Paul Monfils and Peter Froehlich have spoken out very well, giving 98
cents' worth of the advice on this subject. They left only 2 cents' worth
to be said.
 
Some solvents will slowly evaporate from closed containers once the seal is
broken. They should definitely be stored in a locked area that does not
share ventilated air with your living area, or your pets' living area. An
outdoor storage shed, perhaps, if its climatic conditions are proper. Some
solvents are so volatile and dangerous that they should be stored in an
operating fume hood; obviously, it's best to plan for using these chemicals
up in a short period of time rather than storing them indefinitely. These
considerations are especially important in centrally air-conditioned and
heated homes with sealed windows and recirculated air in which the gaseous
solvent can be concentrated. Some are potent carcinogens (e.g., benzene and
similar compounds); others can cause serious, irreversible liver or kidney
damage. Don't be afraid of your chemicals, but do treat them with respect,
and learn how to handle them before you buy and use them.
 
And please make sure that they are properly labeled; don't ever store a
chemical in an unmarked jar, not even distilled water, not even overnight.
If something ever happened to you, your friends or relatives would have a
dangerous (and possibly expensive) task to perform in identifying and
properly disposing of chemicals. An unmarked jar of distilled water would
have to be treated as dangerous until proven otherwise. And what if you
reached for an unmarked squeeze bottle of water and found, too late, that
it was hydrochloric acid? Goodbye, shell!
 
As to identifying ancient shellac and other preservatives in old
collections, consult "Fossil Animal Remains" (or "Preserving Fossil Animal
Remains"?--sorry, I don't have the exact reference; that was another
university library and another job!). This book is the best I've seen for
identification and removal of old preservatives, recipes for new ones, and
general advice. It was intended largely for treatment of fossil bones, but
the chemicals are the same as those used for fossil and modern shells. It's
probably out of print by now, but it should be obtainable by Interlibrary
Loan. I don't remember enough from the book to be able to give much advice
on the subject, except that beeswax is extremely difficult to remove, and
that shellac will eventually peel and destroy the specimen it is intended
to preserve. Elmer's glue (or white glue) was formerly made of colloidal
bone material, and one version still is, but most white glue is now made of
polyvinyl acetate. They are normally thinned with water, about half and
half. Both are safe enough to be handled by children, and both can be
removed fairly easily, although less so as time goes on. Since the Survey
collection has no running water, let alone a fume hood, that's what I
mostly use, but I'm behind the times. Most museums are using Butvar these
days to repair and stabilize bones and shells.
 
Best of all is to use NOTHING, if your specimens can last without
treatment. If it ain't broke, don't pour fixative on it!
 
Have fun and work safely,
 
Andrew K. Rindsberg
Geological Survey of Alabama