Back before the Great Depression
of 1930, felt and hammer making in the United
States was arguably at its zenith. I think most of us are familiar with, or at
least seen and/or heard, that type of vintage hammer. If you have serviced early twentieth century
pianos, you no doubt have come across hammers that I speak of; ones that feel
soft, yet have the power of a much harder feeling hammer, and we wonder how
such a hammer could have that kind of power and dynamic range and yet feel so
soft. I don’t care who makes hammers presently,
none of them, in my opinion, stack up to those vintage hammers of yore.
One of those hammer makers from
by-gone days was the piano hammer division of the American Felt Company which by
the 1920’s had factories in NY, Chicago, and Boston. As an aside, the old NY American Felt Co.
building which was located on 114th East 13th
Street , NY, has now been turned into condos! They are selling the units starting at
$900,000. What a deal! The building has 12 floors and 41 units
(google AMERICAN FELT 114 EAST
13TH STREET NY - Demsker Realty to see for yourself!).
J.G. Childs, then foreman of the felt
factory in Chicago, delivered an address on felt and hammer making at the
Chicago chapter meeting (a.k.a. Divisional meeting) of the National Association
of Piano Tuners in November, 1924. The
following is the account of that address as found in the Tuners Journal of
January 1925:
“For a great many years prior to
the latter part of the 19th century practically all hammer felt used
in this country was imported, although there was a certain amount of manufacturing
done here with the idea of making entirely satisfactory merchandise. This culminated in first prize being given at
the Vienna Exposition in 1873 to American made felt and later, in 1878, felt
from this country received the grand prize in Paris . This naturally brought more attention to the
felt made here, with the result that large orders were placed and felt became
more generally known throughout our country.
As it became better known it was universally accepted, for the
realization came to piano manufacturers that felt was being made in this
country that was unsurpassed by any in the world.
“It is interesting to know of the
care and the numerous details that are necessary in the selection of the wool,
the making of the felt and all of the steps to the final covering of the
hammers for the factory.
“First of all, wool for this
purpose is selected from all sections of the world, coming from Australia ,
South America , Cape
Colony , and parts of the United
States .
But of all the wool from these various sources only from five to ten
percent of it can be used for the making of hammer felt – the cream only – as
hammer felt requires long staple, strong, healthy stock and no other will do.
“I have mentioned ‘healthy’. This is a much more important item than one
would think, but, after all, wool is an animal fiber and its quality depends
not only upon breeding but upon the condition of the animal. If a sheep is sick during the period of wool
growth or if a heavy drought occurs, it will naturally interfere with the
growth of the wool during that period of growth. This wool, of course, will break in the
section represented by that growth and cannot be used for the work required of
it. In addition to this, the wool must
be resilient. It must have a proper
number of kinks to the inch. It must be of the proper diameter, as wool that is
too coarse will not make the fine hammer felt required nor can we use wool that
is too fine as it will be too readily cut through by the strings of the
piano. In order to insure these
conditions being met, each batch of wool is thoroughly tested in the laboratory
to see that it meets the specifications.
“This selected wool is next
thoroughly scoured with warm water and the finest of soap. It is run through several washings to
eliminate all the grease, sand and dirt, and later it is subjected to
hand-picking to remove the burrs and tar specks so the finished product will be
white and clean.
“It then goes through the felt
mill where it is first run through the ‘picker’. This mixes the several varieties which go to
make up a good blend and starts the process of combing out the fibers so they
may be laid with the run of the sheet.
This process of combing and mixing is carried further by means of cards,
which is in reality a multiple combing process.
As the wool emerges from the card it is in the form of a thin film,
which is deposited upon a moving belt.
On this belt the wool is built up, starting at the bass side of the
sheet and gradually increasing the width of the lay-out until the entire sheet,
approximately sixty inches in width, has been deposited on the belt. In doing this, it can readily be seen that
the bass end has been made much thicker and has been tapered off to a thin treble.
