Pinblock contamination: myth?

[AlliedPianoCraft]

Greg,

Thanks for saving me the time to write in on this subject. I could not have said it any better.

Al Guecia



From: Greg Graham 
Sent: Tuesday, June 03, 2008 10:38 PM
To: pianotech 
Subject: Pinblock contamination: myth?


The recent thread on how to deal with a few low torque
tuning pins in a new block stirred up the "pinblock
contamination" concern.  

I was talking to another tech who maintains a few (not
one, not two, but several) Steinway D's with loose
pins in the low bass.  Touch the tuning hammer and off
they go type loose.  One or two of the pinblocks are
rebuilds, maybe 10 years old.  I wondered why he
didn't try a light application of CA to solve the
problem.  He said, "I'm waiting for the right time to
use larger pins.  I don't want to contaminate the
blocks."  

How does CA "contaminate" a pin block?  I think of it
as adding some density to the wood.  It is inert.  It
does not attract water and rust pins like the old pin
tighteners did (and still do!).  

It seems like removing a big bass string from a tuning
pin, cranking out the old pin, and pounding in a new
one is much more invasive and risky (to the string),
and certainly more expensive, than just a couple drops
of CA.  You certainly could pound in a larger pin if
the CA didn't work, right?  

Use of larger pins assumes the hole was somehow larger
than it should have been, either because of localized
lower density of the block, or perhaps a hot, dull, or
clogged bit toasted or enlarged the hole.  We assume
the larger pin is a permanent fix, and thus the
"right" repair.  But if the defect is a void or crack,
wouldn't a larger pin make the problem worse where CA
would help fill voids and prevent crack propagation? 
If the problem is low wood density, wouldn't CA
increase the density?

What, exactly, are the risks?  How does CA damage,
contaminate, or in any other way render a pinblock
(new or old) less functional, now or in the future?  

Does it reduce resiliency?  Will the wood not be able
to handle the seasonal movement, causing long term
looseness, even if a larger pin is installed later?  

Are we concerned about jumpy pins?  My experience is
limited, but I have not seen CA cause jumpy pins. 
Have I missed out on the fun?

Does the CA turn the tuning pin into a bumpy reamer
which destroys the hole over time?  (I've heard that
suggested, but never pulled a pin to see for myself. 
I doubt it.)

Are we concerned that there will be visible evidence
of the CA on the plate or bushings that would cause
someone to doubt the quality of the piano, thus
lowering sale price?

I'm not talking about old blocks, and I'm not talking
about heavy amounts of CA.  I'm asking about new
blocks with a few problem pins.  What is the risk of a
light application of CA to the low torque pins?  

And how could this possibly "ruin" a piano?

Greg Graham
Brodheadsville, PA


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