[pianotech] Expanding Leads

[tnrwim at aol.com]

So, there has to be
something in certain types of lead that promote the expanding thing. Seems
we need someone with a whole lot more chemistry knowledge than me. Greg?
Any thoughts?
Best,
Joe





Joe

This is where the mystery lies. As I stated, on the same piano, some leads will be corroded, and some not. Very mysterious. 

I do agree that the salt air probably contributes to the problem, and while we have a lot of salt air near the ocean, we live 10 miles inland, and it's not evident in our house. Yet, I've seen pianos in my neighborhood with this problem. (But then they might have been brought here from a house close to the beach). 

Yes, we need someone with a lot more knowledge on this subject to chime in.

Wim

 



-----Original Message-----
From: Joseph Garrett <joegarrett at earthlink.net>
To: pianotech <pianotech at ptg.org>
Sent: Tue, Mar 12, 2013 1:02 pm
Subject: Re: [pianotech] Expanding Leads


David said: 
"Yes, there does seem to be a humidity factor and I was wondering about how
that might trigger a bad batch of lead. At least the ones I've encountered
did have exposure to high humidity, this one included. My concern with just
trimming them is that others that I've seen have expanded such that the keys
were splitting. If that happens on this piano with ivory on it , or in the
underlevers then the cost of repair could skyrocket. We will opt to replace
everything and reweigh the keyset at the same go. Of course, the value of
the piano, in this case, does warrant it."

David,
It's been my experience that it is more than just humidity. I believe the
entire environment has something to do with it as well.In Wim's case, there
is the issue of high salt content in the atmosphere in Hawaii.<G> In the
case of the English Overdamper pianos, (which is the most of this problem,
I've encountered), there was not only humidity, but coal dust and fumes,
i.e. sulfer and co 2. Plus poor ventilation such as cooking vapors, such as
Pickling...vinegar etc. Lead reacts to all of these things. It can be made
to stop that process IF one can seal it from further air-borne problems.
That is the real problem. I have found that spraying, (after trimming),
with either lacquer or varathane will pretty much stop it in it's tracks.
however, the whole key stick needs to be sealed not just the immediate area
around the lead slug. Most new lead, that we get from our suppliers is not
pure, but has a certain amount of tin in it. The Tin is what keeps our
wheel balancing leads from going into major corrosion mode. Pure lead, on
the other hand seems to be impervious to corrosion too. So, there has to be
something in certain types of lead that promote the expanding thing. Seems
we need someone with a whole lot more chemistry knowledge than me. Greg?
Any thoughts?
Best,
Joe


Joe Garrett, R.P.T.
Captain of the Tool Police
Squares R I
http://gpianoworks.com/


 
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