Mold on bone

Barbara Appelbaum <aandh<-a t->idt< . >net> writes

>Re: Gina Overshiner's moldy bones, don't use anything that is not
>completely volatile. Use straight ethanol as long as it won't
>dissolve any consolidants. I wouldn't suggest dry silica gel
>because it will dry too much. Mold shouldn't be starting to grow at
>52%: did some moisture get into the containers?

First be sure what you have *before* you use ethanol or any other
solvent on the bone problem. There are several possibilities here,
including efflorescence of salts from the original environment,
trace pesticides and fumigants, misbehaving old
adhesives/consolidants, etc.

I agree that 52% RH argues against vigorous mold growth. Lots of
people have spent lots of money on "mold" treatments only to find
out that the problem is not and never was mold. Complex salt
efflorescences such as Byne's "disease" in calcium carbonate
structures can really fool you if you don't look closely. Bone is
not calcium carbonate, but is just as susceptible to picking up
salts in solution from burial environments, old preparation methods,
odd storage environments, etc. Old treatments, including arsenic and
other pesticides, can redeposit on the surface over time. Don't
guess and don't go by surface appearance, and definitely steer clear
of solvents until you know what's going on.

Mold and other biological growths separate themselves nicely from
mineral efflorescences under normal microscopy. Dealing with molds
is, sadly, much easier than identifying and dealing with
non-biological efflorescences, but that does not mean that you
should treat unknown outgrowths as if they were all alive. Don't
clean the bone surface with ethanol as a default measure--this isn't
medical science. One: it won't do any good if the problem is an
efflorescence. Two: it can liberate noxious substances and make it
easier for you to be exposed to them. Three: it will destroy any
important trace evidence (such as soil, pollen, blood, etc.) at the
surface and may provide some unwelcome dissolution of compounds in
the bone itself. Cleaning is an interventive treatment and can do
more harm than good in such cases.

Both molds and mineral efflorescences can be very dangerous to human
health. Be sure that you are protecting yourself from contacting or
breathing any unknown substance. If the culprit is clearly not
biological, get a chemist or geologist in on the act and get the
substance identified. Then you'll know better how to proceed.

And do beware of over-drying bone: as has already been pointed out,
this is very detrimental to its structural integrity. At 52% RH,
assuming that's accurate, you shouldn't need an aggressive drying
regime. Hold off on the desiccants until you know what you have. Cheers,

Sally Shelton
Director, Collections Care and Conservation
President-Elect, Society for the Preservation of Natural History
    Collections
San Diego Natural History Museum
P.O. Box 1390
San Diego, California  92112
619-232-3821
Fax: 619-232-0248

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                  Conservation DistList Instance 10:90
                  Distributed: Tuesday, April 22, 1997
                       Message Id: cdl-10-90-002
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