“Right at this point is where we can
make up the sheet with a heavier tenor or with any other special instructions
that the customer may desire. The
lay-out made here will naturally be reflected in the finished hammer. The batt, as it is then called, is run
underneath hardener rollers – which, by means of vibrated motion helped by heat
and moisture, interlock the wool fibers and harden this soft, downy batt into a
firm piece of hammer felt. However, this
hardening process has really affected only one side, so this sheet is taken off
and put onto a rehardener – which hardens the other side.
“The sheet, which has during this
period been, approximately, thirty feet long, is then cut up into smaller
sheets, approximately five feet square, and is put through the process known as
fulling. This is, in reality, a
shrinking process – which locks the fibers more closely and shrinks the whole
sheet. It is accomplished by large
hammers suspended from a crossbeam, which thump away at this felt until it has
been reduced to a sheet approximately three feet square.
“This process is helped very
materially by warm water and a clear soap solution – and is carried on for over
half a day. At the end of this time the
sheets are taken out, washed free of the soap and the water extracted. Then attention must be given to the treble
end. This generally must be very
brilliant and to obtain this brilliance, the trebles must be re-fulled by hand
in order that they may have the special touch which the customer may desire. Following this, the sheets are pressed out to
remove any heavy wrinkles, sanded, trimmed to an even size, inspected, and they
are then ready for the hammer shop.
“The hammer shop, the Boston
Piano Supply Company, on receipt of the hammer felt, again inspects it to see
that it meets the specifications outlined by the customer. The sheets are then laid aside and held for
the respective customers, as they represent, as nearly as it is humanly
possible to control felt, the touch requested.
“When an order is received the
sheets are taken to the cutting bench, where they are stripped by hand in long
cuts, running from the bass to the treble, and inspected again. These strips go to the covering department,
where the wooden moldings are first set into the press and covered with the
under felt. Upon this the strip of top
felt is then stretched and held in place for the number of hours required for
the glue to set properly. It is
desirable to leave the hammers in the molds no longer than is necessary, just
long enough to complete properly this stretching process, to eliminate the
outer skin which other processes would leave upon the completed hammer. It is our ambition to deliver a hammer which
requires very little tone regulation, and this is always in our thoughts, as we
realize it is a great assistance to the manufacturer.
“The hammers are then taken from
the molds and the rough edges of the hammer felt trimmed off. The amount of felt trimmed off the edge is
carefully gauged in the endeavor to leave the same amount of felt on each side
of the hammer so that it will be properly balanced. After this, the whole strip is sanded off and
the hammers are cut apart. The hammers
then go in trays to the wiring machines and from that point are bored to the
scale, pitch (angles), and size of boring the customer specifies. There is one more inspection made before the
hammers are finally packed, then the package is marked with the customer’s
scale number and sent out.
“You will readily realize that
through these many processes there are opportunities for variation; that the
least thing in the start of the felt through the mill will have its effect upon
the finished hammer in the hands of the tone regulator. It is therefore our aim to watch the details
of felt manufacturing with the utmost care, in order that a uniform product may
be attained.
“The very nature of wool itself
makes it difficult to hold to the absolute accuracy of touch that some people
may demand and, for that reason, many questions have been asked about tone
regulating. I can only say to you that
this is a subject on which I will not attempt to talk, but that you, as tone
regulators, know that you cannot pick a hammer to pieces and produce a soft
mushy hammer and still get satisfactory results. You, of course, must needle hammers – but
when you do so, for the good of the hammer do as little needling as you
can. Every time you stick a needle into
that hammer you are bound to cut some of the fibers and that loosens the
tension which prolongs the life of the hammer to quite an extent.”
<End of article>
Addendum: One of the detrimental effects the gluing process has on
hammers made today, is the enormous amount of heat the glue requires to set up. This is done in order to cut down on
production time. Instead of hours in the
caul as the glue hardens, it now takes mere minutes. But now because of the
amount of heat they use, it affects the felt negatively in that it loses
resiliency. The hammer maker gains in that it shortens production time, but quality suffers.