Copper beads

Carrie Duran <carried [at] cityofgastonia__com> writes

>We have some copper beads from an archaeological site in Gaston
>County, NC.  We would like to do some specialized analysis on them,
>but they are too oxidized to get accurate readings.  They appear to
>be almost pure copper because there are no alloys to suggest
>European copper. ...

Rather than enumerate actual conservation treatments for
archaeological copper here, I would suggest that you contact an
archaeological conservator either in your state or in South
Carolina.  There are safe methods to clean copper, but it's
difficult to know what the matrix consists of and the condition of
the objects from the written description above.  Treatment could
lead to damage or loss of the objects.  The objects might require
consolidation first in order to safely clean them.  You are correct
not to use an abrasive method.  Depending on your method of
analysis, you might be able to clean a small area on a bead, rather
than the entire object.  This might seem to be an obstructionist
response, but being familiar with the fragility of native copper
objects both in collections and in the field, I'd rather stick to
the side of caution.

The unidentified piece shouldn't be immersed in water in case that
it is a composite object.  I've come across copper objects in the
field that were actually thin sheets of the metal over bone, as in
the case of a pair of copper ear spools that I excavated.  Immersion
would have caused those objects to break up.  Careful mechanical
cleaning along with softening the soil matrix with dampened cotton
swabs might work.

The AIC Code of Ethics and Guidelines for Practice, Commentaries for
Examination and Scientific Investigation, Guidelines 16-18 will give
you information on how conservators approach this type of problem,
including guidelines for preparation treatment, sampling, and proper
documentation.

Paul S. Storch
Senior Objects Conservator
Daniels Objects Conservation Laboratory (DOCL)
B-109.1, Minnesota History Center
345 Kellogg Blvd. West
St. Paul, MN  55102-1906
651-297-5774
Fax: 651-297-2967


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                  Conservation DistList Instance 19:3
                  Distributed: Thursday, June 23, 2005
                        Message Id: cdl-19-3-010
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