Flexible collodion for voicing hammers

Horace Greeley hgreeley@leland.Stanford.EDU
Fri Dec 10 11:03 MST 1999


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Bob,

At 12:08 PM 12/10/99 -0500, you wrote:
>Greetings, Horace,

To yourself, as well!

>Three things. First, I assume they used alcohol as a solvent, but did they
>ever also use anything hotter, like acetone, as a diluent?

I do not know that they did or did not.  My experiments with acetone were 
less than successful
in that the solutions became unpredictably "clumpy"; rather like whey with 
really, really
small curds.  I am not sure why that happened, but have simply assumed 
(yes, I know) that
it had to do with some chemical incompatability in what I was using.  Maybe 
one of the
chemists out there can explain what I did wrong.

>Second, I don't see why bleached shellac wouldn't do in this application.

It probably would.  Reality is a matter of perception.  We went through the 
same kind
of political thing between shellac and lacquer as has happened between 
lacquer and
"keytop"  (which, by the way, is not what is used at S&S).  The difference 
is that,
as to shellac and lacquer, the tone produced was (with practice) virtually 
identical.
Most of the acetone/keytop jobs I have followed have been pretty darned 
poor, tonally.

>Third, it seems to me that shellac belongs in the category with some sanding
>sealers and really cheap lacquers in that it has low cohesive strength, and
>is easier to break up when voicing. The "better" lacquers are more toward the
>keytop/acetone end of the very high cohesive strength continuum. I think
>there's a difference in tone, and I suppose one could argue that it comes
>both from the way the two types bind the felt together as well as the way
>they react to needles.

I think that the difference in the media is the difference in their 
designed purpose.
That is, sanding sealer (I do not know about cheap lacquers) fills (sorry) 
a different
purpose than lacquer itself.  While I would agree that the better lacquers have
a higher cohesive strength, they still, to my ear, produce a very different 
sound,
and react very differently over time than does acetone/keytop.

Also, while I tend to agree with your last sentence (certainly as to there 
being
a difference in tone), I am not sure that I do not want to express it somewhat
differently.  Right now, the best I can come up with is that, with lacquer, you
can fairly easily move it around, even after some years have passed.  With 
keytop,
once even the lightest solution is applied and allowed to dry, it takes 
great effort
to make substantive changes.  This has to do with how long it takes to emulsify
the keytop.

I am not sure how much sense this latter makes...sorry.  I'll see if I 
cannot come
up with a better explanation.

Best.

Horace





>Bob Davis

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Horace Greeley,                         email:  hgreeley@stanford.edu
CNA, MCP, RPT
Systems Analyst/Engineer                voice:  650.725.9062
Controller's Office                     fax:    650.725.8014
Stanford University
651 Serra St., RM 100, MC 6215
Stanford, CA 94305-6215

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