Non-destructive testing of bronze sculptures

I am organising the assessment of some cracks in large bronze
sculptures to determine whether they pose a structural problem.  I
have had two quotations so far--one for digital radiography and the
other for dye penetrant analysis using a fluorescent dye.  Both
methods seem to have some drawbacks.

The x-rays would have to be taken from the correct angle to spot the
cracks.  I am concerned that the dye penetrant analysis may not work
on a waxed surface and could lead to changes in the patina.  I am
also not sure of the long term effects of the dye residues.  I have
seen some references in the literature to eddy current and
ultrasonic testing which may be better options, but there doesn't
seem to be much information available in English.

Can anyone comment on the efficacy of non-destructive testing
methods for assessing cracks in bronzes?

Vanessa Roth
Objects Conservator
Art Gallery of Western Australia


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                  Conservation DistList Instance 18:54
                   Distributed: Friday, May 20, 2005
                       Message Id: cdl-18-54-024
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