK.
Internal  8 327 6737
01962 826737
http://www.hants.gov.uk/museum/biology 



-----Original Message-----
From: owner-nhcoll-l at lists.yale.edu
[mailto:owner-nhcoll-l at lists.yale.edu] On Behalf Of Maria Chiara
Deflorian
Sent: 15 July 2009 09:07
To: NHCOLL-L at lists.yale.edu
Subject: [NHCOLL-L:4389] plants, liquid preservation and colours


For our new permanent exhibition we will show some liquid preserved
botanical specimens, that we haven't prepared yet. The specimens at
issue are cauliflowers and cabbages. Some time ago we did a test with
the 'Kew mix' (http://www.kew.org/collections/spiritcol.html), but the
plants lost their colour. Did we make any mistakes?

Have anyone suggestions how to preserve colours with a simple procedure?

Thank you
Maria Chiara
_______________________________
dott.ssa Maria Chiara Deflorian
Museo Tridentino di Scienze Naturali
Via Calepina, 14
38100 Trento
Tel. 0461 270340
Fax 0461 207376
e-mail: deflorian at mtsn.tn.it


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