>When one has a single or two specimens of an extraordinary rarity "diseases"
>usually come to mind. In some cases I keep a rare shell immersed in
>a droplet of
>oil or silicon and sealed in a vial. It is difficult to bring out
>and study and
>may take some time. However, it is the only way I feel safe with
>such specimens.
>After many years, I have seen small shells in a state of powder or totally
>coated with "salts", while in glass vials even after rinsing in
>distilled water
>and drying. This is especially so for specimens coming from Atlantic waters.
>So I am still trying out methods. I have to give liquid paraffin a try.

Bruce Marshall (National Museum of NZ) uses soda glass vials (soda
glass causes glass disease... dunno about borosilicate glass... you
lurking, Bruce?) and places the specimens within gelatine capsules in
these vials. He has no problems with glass disease, which seems to be
a reaction between calcium carbonate and the sodium in the glass.

For someone who asked, glass disease is a chemical reaction in which
specimens composed of calcium carbonate (such as molluscan shells)
stored in glass vials are attacked by chemicals in the glass. As
Constantine says above, small shells can be reduced to a sodium-based
powder. According to NZ's premier malacologist, the expensive
soda-glass vials are the bad offenders; some cheaper glass apparently
doesn't do this. Also apparently small numbers of very small
specimens stored in a vial are far more likely to be attacked than
larger specimens, or masses of smaller ones, stored in the same vial.
I guess this is merely the reaction being spread over a much larger
surface-area. I don't know whether it is possible to leach the
offending chemicals out of the glass... other than by using the
shells within to do so!

Some very small specimens (~1mm) in my collection, stored in 6x50mm
soda-glass tubes, have developed masses of radial very fine
needlelike crystals which obscure the shell entirely. Others have
cuboidal white crystals growing on them. Some have both... so there
are TWO different reactions going on in there... these shells
developed this problem in under 8 years of storage... in fact far
less.

So I have about 80,000 of these 6x50 tubes... they are absolutely
IDEAL for micros... except that they may ruin shells. I must say that
the damage to my shells occurred while they were stored at work. I
have seen NO deterioration of shells stored only at home in these
same vials, so I am not about to dispose of them. But I DO have to
check the contained specimens now and then!
--
Andrew Grebneff
165 Evans St, Dunedin 9001, New Zealand
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Seashell, Macintosh, VW/Toyota van nut