---------------------- multipart/alternative attachment Hello Phillip, I was in the Wurzen factory and I have seen (roughly speaking) how the=20= felt is made. It starts with a heap of selected wools mixed together. This wool goes into a 'carding machine' where layers of hair are=20 produced. These layers of hair are actually the layers in the felted hammers we=20 later buy. The layers of hair are put on top of each other until they form a=20 certain thickness and pieces of these layered wools are put into a=20 fulling machine where they undergo the process of fulling. This process of fulling is where the fibers of the wool hairs are being=20= "interlocked". They thus form the real first mass of felt as this=20 process is combined with heat and water and shaking. The secret of the Wurzen factory is that they control this fulling=20 process to the max and that is why we now have such a high quality felt=20= (again). If you look at the latest Wurzen AAA quality felt you will notice a=20 higher density of the fibers. Yes, you can actually see it. But most of all, you can actually hear it. The tone is one if totally natural elasticity without any use of=20 chemicals (as Dale Erwin too described the other day). The art of getting out the desired colors is the art of voicing. The=20 Wurzen felt offers, so far, the most interesting palette of colors and,=20= as we all know, this felt is for sale in America at Ronsen hammers (Ray=20= Negron). We are now faced with two problems : we want the hammer maker to make a perfect hammer with this new felt=20 (not an easy task). We need to learn again to work with this wonderful felt. As Dale said=20 it : we should actually only dope these hammers to accentuate some=20 percussiveness, not to "totally fill the tub and throw the babies in". This is an interesting period where we are again offered felt made with=20= great craftsmanship and artistry. Alfred Dolge would smile upon us but he is probably busy with other=20 things Andr=E9 Oorebeek On 18-mei-04, at 22:07, Phillip Ford wrote: >> To all Hammer Heads >> In the previous thread I was trying to convey the way I see that = a >> hammer >> is made & if you followed that then you see that I have a definition=20= >> of >> tensioned felt in mind. However what I failed to articulate clearly = is >> that Tension >> & compression go hand in hand in the hammer pressing process. >> As I stated, & piano hammer makers can tell you, that too much=20 >> tension >> can >> be achieved during pressing in the outer layers of felt and it can &=20= >> will rip >> open in the crown. This is the elastic limit of the felt. As the=20 >> stretching >> of the felt on the outer perimeter happens the inner parts of the=20 >> felt are >> compressing. It has too because of the stretching of the outer felt,=20= >> the >> triangular shape the felt strip is cut & the hammer press pressure=20 >> itself. >> ... >> Regards >> Dale Erwin > > And in a previous post I was trying to convey the idea that the > makeup of the felt itself is important, and that perhaps the makeup of=20= > the > felt that is available now is different from what it was in the good > American hammers of the past. The old hammers look and feel different=20= > than > new hammers. It's hard to know how much of this is different felt and=20= > how > much is just age. Also, as TP pointed out, if you file these hammers > you'll often find embedded dirt and junk in the felt. Stick a needle=20= > in > one, and you'll sense that it feels different to the needle than a new > hammer would. You can push the needle in without much effort, and I=20= > have > the sense that the felt isn't really very dense. The felt seems to=20 > feel a > little 'grittier' for lack of a better term. And they respond=20 > dramatically > to even a single needle stitch. Also, you'll hear people referring to > layers in hammer felt when talking about new hammers. My experience = is > that new hammers don't really have them. I haven't tried the new=20 > Wurzen > felt hammers yet, but I have tried the slightly older Wurzen felt > hammers(such is used on Hamburg Steinway I believe), and while the > impression of layering is more noticeable with these hammers, it's=20 > nothing > like it was in the old hammers. There really were layers, or at least=20= > they > behaved as if there were layers. You could peel one of those hammers=20= > like > a grape, if you were so inclined. This is all to say that I'm not=20 > sure any > felt available now is like the felt they were using a few decades ago,=20= > for > better or worse, and what I'm hearing here is that many people think=20= > it's > for the worse. > The discussion seems to concentrate on how hammers are made: hot=20= > or > cold pressed, lots of pressure or not, glue at the tip of the molding=20= > or > not, etc. There doesn't seem to be much discussion of the makeup of=20= > the > felt itself, other than is it Wurzen or not. I get the impression = that > people think that sheep are sheep and felt is felt (the way that most > people think apples are apples - if you asked most people how many > varieties of apples exist, they would say two; red delicious and = granny > smith. They would be astonished to learn that there are hundreds of > varieties of apples - we don't see any of them because of the nature = of > business in this country, not because of the nature of apples). There=20= > are > many breeds of sheep. They produce wool of different colors, fiber=20 > length, > fiber strength, and felting ability. Also, sheep are not