[pianotech] Are Pressure Ridges and Cracks Acceptable on a Piano 4 Years Old

[David Love]

Compression crowning tends to form compression ridges.  Sometimes  those
pressure ridges will be there before the piano leaves the factory.
Manufacturers will not warrantee against pressure ridges in fact Steinway
claims that it is a sign of "good" compression in the panel.  The archives
are replete with discussions and arguments back the short and long term
implications of pressure ridges and a search over the past couple of years
will bear much fruit.   Personally, I do not like to see pressure ridges as
it indicates damage to the wood cells along that particular grain line.
Over time it's there that cracks tend to form.  While the crack itself does
not compromise tone, that the crack or pressure ridge has formed indicates
damage and a structural weakening of the panel, i.e. a loss of stiffness.
Since tonal degradation in soundboard panels is often related to loss of
stiffness it is not a good sign.  To guard against over compressing the
panel it would have to be ribbed at a lower EMC such that the requisite
stiffness might not be created in the first place.  While that might prevent
the formation of pressure ridges or panel damage, the lack of stiffness
might compromise the tonal response-especially during periods of low
humidity.  That is largely the basis for the ongoing debate about pure rib
crowned boards where the crown is formed by shaping the ribs to the desired
radius or hybrid designs that use rib crowing plus some more modest
compression crowning to try and avoid compression damage.    

 

What I think in your case is that it should be brought to the attention of
the manufacturer and see what they say.  I wouldn't hold out hope that they
will offer a remedy.  

 

David Love

www.davidlovepianos.com

 

From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf
Of Lynn Hall
Sent: Monday, December 29, 2008 3:06 PM
To: pianotech at ptg.org
Subject: [pianotech] Are Pressure Ridges and Cracks Acceptable on a Piano 4
Years Old

 


Since I am not a Technician,

 

Are Pressure Ridges and Cracks acceptable on a high end piano less than 4
years old, that has a damp chaser and also the environment is meticulously
regulated and maintained within guidelines established by the industry? 

 

What do a majority of technicians think about this?

 

 

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