Removing nickel plating from silver plated brass

I have been asked to work on a couple of tall (1.2 meter) Russian
mid 19th century candle sticks made of brass (1mm) which were silver
plated originally. For unknown reasons (because the silverplate was
worn I guess) the candle sticks are plated with a thick nickel layer
in the past (there is no silver layer on top of the nickel present).
The nickel layer is showing blisters. Next to that a lot of
alterations are made and repairs with tin/lead solder have been
carried out.

The Russian Orthodox Church as user of the candle sticks would like
to have the candle sticks restored to their original  beauty. The
candle stick are part of a large ensemble of silver, gilded silver
and gold objects. The ensemble is on the exclusive list of "Dutch
protected collections" and these object are of highly cultural value.

With hesitation, I do understand the need for the removal of the
nickel (it would stand out too much from the rest of the ensemble,
and will be taken care of much better when they are in a better
state). After removal of the nickel the candle stick will probably
be plated with silver again. The use of a protective coating is
still being discussed.

I would like advice on how to remove the nickel without attacking
the brass underneath. Information on methods that do not work or
that will harm the brass are very welcome also. I'm especially
interested in comments on the use of a commercial product for
removal of nickel known as B-929 from Metlalx and the use of a 60/40
sulfuric acid/H20 galvanic bath.

Michiel Langeveld
M Langeveld MetaalRestauratie
Michiel Langeveld
Zamenhofstraat 150
Unit 238
1022 AG Amsterdam


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                  Conservation DistList Instance 24:23
                 Distributed: Friday, October 29, 2010
                       Message Id: cdl-24-23-012
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