slide restoration

[Luis C. Muniz]

Dear Birger,


Reading your message, I understood all of the problems, because I work in
curatorship too (helminthological). I have here in Brazil, a Collection of
slides (near 10,000) from the begining of this century (plus 25,000 most
recent).=20
I think that one of the major problem related to this is the temperature
and humidity of the local where the Collection is situated. Now we are
operating with   a controlled temperature and humidity of the air.

Regarding to the problems stated in your message, I can contribute saying
that all of our old slides are mounted in Canada Balsam (very important to
be natural, not synthetic) and the borders of the coverslip with sealing
wax (not used nowadays).

A very dificult operation is unmount the slide. I have disgusting results,
specially when the mounting medium (Balsam) is completely dried, because
the solvent used acts on the specimens too, making them unclear and not
diafanized.

Other serious problem is that, a mounting media called entellan (a
synthetic medium produced by Merck) are used to mount slides (specially
arthropod-like animals), and I have the experience that passing 2 years,
the slides begining to show white precipitations inside (similar of your
problem) and the preparation seems like to broke in a small fragments
inside. Could your slides be mounted with a kind of synthetic balsam in
1900=B4s ?

I suggest that if it is possible, you can mount again the fragments (I know
with the precision of a surgeon) with a natural balsam, to try to preserve
the remaining specimens.

I strongly recommend do not to try to use any kind of solvent, like Xylene
or Creosote, in order to prevent to dammage the specimens.

I hope that I could contribute in some way.
Keep in contact,

Luis



=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D
Dr Luis C. Muniz
Substitute Curator - Helminthological collection
FIOCRUZ
Dept. Helmintologia
Lab. Helmintos Parasitos de Vertebrados
Av. Brasil 4365
Rio de Janeiro - RJ
CEP 21045-900
BRASIL



>reviewing my slide collection of "worms" up to 150 years old I realized
>that an increasing number of slides suffers from different problems:
>
>1. The coverslips of slides some 50-100 years old have disconnected from
>the embedded whole mount. Is somebody aware what kind of embedding medium
>was used commonly at that time in Germany, Europe, or the USA? Is it
>possible to identify the embedding medium in one way or another easily?
>2. The embedding medium (might be canada balsam) has withdrawn from around
>the specimen leaving the specimen in a cavity. Is there any possibility to
>re-embed specimens?
>3. Slides from the rotifer collection of Charles Rousselet (slides made
>around 1910) show white precipitations in the periphery of the sealed
>coverslip. The embedding medium is glass-clear and not yellowish as in
>other material from that time.
>4. Slides occasionally break apart, and we try to glue together major parts
>with a glass-clear 2-component epoxid resin (Henkel: Pattex Kraft-Mix).
>5. Which embedding medium/procedure would you recommend for permanent
>slides of fresh specimens of a) Crustacea and b) "worms" such as Polychaeta
>or Nematoda? Sealed paraffin-glycerin mounts as commonly used for nematodes
>probably require regular inspection intervals o check the quality of the
>slides?
>
>I have looked through several books on the preservation of natural history
>collections, but did not find hints to how to solve problems as mentioned
>above. I would greatly appreciate your comments, suggestions, hints to
>published references, ...
>
>Birger
>
>------------------------------------
>Dr. Birger Neuhaus
>Museum fuer Naturkunde
>Institut fuer Systematische Zoologie
>Invalidenstr. 43
>D-10115 Berlin
>Germany
>Tel.: +49 (0)30 2093 8525
>Fax: +49 (0)30 2093 8528
>e-mail: birger=3Dneuhaus at museum.hu-berlin.de
>
>