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Hello,
So many good questions and comments on this threads I don't see what I can
add.
I have made some research to understand why some felt was sold to us to be
"carbonized" while other does not advertise on that.
In fact in the old times, since 1860 or so, there was only machines to clean
the wool from the thistle and vegetal residues (it was even hand cleaned, by
prisoners, was said, before 1860 and the apparition of "the leviathan" a
machine developed by Mr. De Laoureux de Serviers, who lived in SERVIERS, in
Belgium, and this town was the "only" European place for wool washing and
preparation before making cloth or felt with it (till other places appear
near Hamburg in the 1910 ) The wool yet came from south America, England and
other countries as well.
Then around 1880 a chemical process including the use of acid (liquid or
vapor) was used to 'carbonize' the vegetal in the wool. The process gives a
brown color to the wool and then it have to be bleached (with bleach) to get
white again (while may be it can be leaved without bleaching, as find in
some traditional felt cloths.
With a goggle research I have find the declarative papers from the French
"water agency", that our actual wool washers (in washing columns) are using,
as the process is using a lot of water, that is contamined then with dye and
other products and may be recycled or treated.
I asked at the Wurzen factory and had a talk with someone who was kind
enough to tell me that those days all the wool is carbonized to get rid of
vegetal, that is the usual process.
Then some wools are a little yellow, and other are bleached to death (like
the Laoureux hammer felt which is very white). I don't know but I suspect
the lanolin staying within the fiber differ depending of the strength of
these processes.
My question was because I noticed that the white Laoureux felt is making a
scratch noise under the needle even if the elasticity is poor, so I wandered
if the bleaching process had something to do with that.
I've read also a comment from Topper Piano that German hammers are sometime
impregnated with some lacquer, this has not been my experience, but maybe
the heat used (and more if some vapor have been used, which turn the hammer
in stone) while pressing leave us with a felt that give that impression
(particularly with VFG felt it can be noticed).
I was also said that any color or additive added to the felt was
counterproductive in terms of resiliency/elasticity.
Another question : the Piano felts are not treated against moths (generally)
and can be attacked , particularly the softer ones, so we should have some
Cedar or anti moth paper in the boxes where we keep our parts.
If you have find brownish pieces in the old felts that certainly mean they
where not carbonized, or not bleached.
I'll ask that question also to the Wurzen people, about the action of
lanolin in keeping the fiber springiness, but I guess too much lanolin goes
against the felting density (fulling).
I am happy to see that the effort from that felt maker to give us a very
good product are appreciated, and I have them know about it.
We need enthusiasts here, before its too late !
Friendly wishes to all
Isaac OLEG
-----Message d'origine-----
De : pianotech-bounces@ptg.org [mailto:pianotech-bounces@ptg.org]De la part
de antares
Envoyé : mardi 18 mai 2004 22:39
À : Phillip Ford; Pianotech
Objet : Alfred Dolge would smile upon us
Hello Phillip,
I was in the Wurzen factory and I have seen (roughly speaking) how the 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 produced.
These layers of hair are actually the layers in the felted hammers we later
buy.
The layers of hair are put on top of each other until they form a certain
thickness and pieces of these layered wools are put into a fulling machine
where they undergo the process of fulling.
This process of fulling is where the fibers of the wool hairs are being
"interlocked". They thus form the real first mass of felt as this process is
combined with heat and water and shaking.
The secret of the Wurzen factory is that they control this fulling process
to the max and that is why we now have such a high quality felt (again).
If you look at the latest Wurzen AAA quality felt you will notice a 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 chemicals
(as Dale Erwin too described the other day).
The art of getting out the desired colors is the art of voicing. The Wurzen
felt offers, so far, the most interesting palette of colors and, as we all
know, this felt is for sale in America at Ronsen hammers (Ray Negron).
We are now faced with two problems :
we want the hammer maker to make a perfect hammer with this new felt (not an
easy task).
