I use paraffin on my shells. It is a perfectly colorless scent-free oil
which never goes off. I wonder if it can be thinned with lighter fluid?

Alternative to lighter fluid would be any light organic solvent that
evaporates entirely and is miscible with the oil being used. Acetone,
"white spirits" or white gas, even ethanol.

Once, 23 years ago, I used vegetable cooking oil on a few specimens.
Eventually they became slightly tacky. Not a good idea. I suspect that,
left long enough, such oil would congeal into an irremovable varnish.

A friend in Florida was using glycerine on her shells. It seems the
glycerine isn't absorbed well by the shell. But of course it can be washed
off with water.

I DO use glycerine on opercula and periostracum (great for keeping hairy
capulid and ranellid periostracum soft and pliable). Mixed with ethanol or
formalin, chitons can be soaked in it and then dried. They remain soft and
don't shrivel. Be aware however that ethanol doesn't denature proteins, and
they may still rot once the ethanol evaporates. An animal soaked in
formalin will never rot, providing that the chemical has soaked right
through the tissues. But don't leave them too long in formalin mixed to the
recommended 4%; it will begin to etch shells left in it for more than a few
days (commercial formalin is an aqueous solution of formaldehyde at a fixed
percentage; pretend that it is at 100% and dilute to 4%. That is, mix every
milliliter of commercial formalin with 24ml water).

I can think of 2 problems with using oily substances on shells: 1) If
writing numbers on them (preferably with a Faber Castell or Rotring
drafting pen and permanent Rotring drawing ink), do so BEFORE oiling. You
won't be able to write on an oiled shell. I'm not sure, but oils may soften
any ink used. 2) Shells develop microfractures. Those boiled or frozen
inevitably become thermally stressed, and this produces cracks. Oil will
penetrate these cracks and if the affected bit ever breaks off you will
need to thoroughly degrease the specimen and fragment(s) before repairing.
Satellite City HS-T (gapfilling or thick) superglue is an excellent
repairer, especially when combined with Satellite City accelerator
(catalyst). Some may be revolted by the idea of glued shells, but it's a
waste to throw a shell, especially a live-collected one, away. Just don't
exchange/sell a repaired specimen without telling the recipient beforehand.


Andrew