Growing Leads

[Elian Degen J.]

Hello List and friends

I used to think in the same way, that it is due to the purity of the lead
used, but I have been observing lately that more and more pianos are
presenting this problem were I live.

Caracas is a tropical place, and here it has been happening from a long
time. We have been seeking a solution to this problem from long ago.

In my experience and other technicians in Venezuela, the only way to "cure"
this problem is changing the leads, we tried everithing, from filing to
cemical treatments, and though you can  slow down the process the end result
is removing and changing.

Last year I had some friends of mine who worked at an investigative lab to
run tests on several leads and the result was as follows.

The basic problem for the lead growth came from the lead reacting with
atmosphere polutants, now a day atmosphere in many cities is becoming acid
due to contamination, that is already known to be causing grat damage to
historical buildings all over the world.

Old pianos took longer, atmosphere was cleaner, but it eventualy happens to
all pianos now, How fast it will be depends on how the lead was handled, If
lead was manufactures in a clean environment wil stay longer, if lead was
made in an already acid environment will start sooner.

If you need more details I can search for the exact report which I do not
know where I filed it, as I can remember it had to do with car and
industrial contamination  and is very much like what you can obsereve in
your car battery when leads react with the battery acid fumes..

Elian Degen


----- Original Message -----
From: "John Delacour" <JD@Pianomaker.co.uk>
To: <pianotech@ptg.org>
Sent: Monday, November 19, 2001 19:50
Subject: Re: Growing Leads


> 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
>
>


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