Shellac vs. lacquer

[Kdivad@AOL.COM]

In a message dated Wed, 17 Jul 2002 5:40:01 PM Eastern Standard Time, davidlovepianos@earthlink.net writes:

> 
> 
> Bill:
> 
> I am still inclined to opt for the higher density explanation.  When you
> compare a NY Steinway hammer to a Renner or Abel hammer, it seems unlikely
> that you would find a different in the stiffness of the individual fibers
> accounting for their tonal difference.  When inserting a single needle into
> each hammer it seems that the difference in felt density is evident.  Abel
> and Renner achieve that difference through the use of higher density felt to
> begin with, perhaps, plus the application of heat during the manufacturing
> process which shrinks the felt down to a denser mass.  You can see this when
> you needle the hammers and the hammer expands.  You can also achieve a
> louder or brighter tone on one of these hammers by soaking the hammer with
> acetone.  Presumably this doesn't stiffen the fibers, but causes some kind
> of shrinkage which, again, makes the hammer more dense.  Moreover, you can
> brighten the tone in a NY Steinway hammer by ironing the felt.  It is hard
> to imagine how this would stiffen the individual fibers.  It seems more
> likely that it compacts the felt at the crown: more density equals brighter
> sound.

David, I agree with you on the density theory, in my experience it feels right, though there is apt to be some measurable difference in fiber stiffness due to manufacturing processes.  This stiffness seems to me to break down somewhat rapidly with the immediate impact flexing of a fresh hammer striking the string, but density is another story.    
> 
> The fact that certain hardeners "break down" seems more a function of how
> deeply the hardener penetrates.  If it lies on the surface or crown of the
> hammer, then as the surface wears away with playing so does the hardened
> felt.  This process is complicated by the fact that the same playing that
> wears away the densified felt also packs the felt down underneath.  So
> sometimes a little bit of hardening of the crown is a nice temporary measure
> until the hardener is worn through and the natural compacting of the felt
> takes over.

Straight forward and makes good sense, that is why I prefer to voice down a "dense" hammer in general rether than voice up.

> 
> It seems that what many of us are looking for is a hammer which is somewhat
> more dense than a NY Steinway hammer and somewhat less dense than a Renner
> or Abel hammer.  One interesting experiment might be to take a NY Steinway
> hammer, infuse it with an alcohol and water solution and throw it into the
> drier for an hour to see if that doesn't brighten it up.  I, for one, would
> be happy to come up with a way to get a NYS style hammer more dense without
> lacquer.  Lacquer is tricky and unforgiving in some ways.  I find that when
> trying to build up the hammer from scratch it is important to select the
> right solution for the first application.  Since densifying the felt usually
> needs to be done at the core of the hammer where the felt is already the
> most dense, applications of lacquer tend to seal the felt from further
> penetration by subsequent applications.  You don't get the same effect by
> multiple applications of weak solution as you do from a single application
> of the right solution.  The lacquer has a tendency to build up outside the
> core.  Rather than a graduated density, which I think is desirable, you can
> end up with a hammer that is hard on the perimeter but not necessarily at
> the core.  Applying lacquer from the side of the hammer helps in this
> respect.  On the other side, you can overdo it and apply to heavy a solution
> which can glue everything together and rob the hammer of necessary
> resilience.
> David Love


If necessary I have had good luck with lacquer applications and to compensate for the build up problem I use straight lacquer thinner a few minutes before a weak mixture application to drive the lacquer deeper.  Instinctively any voicing up or down with chemicals feels like I am limiting the hammers potential and life.

David Koelzer
Vintage Pianos
DFW