A First Tuning (and tuning / moisture content stability question)

[piannaman at aol.com]

 ----Original Message-----
From: Ron Nossaman <rnossaman at cox.net>
To: Pianotech List <pianotech at ptg.org>
Sent: Sat, 3 Jun 2006 09:58:08 -0500
Subject: Re: A First Tuning (and tuning / moisture content stability question)


 
> I've seen quite a few pianos that live in abysmal conditions that seem > quite stable. Maybe some of the soundboard specialists out there could > enlighten us: do older spruce panels maintain a more stable moisture > content than newer ones? This question is not intended to ask whether > older wood is of better quality than the newer spruce(we all know that > everything from the old days is better than anything new.....:-{> ) I'm > just wondering about the effects of aging on spruce. Less flex, but > more stability perhaps? 
> > Dale, Ron O., Ron N.??? 
> > Dave Stahl 
 
>I doubt that old wood's ability to absorb and desorb moisture is much different than that of new wood. The fact that compression crowned boards lose crown and develop cracks would seem to indicate that compression damage has some affect on the wood's dimensional reaction to moisture changes. For what it's worth, doing the math indicates to me that soundboard rise and fall is only a minor player in tuning changes with humidity swings. The bridge cap moving the strings up and down the staggered and slanted bridge pins accounts for a greater string path length difference. The bridge cap is subject to the same sort of compression damage as the soundboard panel, and should also become less reactive to humidity swings as a result. 
Ron N >
 
Makes sense.  So when you get an old piano that has bridge cap AND soundboard compression damage, you get a piano that is stable tuning-wise, but is unlikely to sound particularly good.
 
Thanks,
 
Dave
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