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I'm saying that if you apply steam to the felt it swells-up as if it had been pressed together with a binding agent.. you call it glue, I am not sure if I would call it glue..


How do you explain the presence of synthetic fibre in the felt (unless I am mistaken)? Synthetic fibre, as mentioned by Del will not felt with wool, so how does it stay together?

my guess is as good as anyone else's guess..

but what i DO know is that traditional, high quality wool felt for piano-hammers, as mentioned by Dolge, should only be made with wool, soap and water..

If I needle a hammer with real wool felt, or steam it, it reacts quite differently than a Yamaha or chinese hammer (my experience with chinese pianos is from the cheap stuff I have seen, which seems to break apart... not sure how to describe it.. not the same stuff as traditional wool felt IMO)


as far as dog-hair, traditional vs. modern material etc..

I believe that since what is deemed a decent grand piano can now be bought with 10,000 dollars, which is a crazy low price, I doubt that manufacturers are going to put the effort and money into higher-quality felt, which might be quite expensive to make, and on such a slight price-tag would certainly raise the price by a bit..


I prefer the rabbit-felt hammers' sound to that of the new renners, and I am not the only one according to feedback I am getting on the net.

To my knowledge no manufacturer has used a “binding agent” either in the felt as it is being made or as part of the hammermaking process. It is not needed to make felt hard and dense; moisture, heat and pressure can do that all by themselves. I suspect what you have found are hammers that were pressed with very moist felt using a lot of pressure and heat.

To illustrate, I once saw a sample of felt in the shape of a hammer—the kind of hammer you drive nails with—at one of the felt manufacturers that was quite dense enough actually do just that; it could be used to drive nails in very soft wood. This density was achieved by extending the felting time and then with a combination of wet felt, high pressure and heat. I don’t know that there was any use for felt this hard but it was an interesting example of what can be done with wool.




Synthetic fibers are added to some felt materials and products as an extender; it is used to lower the cost of the felt or, in some cases, to give the material properties it does not have naturally. The synthetic fibers do not themselves act as binding agents and no binding agents are used in the process. (At least not so far as I have been able to determine; If you have any real evidence to the contrary I’d be interested in who is using them and why.) Depending on the type of wool it can still be felted with up to 70% synthetic fibers. The result wouldn’t be tough enough for piano hammers, though, so when fillers are used they show up in relatively small amounts.




Well, there is a little more to it than that. Chemicals are used to clean the felt and other chemicals are used to speed the felting process. But what you are seeing is the result of “real wool felt” that has been processed in different ways. Some felt makers “felt” the wool more tightly than others. Some achieve the final density by a combination of felting followed by a final pressing to size and shape.

Once the hammermaker gets the felt it can also undergo a variety of different processes. Without microscopic examination I doubt you’d be able to tell just what the felt has gone through between the time it left the felt maker and was inserted into the hammer press.

I suspect what you’ve found is not really the result of “real wool” and “the cheap stuff” is not so much a matter of cost or quality as it is the hammermaking and voicing process. Hammers that are pressed very hard require a certain amount of “pre-voicing,” or needling before they are installed on the piano. Or after they are installed, but in a factory it is often done first. Needling forces the fibers apart, tearing at least some of them. Highly needled felt is not the same as felt that was pressed to a lower density. The hammers become some softer but they are not as resilient as hammers that are pressed with less pressure and heat to begin with. This is true of all hammers regardless of where they are made or the quality (and cost) of the felt from which they are made.




That was a joke….




As I’ve said before, good hammers can be made from inexpensive felt and bad hammers can be made from expensive felt.



The following description on the making of rabbit-felt comes from Wikipedia:


ddf

Hi,

Interesting what you are saying about pressing hammers when wet under high heat..

I must say it does not make much sense to me because intuitively i would imagine that such a felt could not have the mechanical qualities for a wide range of colors from pp to ff

I am lucky in the sense that I deal mostly with antique pianos, and the felt on the hammers is usually put-on by hand, hammer by hammer.. as was done by Erard on their parallel pianos until 1920 or so.. no chance of any hot-pressed felt!

