VERDIGRIS IS COPPER CORROSION

[Piano Forte Supply]

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There are two types of center pins used today that I am aware of: nickel 
plated brass and German silver.
Brass is composed of copper (56 - 67%) and zinc.  German silver is 
composed of copper (46 - 66%), zinc (9 - 42%) and nickel (8 - 36%).  As 
I see it, there is no getting past copper as a component in center pins.

On many old pianos the verdigris is probably due to lubricants and 
enviromental factors over the centuries.  As well, the thin plating may 
have worn, leading to exposure of pure brass to the bushing.  I am 
talking about flanges that weren't dipped in a "preservative" like so 
many of the old Steinways.  I believe on these actions, one can get very 
good results by rebushing the flanges.  A lot of work, no doubt, but the 
only way to go if parts can't be had.

A great help in rebushing whole rails is the use of the European style 2 
foot long center pin wires.  Rebushed flanges can be strung up on these 
for the glue drying/bushing shrinking/sizing steps.

Jurgen Goering
Piano Forte Supply

>
>VERDIGRIS is an oxidation of COPPER without COPPER it
>CAN NOT EXIST!!!!! In the felt, or the pin. Probably
>the pin. So what is the composition of pins today, so
>that it can't arise. SIMPLE QUESTION!
>     Thump 
>
>  
>

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