Recrystallizing naphthalene on natural history specimens

Erin Chapman <erchapman75 [at] yahoo__com__au> writes

>My minor thesis topic is the preparation, storage, and care of the
>Queensland Museum's Bat Collection. The bats in the Queensland
>Museum collection were collected to be used for research purposes,
>and as such, are not used for display within the museum. A large
>number of the bats exhibit a white crystalline powder on the outer
>surface of their skin, particularly around the legs and wings. The
>substance does not seem to be deleterious to the specimens.
>Preliminary examination and research into this problem indicates
>that the substance is more likely to be a re-crystallisation of
>naphthalene.

Re-crystallized naphthalene is fairly common on dry biological
specimens in U.S. collections. A simple melting point test can be
helpful in confirming that  the material is naphthalene. It's low
melting point is not shared by most other  pesticides or other
preservatives likely to have been used in the past.

If it is necessary to remove the crystals, either because they
obscure details or because the 'mothball' odor is objectionable,
gentle heat (about 80 deg. F) coupled with good ventilation will
help. If the material is truly  naphthalene, use appropriate health
and safety precautions during the  decontamination process.

Catharine Hawks
Conservator
2419 Barbour Road
Falls Church VA  22043-3026 USA


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                  Conservation DistList Instance 20:33
                Distributed: Tuesday, December 19, 2006
                       Message Id: cdl-20-33-002
                                  ***