We need to learn again to work with this wonderful felt. As Dale said it :
we should actually only dope these hammers to accentuate some
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
great craftsmanship and artistry.
Alfred Dolge would smile upon us but he is probably busy with other things
André 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 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 tension
can
be achieved during pressing in the outer layers of felt and it can &
will rip
open in the crown. This is the elastic limit of the felt. As the
stretching
of the felt on the outer perimeter happens the inner parts of the felt
are
compressing. It has too because of the stretching of the outer felt, the
triangular shape the felt strip is cut & the hammer press pressure
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 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 than
new hammers. It's hard to know how much of this is different felt and 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 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 have
the sense that the felt isn't really very dense. The felt seems to feel a
little 'grittier' for lack of a better term. And they respond 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 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 nothing
like it was in the old hammers. There really were layers, or at least they
behaved as if there were layers. You could peel one of those hammers like
a grape, if you were so inclined. This is all to say that I'm not sure any
felt available now is like the felt they were using a few decades ago, for
better or worse, and what I'm hearing here is that many people think it's
for the worse.
The discussion seems to concentrate on how hammers are made: hot or
cold pressed, lots of pressure or not, glue at the tip of the molding or
not, etc. There doesn't seem to be much discussion of the makeup of 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 are
many breeds of sheep. They produce wool of different colors, fiber length,
fiber strength, and felting ability. Also, sheep are not the only animals
that produce feltable fibers. Camels, goats, and llamas, among others also
produce feltable fibers with properties different from those of sheep wool
fibers. There's nothing to prevent these various fibers from being blended
with one another (I believe I heard Ari Isaac once mention that he wanted
to try making some hammers with felt that had some mohair in the blend). I
believe that the length and quality of the fibers depends on where on the
animal the wool comes from. I think the best wool is from the chest area
(but don't quote me on that). I can also imagine that the quality of the
wool from a given breed of sheep could be dependent on its sex, its diet,
and its environment. The wool from a male merino sheep eating grass in the
north of Scotland is probably going to be different from that of a 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, and
perhaps bleach them. I don't know much about these processes, but I would
imagine that agressive or excessive carding could break down long fibers,
that excessive washing or washing with agressive soaps could strip
desirable substances off the fibers, and that bleaching could affect the
properties of the fibers (although all of these processes, agressively
done,
would probably make the felt look nice and clean). So, more choices to
make
about how to treat your raw materials.
Now you have your processed fibers and need to felt them. I'm not
clear on how they do this, but pressure, rolling, and perhaps heat are
involved. Once again, choices about how much pressure, how much rolling
and turning, and whether to use heat and how much.
So, there are many choices to make in each step of the process. Each
of these choices will affect the properties of the final
product. Unfortunately for us, I think that the felt properties that would
make the best piano hammers are not the felt properties that most
industrial customers are looking for. Wool that will make a good machine
tool vibration isolation pad isn't necessarily the same wool that will
make
a good piano hammer. And piano hammers make up a tiny percentage of the
felt market. When I was at the Steinway factory I saw stacks of felt 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 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 what
he
considers such a tiny quantity. So, if we're getting hammers with dense
felt without much tension and compression in them, then that may be
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 by
the pressing is what gives a superior performing hammer, then you have to
have felt that is capable of standing up to that process. The outer fibers
have to be able to stand the tension. So, your felt has to be made up of
fibers of the requisite length and strength to achieve this tensile
strength. How the density of the felt would affect the pressing process is
unclear to me. But it seems possible to me that very dense felt might have
a different neutral bending axis, so to speak, as it's being bent over the
tip of the molding, which results in less tension on the outer fibers 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 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 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. To
get the best felt for this purpose, let's imagine that you need chest wool
of a Lincoln sheep raised in a cold climate, not carded or washed too
much,
not bleached, blended with some mohair, and felted to a low density. 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 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
André 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"
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