[pianotech] acetone for hammer hardening

[Ed Foote]

Greetings, 
     I just returned from my distant work, and I used acetone/lacquer for the hammer juice.  These were S&S hammers I installed in 2003.  I had done a medium/ light soak of the shoulders with a 5/1 ratio at the time.  It wasn't enough , and they never developed that round, punchy, sound with a slight shimmer around the edges for definition that would gradually turn to steely edge when FF was reached.  
      So, I rehardened them.  I used 5/1 acetone/lacquer.  The top octave or so got a full eyedropper, right over the crown, soaking the entire felt. As I moved farther down the scale, I began soaking into the shoulders again, letting the wet spot from both sides meet in the middle at the tip of the core.  By the middle of the piano, I also began adding  the hardener to the sides of the hammer, with the tip of the eyedropper directly over the tip of the core.  I made a wet spot about 70% the size of the hammer,and I did it just from the treble side, figuring,what the hell, this might make the una corda really special.  
 
    I did this with a preplanned return trip in two weeks, (after getting married on the 22nd), to prep it for a concerto.  I was told to favor excessive brilliance that could be brought down at that time, rather than risk needing another juicing the day before the performance, since I would not be there to follow up, and am loathe to blindly throw a lacquering job into a concert setting.  
       It worked.  By the end of the day, 8 hours had passed with a fan blowing on the hammer line anytime I had it out.  There was a definite crispness to the whole piano, and those notes that heretofore had refused to yelp when  really  pounded upon, are now willing and eager speak their mind.  That was in one day.  I managed a quick look at the piano the following morning, and it was slightly brighter than the previous evening.  Nothing was totally pinging, but there was a slight aroma of acetone in the a.m. so I suspect more effect will be forthcoming as the lacquer, wilted by a tide of solvent flooding in, slowly settles back into its stiffer state. 


Ed Foote RPT
http://www.piano-tuners.org/edfoote/index.html

 
>>I use keytops in acetone all the time. You can speed it up with a hair
dryer and get pretty predictable results in 2 hours.

Doug Gregg 

 
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