As far as the rabbit-felt and carroting, this is not something which is universally applied to rabbit-felt.

I can prove this by showing you this video

http://www.youtube.com/watch?v=67yq...pZAVp3rrGFw&index=2&feature=plcp

the felt I used to recover the hammers is hatmaker's felt, it is made of rabbit, and perhaps hare fur..

as you can see it is gray-ish just like the original Pleyel felt, but the sound is more percussive because of the type of felting.

the Pleyel is from 1842 and is only partially restored, and not tuned.. this was an improvised video done on my iphone!

I have only just seen this - sorry for coming late to the party. It is interesting from a historic perspective and has the makings of a great thread. I have a few undereducated comments.

ACortot, you are dealing with manufacturers in historic pianos that did things differently almost year to year. They were learning as they went empirically and did not feel the same way about their instruments in 1845 as they did in 1840.

Some of the early pianofortes used leather hammers with a felt reinforcement, then tried combinations of layers of felt and leather, then a few years later only wool felt, many times in layers. I think it might be a huge investment of time to try to do exactly what they did in 1840 and it may not give you the "authentic" tone in the end anyway.

Cleaning, scouring, and processing has changed so often since then. It would be dumb luck to arrive at the same lanolin level in the felt itself, for instance. This would make a huge difference when a hammer is made.

Also, from simple examination of a hammer, one cannot always tell if a single layer of felt is used or if it was multiple layers.

There are manufacturers today who use multiple felt layers that appear the same color. The only way to know the difference is to know the difference. It is not obvious upon examination.

My 2 cents,

the felt in question is similar to the damper felto of the time, curly fibres of very fine diameter felted in all directions and not in layers..

today's felt is mostly layered.

I had a hard time getting some damper-felt made for an Erard, since there is no commercially available felt which comes close to my knowledge, and although the felt was good enough to do the job it did not have the same structure as the original Erard damper felt, which could be pulled-apart from any angle and it would break-up in a similar manner..

from a historical perspective, each manufacturer had his own approach, but Pleyel, having Pape as head of their factory for a period, in my opinion was using the 'Pape' felt, made of rabbit and other fibres, from about 1830 to 1850.. a description of 1844 mentions that one of the hallmarks of the Pleyel sound, apart from the velvety, veiled sonority, is that the pianos kept their tone, as when they were new, for an unusually long time..

the only material which can achieve this is rabbit-felt.. the rabbit felt was noted to never become hard and bright upon repeated use, hitting against the string.

wool felt becomes compacted, leaving hard spots where the string hits the hammer.. Leather becomes brighter in time as well.. only rabbit felt does not..

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.

ddf

yes, opinion is opinion..

I prefer the velvety sound of rabbit.. but I would not choose it to play elton john music for example..

as far as durability, I have been told they last a long time, and I feel that in general there is too much emphasis on durability and not enough on tone..

professional musicians will go to great length to get the sound they want, pro pianists will lug around their own piano and technician and/or have a grand in every major city..

when we deal with the 'consumer' market made-up of non musicians looking for something 'good' but cheap that is another story..

'good is the enemy of great'

let us not forget that these are Steinway pianos made in 1919.. was there ever a better-built steinway from a quality standpoint?... if it is not the golden age it certainly stands among one of the best and most fruitful periods..

Most of the old techniques were abandoned because of cost..

Rabbit-felt is more expensive to manufacture than Wool-felt

the modern hammer costs a fraction of the traditional multi-layered hammer and can be built in a fraction of the time...

the old hammer-method required many different layers of material, applied by hand..

the old cases were built of exotic hardwood, as were the veneers..

to build an old piano today, such as the ones used in the romantic period by Erard and Pleyel, Herz, Pape etc. would cost probably more than a Fazioli..

one only needs to know these pianos to see the sheer amount of material cost and work that went into them

a modern piano is quite simple to build in comparison, IMO.. and standardization has made assembly and repair much easier.. much cheaper..

so I wouldn't shrug the past off so quickly.

I agree Max!