Growing Leads

[John Delacour]

At 3:54 PM +0930 11/19/01, Tony Caught wrote:

>Got a problem with growing leads in the keys of a Herburger keyboard 
>fitted to a Schimmel grand piano.

Must be an old one.

>Does anyone know how to arrest the growth problem ? Can drilling a 
>small hole in the middle of the lead help ? What is the major cause 
>of this oxidisation ?

The cause is impure lead.  It only happens with certain makers at 
certain times.  Good quality refined lead will not oxidize but 
weights made from lead recycled by the night raiders, the plumbers 
etc. contains porous impurities and acidic stuff that help any 
moisture about to pulverize the lead.

If it's not gone too far and split the keys, remove the swellings 
with a sharp chisel (files and abrasives just make a dreadful mess) 
and paint the sides with shellac.

If it has, replace the lead with new from a source that can guarantee 
its purity (and that might not be easy).  I recently had some leads 
from Renner in Stuttgart that were of two completely different 
qualities.  I sometimes think it'd be best to make my own.  Lead can 
be purified on the kitchen stove, as I learned from long experience 
as a child.

JD