German silver parallel rule

I am about to conserve a parallel rule, a surveying instrument made
in the UK towards the end of the 19th century and sold in Australia
where it now is. There appear to be some copper coloured "corrosion
products" on it at intervals but otherwise the rule is merely dull.
The curator would like the finished effect to be corrosion free
though not very shiny and to be lacquered to prevent further
deterioration. Has anyone any experience in dealing with German
silver (nickel silver)? Is the copper colour indeed copper due to
loss of nickel? What does anyone advise on cleaning and protective
coating?


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                  Conservation DistList Instance 14:2
                  Distributed: Thursday, June 29, 2000
                        Message Id: cdl-14-2-026
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