Silvered brass

I am faced with an art nouveau vase made in brass that has been
silvered. Geometric patterns are enhanced by oxidized zones of the
silvered layer. Conservation is hard as the copper alloy is
oxidizing under the silver layer getting it to blister extensively.

As all decorative patterns are made from the same altered layer, does
someone have a similar experience as to restore the black and white
effect, considering that all surfaces are now oxidized leaving a
pale trace of the complicated pattern. Oxidized zone are getting
clearer and non-treated silvered zones are seriously dull.

We did some tests with potassium cyanide and obtained results but
are aware of the restriction of such a method. Any suggestion will
be greatly appreciated,

David Cottier-Angeli
Metals Conservation and Jeweller


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                  Conservation DistList Instance 16:70
                   Distributed: Monday, May 12, 2003
                       Message Id: cdl-16-70-014
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