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Subject: Polyurethane and modern human bones

Polyurethane and modern human bones

From: Niccolo Caldararo <caldararo>
Date: Tuesday, December 1, 1998
This is a response to Sally Shelton and Greg Hodgins' comments to
Tom Bodkin's post on his treatment of bone with polyurethane.  While
Sally's advice is prudent to determine what material may be of value
for DNA and other sampling in the future, this is impossible to
address in a practical sense.  I debated this with Gary Thomson at
an IIC meeting in 1982.  Gary argued that sampling could provide us
with sufficient materials for future analysis.  The problem here is
that the demands for samples have changed over time and the location
of samples varies for the specific requirements of different
analytical inquiries, for example those of dietary importance
regarding trace elements vs ancient DNA which may survive better due
to the structure of the enamel.

Sometimes D/L ratios will vary over a skeleton indicating different
rates of degradation due to microenvironments in the soil.  I have
written on many of the issues involved and published a summary of
methods in the Journal of the American Institute for Conservation in
1987, and particular problems for archaeological conservators in
North American Archaeologist (1993).  The best solution in my mind
is to do as little consolidation as possible, especially in the
field and invest in better storage conditions recording keeping.

Greg is correct with reference to Carbon 14 and other dating methods
and conservation treatments, I published a review on this in
Radiocarbon in 1994. Greg's proposal on full reports on treatments
as well as an effort to collect data on earlier treatments would be
most valuable.

Niccolo Caldararo
Director and Chief Conservator
Conservation Art Service

                  Conservation DistList Instance 12:49
                Distributed: Wednesday, December 2, 1998
                       Message Id: cdl-12-49-001
Received on Tuesday, 1 December, 1998

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