the only=20 > animals > that produce feltable fibers. Camels, goats, and llamas, among others=20= > also > produce feltable fibers with properties different from those of sheep=20= > wool > fibers. There's nothing to prevent these various fibers from being=20 > blended > with one another (I believe I heard Ari Isaac once mention that he=20 > wanted > to try making some hammers with felt that had some mohair in the=20 > blend). I > believe that the length and quality of the fibers depends on where on=20= > the > animal the wool comes from. I think the best wool is from the chest=20= > area > (but don't quote me on that). I can also imagine that the quality of=20= > the > wool from a given breed of sheep could be dependent on its sex, its=20 > diet, > and its environment. The wool from a male merino sheep eating grass=20= > in the > north of Scotland is probably going to be different from that of a=20 > female > merino sheep eating soybeans in California. So, there are many = choices > available when making a selection of fibers to be felted. > After you choose your fibers you have to card them, clean them,=20= > and > perhaps bleach them. I don't know much about these processes, but I=20= > would > imagine that agressive or excessive carding could break down long=20 > fibers, > that excessive washing or washing with agressive soaps could strip > desirable substances off the fibers, and that bleaching could affect=20= > the > properties of the fibers (although all of these processes, agressively=20= > done, > would probably make the felt look nice and clean). So, more choices=20= > to make > about how to treat your raw materials. > Now you have your processed fibers and need to felt them. I'm=20= > not > clear on how they do this, but pressure, rolling, and perhaps heat are > involved. Once again, choices about how much pressure, how much=20 > rolling > and turning, and whether to use heat and how much. > So, there are many choices to make in each step of the process. =20= > Each > of these choices will affect the properties of the final > product. Unfortunately for us, I think that the felt properties that=20= > would > make the best piano hammers are not the felt properties that most > industrial customers are looking for. Wool that will make a good=20 > machine > tool vibration isolation pad isn't necessarily the same wool that will=20= > make > a good piano hammer. And piano hammers make up a tiny percentage of=20= > the > felt market. When I was at the Steinway factory I saw stacks of felt=20= > for > hammers. It looked like a lot of felt to me, but was apparently > insignificant to the supplier. I was told that basically Steinway has > to choose one of the suppliers standard felts because the amount of=20 > felt > they buy is a miniscule percentage of that makers output, and that the > maker wouldn't be bothered to make felt to their specifications for=20 > what he > considers such a tiny quantity. So, if we're getting hammers with=20 > dense > felt without much tension and compression in them, then that may be=20 > because > the hammer maker is working with the only materials available to him. > If a hammer having lots of tension and compression built into it=20= > by > the pressing is what gives a superior performing hammer, then you have=20= > to > have felt that is capable of standing up to that process. The outer=20= > fibers > have to be able to stand the tension. So, your felt has to be made up=20= > of > fibers of the requisite length and strength to achieve this tensile > strength. How the density of the felt would affect the pressing=20 > process is > unclear to me. But it seems possible to me that very dense felt might=20= > have > a different neutral bending axis, so to speak, as it's being bent over=20= > the > tip of the molding, which results in less tension on the outer fibers=20= > when > the hammer is pressed. This would be a desirable thing if you're = using > felt without much tensile strength - perhaps another reason for using=20= > high > density felt. But if this supposition is correct, then to achieve = high > tension in the outer fibers when pressing the hammer, you might have=20= > to use > lower density felt. > To make an old style hammer I think maybe you want wool with = long > fibers that hasn't been manipulated too much and not pressed too hard.=20= > To > get the best felt for this purpose, let's imagine that you need chest=20= > wool > of a Lincoln sheep raised in a cold climate, not carded or washed too=20= > much, > not bleached, blended with some mohair, and felted to a low density. =20= > Can > you imagine anyone in the world being willing or able to supply such a > thing in 2004? Forget it. In 1904, probably. But we've made 100=20 > years of > 'progress' since then. > > Phil > > > > Phillip Ford > Piano Service and Restoration > San Francisco, CA > _______________________________________________ > pianotech list info: https://www.moypiano.com/resources/#archives > > friendly greetings from Andr=E9 Oorebeek Amsterdam - The Netherlands 0031-20-6237357 0645-492389 0031-75-6226878 www.concertpianoservice.nl www.grandpiano.nl "where music is, no harm can be" ---------------------- multipart/alternative attachment A non-text attachment was scrubbed... Name: not available Type: text/enriched Size: 10570 bytes Desc: not available Url : https://www.moypiano.com/ptg/pianotech.php/attachments/cf/ff/e6/fe/attachment.bin ---------------------- multipart/alternative attachment--
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