[pianotech] piano behavior - shrinking with H20 & alcohol

[Tom Driscoll]

David,
 Comments interspersed below
  ----- Original Message ----- 
  From: David Skolnik 
  To: pianotech at ptg.org 
  Sent: Monday, November 21, 2011 10:30 AM
  Subject: Re: [pianotech] piano behavior - shrinking with H20 & alcohol


  Tom -
  Just curious.  How do you know it's a case for shrinking? 

  Many acrosonic actions from the 50's-60's have sluggush centers. My first test is to depress the left pedal and release quickly. If the hammers don't follow the returning rail the action has " Baldwin disease ". Lubes will help but based on experience not very well and /or not for long. 
  No matter what the action if a center frees up completely and immediately with protek then shrinking is less likely to be needed

   Have you tried naptha and exercising the part (taken off the rail)? 

  Naptha will clean out gunk (not vertigris) but in my experience is not very helpful.
  Taking the parts off the rail ? Way too much time when you can excercise the centers in place

   I know there's the issue of retaining proper alignment,
    
  Alignment stinks on most Baldwin verticals anyway --especially hammer spacing-traveling 
   
  but I wonder what your experience has been in controlling the amount of shrinkage.  Do you use a pharmaceutical grade alcohol with a controlled water content?  I ask because I have not had many occasions to employ the method, and not glowing success when I have.  I'm sure it's me.

  Back in the 70's I was instructed to use methanol from the drug store mixed 50-50 with water but
  it's not available in small quantities anymore (to my knowledge) . I was using cheap vodka from the NH state liquor store which was cheaper than buying the methanol, but since have been advised by my list brethren that denatured alc solvent mixed 50% with water works as well. I don't think there is any magic formula here. The alc. cuts through the lanolin in the wool and introduces the water into the wool fibers . I've heard a few theories as to what happens to the  center. The fibers shrink as a wool sweater shrinks when washed. The fibers are trapped between the wood of the flange and the center pin and compress as they swell and when dry free up the center. Pick the theory that suits you but in any case this is a method that has been used for ever  . 
      I juiced up all the centers  this morning . 12 hours later with only air drying (42% RH in the shop today) and the worst hammer -butt assembly sample now has 8 swings from 2 swings before the treatment .
  Most recently I've sized several over tight damper guide rail bushings on new Chinese pianos 

  Tom D.

  P.S. The best reason for ditching the vodka concoction is it gives the wrong impression to the client when they see the bottle on the work bench

  David Skolnik
  Hastings on Hudson, NY 



  At 09:40 AM 11/21/2011, you wrote:



         Others such as the Baldwin action on my bench now will need shrinking.



        Tom Driscoll 

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