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Subject: Cleaning metal

Cleaning metal

From: Jack Ogden <jack>
Date: Wednesday, March 31, 2004
Melissa Marsh Heaver <mmheaver [at] aol__com> writes

>In my spare time, I am on the Vestry of my local church. We have a
>nickel and silver alloy cross, c. 1957, that hangs from the ceiling.
> ...
>It has been taken down for Lent, and stored. We hope to have it
>cleaned and probably relacquered, as it hasn't been down in at least
>15 years. The local person the church wants to do the job is
>suggesting that it be cleaned via "sand-blasting", but with glass
>beads. Is this a wise idea, or will we be removing metal? If this
>method isn't a good idea, is there anything else we can use to clean
>it and get the grunge off?

Are you sure this is a nickel silver alloy rather than 'nickel
silver' another common term for a cupro nickel alloy that is usually
electroplated with silver (In the UK such stuff is often stamped
'EPNS' = 'electroplated nickel silver'

If the cross does have a thin electrodeposited layer of silver, any
type of abrasive cleaning could remove all or part of this.

These types of objects were commonly lacquered at the time of
manufacture and as the lacquer layer become patchy with age (and
cleaning) the tarnishing of the object can become irregular and
pretty awful.

If you took this to a normal silver repair workshop they would
typically strip off the remaining lacquer (using chemical solvents
if possible), clean and examine the silver plated layer and either
repolish this with mild silver polishes or, if the plated layer was
too thin and worn, strip this off and re-plate.

Obviously if it were a 1557 cross, such a drastic approach would be
unwise, but it is 1957 ...

Of course that opens the whole debate about conservation ethics when
religious objects are involved. Some cathedrals still prefer to turn
to a goldsmith with a hammer and a soldering iron to repair their
Medieval treasures, because the object and its use is sacred, they
need it on Sunday and besides you can't honour God with a dented
chalice. Tricky one,

Jack Ogden
Osmiridium Consultancy

                  Conservation DistList Instance 17:64
                  Distributed: Thursday, April 1, 2004
                       Message Id: cdl-17-64-001
Received on Wednesday, 31 March, 2004

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