Water on hammers

[Bill Ballard]

I knew that at some point there would be a thread which would yank me back
to the table.

A couple of points:

It should be clear after the first two days of posts that whatever part the
alcohol may actually play in the process, softening the lacquer is not
included. Del reminds us all that none of the resins now used for hammer
stiffening (nitro lacquer or keytop) are at all alcohol soluble. Years ago,
hammer stiffening was done with shellac, but that was years ago. In fact,
as it was stated into the earlier mentioned PTJ article ("Alternative
Voicing Methods" or was it "Voicing Methods Which Work"), alcohol breaks
the surface tension of the water so that the water can be absorbed by the
felt matte. Once absorbed the water can exert its power on the matte,
causing it to open up. What we are talking about is increasingly the air
space between the felt fibers in the matte. If there is no air space then
the matte has no way of compressing under the impact with the string and
rebounding. Does this sound like a hammer with no resilience. Y'bet!@#@!

The means by which these resins stiffen up the hammer are threefold. First,
the resin coats the fiber itself, making it stiffer and "slower to move".
Second it can glue neighboring fibers together. Finally, in extreme doses
(are rather "douses") it can literally fill up the air spaces between
fibers. In any case, the ability of the fibers to bend is restricted. Thus
prevented from bending under the felt's impact with the string, the natural
springiness of the felt is not employed as a mechanism to provide a prompt
rebound from the string. Water, not alcohol is what undoes the rigidifying
of the felt mass, simply by forcing the mass to expand. Surprised that
water could overcome these hardened resins. Why not? Freeze water and it'll
split granite for you.

Posts in this thread have mentioned that one or another method of voicing
is hard to control. Some say that about water/alc, others about steam. We
all learned our first lesson about the difficulty of controlling a method
of altering hammer felt flexibility with nitro lacquer (or if you're that
new, ground keytop). What I learned from that lesson is not to expect my
experience to tell me how any given set of hammers is going to react to a
procedure (ie, over or undershoot), but that I should apply a measured
amount of the procedure to a set of samples to find out how 4 out of 88
hammers are going to respond rather than 40 out of 88. I look for groups of
thee notes, side by side, with identical tone. Hopefully I can get four or
five groups across the entire scale. I then do the application on the
center of these trios, and following the required time, check for the
results. I like to undershoot rather than over, except that with hardeners
you really need to hit it the first time. (Subsequent doses will not soak
in nearly as evenly because the absorptive ability of the felt mass has be
greatly reduced by the first dose.)

The results on these test (or more likely, "guide") hammers as compared
with their previously identical neighbors, tells me how to proceed with the
application in that region. In the case where I have significanlty
undershot on the guides, these guides may get the same measure of the
application as the others in that region, so that once again, the guides
serve as "point men", advance notice of where the procedure will take the
hammers.

I've done it thus hardening with nitro lacquer or ground keytop, and
softening with water/alc and steam. Hard to control? Not if you know in
advance where the application will take you.

Incidentally, Del talks about wanting to flush the resins out. There is a
Boston area technician who achieves beautiful results by making sure that
however much the rest of the hammer gets stiffened, there is absolutely no
resin right at the strike point itself (where fiber meets string, or road
meet rubber). He should do the honors of detailing this technique for the
much larger audience than the one-on-one in which he related it to me. (He
should also be on this list.) I have dreamt of exploring this technique,
but it would involve doping the hammer with a colored plastic and one whose
dye would no more soluble by acetone than the plastic resins. (If they
were, then the dyes would migrate faster than the resins, under a
high-pressure application of acetone. I want to witness the flushing of
resin, not dye, thank you.) Maybe in the interst of science, Bob Marinelli
could be prevailed upon to come up with just such a material.

Dell writes, 11/26
>So, forget about the lead; let the battle cry be, "Get the lacquer out!"

Sorry, Del (although respectfully so). While lead may spoil feel as lacquer
does sound, and while pianists can rarely separate sound from feel, we
technicians know that there is plenty of work to be done in both areas of
the piano.

Bill Ballard, RPT
New Hampshire Chapter, PTG

"You'll make more money selling my advice than following it" Steve Forbes,
quoting his father, Malcome.