Shellac vs. lacquer

[David Love]

This is all assuming that the contribution of "hammer hardeners" is to
increase stiffness of the individual fibers rather than overall density of
the hammer.  I'm inclined to believe that it's the overall density that
increases and the flexibility or compressibility decreases as a function of
that.

David Love


----- Original Message -----
From: "Bill Ballard" <yardbird@pop.vermontel.net>
To: <pianotech@ptg.org>
Sent: July 16, 2002 4:36 AM
Subject: Re: Shellac vs. lacquer


At 2:37 PM +0200 7/15/02, Richard Brekne wrote:
>Holy Christmas Bill... you used at least eight 67 cent words
>there... :) gets complicated for this Norwegianized mind of
>mine.

They cost me at least $4.95 apiece. You'll see a noticeable mark-up
in the invoices I'm sending out. The big challenge to the internet
economy is creating revenue streams out of all this digital traffic.

>If you want an idea of how Shellack is going to behave over
>time inside the hammer take a thick dense strip of felt (for
>example damper lift felt for the back end of grand keys) and
>soak a short strip of it in Shellack and let dry. The have
>fun playing around with it in as many creative ways as you
>can think of and check out how it reacts.

At 10:45 AM -0700 7/15/02, Susan Kline wrote:
>Now if you want the real gritty about what the stuff does to felt
>fibers, why don't you take a scrap hammer, soak it well in shellac,
>dry it out, vise it to something sturdy with the felt aiming
>upwards, and whack it with a mallet a bunch of times? Then take your
>knife, cut it open, and put thin slices on a microscope slide?

Sounds like the test for ductility of music wire. I was contemplating
something on the single fiber scale, and which would compare resins.

>As for whether this whole process leaves the elasticity
>decimated or not I dont know.... try stretching the strip
>above and see how snappy it is ! Tho I have to wonder if
>your segmentation would like reaaaly be synomonous with
>chopping the felt fibers into a million short peices with
>one of those Japanese knife thingys. :)

I should clarify. The elasticity I'd like to witness is that of the
resin by itself. Heck you could make a reinforcer out of watered-down
TiteBond. Its elasticity would be greater than keytop plastic. For me
what distinguishes these resins (lac bug stools, nitro lacquer,
shellac and keytop plastic) in their results is their springiness.
(Oh, cure time is also a major consideration, but in the scheduling
of the work, not necessarily in tone quality.)

I seriously doubt there is any chemical reaction between the felt
fiber and and the resins which would degrade the fiber (and
specifically, its elasticity). The behavior of the combination i
would bet is entirely a mechanical matter.

Under a powerful microscope, coat a single fiber. The fiber's
springiness is a known factor. The resin coating stiffens the fiber,
making it slower to bend under a deforming force (ie. collision with
taut music wire). But there's a big difference in how that fiber will
return from the deformation, based on the elasticity of the resin.
I'd like the resin with the greatest elasticity. Any coating can
stiffen the fiber, I'm looking for one which will contribute some of
its own elasticity to the fiber, after reducing the fiber's
elasticity.

Yes the breakdown is a significant determinant in the long-term
prospects for sound. Thanks to Richard for bringing this up. Imagine
the resin coating as a sheath. Its brittleness/elasticity will
determine how its will survive the flexing which occurs with each
hammer strike. (Certainly that flexing is likely to exceed the
elastic limits of the resin mainly at the strike point.) The
segmentation I was exploring happens when the flexing overcomes the
resin's limits. At that point, wouldn't the coating have fractured
into segments. And now, coating the fiber not as a single sheath but
in many short segments, wouldn't it it have lost the original
stiffness it had as an integral whole sheath? Would its effect on the
fiber now mainly be limited to its mass, now clinging on to the fiber
i separate chunks?

This is what pricked up my ears when Richard talked about the warming
of the sound as resin breaks down. I'm actually looking forward to
this process with shellac, because I haven't noticed it with keytop
plastic.

At 10:45 AM -0700 7/15/02, Susan Kline wrote:
>P.S. A blow-by-blow of your return visit to voice that set of
>hammers would be very welcome! I've used shellac for voicing, but
>never for building up a new set of hammers from scratch before.

I will probably do the report tomorrow night. Tuesday is one of three
nights per week during the summer when I have two concert running, 45
minutes drive apart.

Briefly, this is a D with the whole nine yards done last year (I did
a new action with complete Stanwood), sitting in a concert shed
(http://www.svac.org/2002_final/wed.html), with a theater stage and
proscenium. I didn't push the reinforcing too hard last season, as
I'm a firm believer in the "work-hardening" of the strike point. But
the time hard come to make the piano project. So from that
standpoint, the shellacing is part of the initial set-up. I got over
there yesterday and found the piano much as I remembered it from the
week before (and anticipated finding it). So 1.5 hours of loud
voicing (with Zen Reinhardt's "racket-ball"), mezzo, then U.C., and
finally quiet voicing. The piano is no ready for the opinions of
others.

Bill Ballard RPT
NH Chapter, P.T.G.

"I gotta go ta woik...."
     ...........Ian Shoales, Duck's Breath Mystery Theater
+++++++++++++++++++++