unfortunately no-one makes this felt anymore.. although as mentioned Steinway and Dolge, in a historic period which was very good for piano sales and piano quality, also exploited the rabbit-fur to make hammers..
today, the cost would outweigh the sales generated perhaps.. so I don't think we'll see it soon.. although the sound is certainly good, and in my opinion it is the sound that Chopin preferred.
Cost is certainly going to be one factor but not the only one. We may not see rabbit fur used to make hammers for modern pianos because it may not work all that well in modern piano construction or in the modern piano itself. And it will be extremely expensive and time-consuming to find out. Reliable sources of supply—in sufficient quantities to support continuous production—would have to be located. Real-world tests would have to be conducted. Felt makers would have to [re]learn how to work with the stuff. And when the felt is finally available hammermakers have to [re]learn how best to press the final hammers.
Finally, when we’ve reached this stage of the quest we can begin the real work of testing the hammers on real-world modern pianos and with real-world modern pianists and listeners. One sample is not enough on which to base a marketing strategy. Will the new hammers stand up to a million blows in the test machine? Will they prove superior in blind A – B testing? Will they find market acceptance? At any step along the way we may find out why those early builders abandoned the material in favor of the all-wool felt in use today in which case all that research investment will have gone for naught.
I give those early pioneers of the piano industry a lot of credit not just for inventing or developing the materials and technologies that made the piano what it ultimately became but also for having the wisdom and courage to abandon materials and technologies that did not work all that well. (We could use some of this in today’s industry!) And this may be one of those things left behind as the development of the piano pushed ahead. Unfortunately those builders were not always as forthright in documenting the things that failed as they were with touting the things that ultimately worked.
There is a tendency in these discussions to portray the things done historically as inherently better and the things done today as inherently less good. Techniques and materials evolved as the piano evolved. Sometimes—Steinway’s introduction of the continuous bent rim, for example—changes were made simply for manufacturing expediencies to reduce the cost of manufacture. Other changes—such as the transition to metal framing—were made because the builders of the time considered a particular approach or mechanism to be superior to what came before. Looking back it can sometimes be difficult to tell the difference.
There also seems to be a tendency among the advocates of early instruments to lump all modern practices together and condemn, or at least strongly criticize them, as a class. Hammermaking seems to be one of these areas. Modern hammers are all the same and they are all bad.
The video linked to early in this is presented as an example of just what is wrong with modern all sheep’s wool hammers compared with early hammers made with (probably) some combination of sheep’s wool and rabbit fur. I might point out, though, that the recording is not the best; it does not exhibit the best qualities of either hammer selection. It certainly doesn’t clearly demonstrate to me that the so-called “rabbit fur” hammers are clearly superior. So we are left wondering if what we are hearing really demonstrating the tonal characteristics of either hammers at their best.
I would also argue that the Renner hammers used are probably not the best hammers to bring out the best tone qualities of an early Steinway Model A. To say, “I put new hammers on my piano” is a lot like saying, “I put a new car in my garage.” It tells us something, but not much. And it doesn’t tell us much more to say, “I put new Renner hammers on my piano.” Are those hammers light or heavy? Dense or resilient? Were they pressed with lots of heat and pressure or were they cold-pressed with low pressure? What were the characteristics of the felt? What was the shape of the felt strip? What was the moisture content of the felt when it went into the press? Was the felt pre-pressed? What kind of underfelt was used? What was the shape of the caul? How long was the press cycle? Was the felt cut to a straight taper or a progressive taper? Going back even further, was the felt heavily felted or was it lightly felted and pressed to shape?
The knowledgeable technician will be aware of these differences and will understand their various effects on the tone quality of the instrument in question. He/she will understand that an early Steinway will have a relatively light and flexible soundboard assembly, a relatively low-tensioned scale—for a “modern” piano—and that a piano with such scaling will call for a rather light hammer that was pressed with little or no heat and with relatively low pressures. Any other hammers put on this piano—the heroic voicing techniques of the world’s best voicers notwithstanding—will not produce a sound anything like that of the original. They can be voiced to give the piano a sound that is very nice and pleasant to the ear but it will not be the sound the original builders heard.
I would take this comparison much more seriously if the so-called “rabbit fur” hammers were paired with, say, a Ronsen hammer of comparable size pressed with Bacon felt in the same hammer caul using relatively low press pressures. These hammers, at least, would come close to the mass, density and resilience characteristic of the early Steinway felt hammers.
I am very interested in better understanding the techniques and materials used by the early builders. Their experiences and the knowledge they gained went on to form the basis of the so-called “modern” piano. As modern technicians we are often remiss in failing to adequately understand the technological history of the instruments of today. Our work and our sense of voice suffer as a result of our ignorance of the past.
I wish we had stronger links to that past in the form of viable new pianos that were built with a greater sensitivity to the musicality of that past. I would like to see the piano buyer of today have the option to play and purchase new instruments with aesthetics and voice that were at least similar to something a composer such as Chopin might have seen and heard when he sat at the keyboard. Instead we are all too often subjected to atrocities such as the one I found myself walking out several years back in which some “pianist” was pounding out some barely recognizable piece by Chopin on an overly bright and harsh [well-known modern concert grand] with such force his butt was lifting off the stool. Yes, I understand such music can be played on modern instruments with great sensitivity but I’d like audiences to have the opportunity to hear it played on instruments that are some closer to the original.
At the same time I’m not prepared to accept that every material and every technique used by early builders was necessarily the best and only way to build great pianos. They may have been the best available at the time and they may well be the best and only way to approach a restoration project but these things do not necessarily translate over well to the modern instrument.