[NHCOLL-L:5144] RE: white crystals appearing on specimens in fluid, any ideas?

Fri Dec 17 06:05:58 EST 2010

Dear Heather,

It is probably the same process that is causing efflorescence on oil
paintings. There are 3 stages: free fatty acid migration, exudation, and
crystallization. Although the mechanism is not exactly clear, the
oxidation and hydrolysis of triglycerides (fats) play a major role.
Metal ions such as ferro and copper will accelerate the process.  

Regards,

Dries

Andries J. van Dam, conservator

Museum of Anatomy
Leiden University Medical Center 
Postal zone T7-P
P.O. Box 9600 
2300 RC Leiden 
The Netherlands 
tel: +31 (0)71 526 9581
fax: +31 (0)71 526 8275 
E-mail: A.J.van_Dam at lumc.nl
Visiting address: Hippocratespad 21, building 3

Associate scientist, Natural History Museum, London
http://www.nhm.ac.uk

Directory Board member ICOM-CC
http://www.icom-cc.org 

Director Alcomon Company
http://www.alcomon.com 

-----Original Message-----
From: owner-nhcoll-l at lists.yale.edu
[mailto:owner-nhcoll-l at lists.yale.edu] On Behalf Of Heather Campbell
Sent: donderdag 16 december 2010 21:21
To: NHCOLL-L at lists.yale.edu
Subject: [NHCOLL-L:5137] white crystals appearing on specimens in fluid,
any ideas?

Hello all,

While rehousing the bee wet collection I have noticed that some vials
contain specimens that have white material growing (?) on them.  Here
are
a few details that may be important when considering a diagnosis:
1. Only vials containing larvae (maybe pupae) are affected
2. Different species and different years (but always older than 5yrs)
and
different locals
3. Preservative used: Kahle's sol
                       acetic acid (glacial) 10%
                       formalin (37%)        10%
                       water                 25%
                       Ethanol (75%)         55%
4. Easily scraped away and has a plaque-like resemblance
5. no visible damage done to specimen (naked eye)

I have pictures but am unable to send due to limits on message size.  I
will be happy to send these along to anyone who is interested.

Thank you

Heather M. Campbell
Bee Curatorial Assistant
Division of Invertebrate Zoology
American Museum of Natural History
Central Park West @ 79th st.
New York, NY 10024-5192
212-496-3447