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. 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. 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 ----- Original Message ----- From: "Bill Ballard" <yardbird@pop.vermontel.net> To: <pianotech@ptg.org> Sent: July 16, 2002 9:21 PM Subject: Re: Shellac vs. lacquer As I understand it, reinforcers do three things, one after the other depending on the dose. First they coat the fibers to slow them down, thus dampening their elasticity. Next they glue adjacent fibers together, where these are close enough to have their gap bridged by the resin, again hobbling the felt mass's natural elasticity. And third, and most disastrous, they fill in the air space within the felt mass. I think David, we have a similar vision of what's happening inside the felt mass. I don't think that the density of the hammer changes significantly until the dosage has done the first two stages, and is turning what used air space into solid resin. That's when the compressibility is non-existent. (There is no air space in which the compression can occur.) In the first two stages, I don't think the amount of solids is enough to affect the density of the felt mass. But the flexibility of the felt mass is nevertheless affected. Coating the fibers, and gluing them together at point of adjacency will definitely stiffen the felt mass, requiring more force to get it to compress. All this talk of embalming hammers would lead one to wonder why anyone would ever want to dope a crown. Well, with NY Steinway hammers, unless your pianist likes their piano warm and fuzzy, it's inevitable. You can firm up the shoulders all you want, even including under the strike point. But the hammer and the string are a pair of springs, and the best sound comes when the reach their maximum deformation simultaneously. Power and projection from a NY Steinway hammer will not emerge until the strikepoint fibers have been stiffened (and their bending under force slowed). And if I'm obliged to stiffen, I'd like to stiffening resin to have its own elasticity to contribute to the hammer/string event.
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