The Importance of the Finish on a Sound Board

Resin, a principle ingredient in varnish, is considered nature's "master stroke" in preserving the fiber in wood. Wood properly treated has wonderful durability, so a sound board properly treated with varnish helps preserve its integrity. But there are many types and qualities of varnish, each for its own purpose. What follows are a few vital hints in connection with the use of varnish on sound boards.
Keep unused portions of varnish away from the open air as much as possible. Keep brushes perfectly clean, and brush out the varnish rapidly from spare dipping as thinly as can be smoothly done in each coat to be used. Plenty of time must be allowed between coats. This will give the finished product an elasticity of surface it cannot have any other way, will help avoid cracking and consequently will prove almost impervious to moisture.

Sound Board Glue Used in Days Gone By

Hot hide glue is a gelatinous substance extracted from the hides, bones and connective tissues of animals. Its molecules are very fine and are able to link together in very long chains and has a great affinity for other certain types of materials. These types would include leather, cloth and wood. The stickiness of the glue is due, for the most part, to this molecular attraction to itself.
Too high a heat will destroy to a great extent this molecular attraction which destroys this stickiness so important a characteristic of this glue. What heat is too high? Any temperature higher than 145 degrees. A report by O. Linder and E.C. Frost before the 1914 meeting of the American Society for Testing of Materials showed that "overheating glue is found to be weakened by forty to fifty percent."
The Madgeburg hemisphere test, performed in 1650 before the German emperor by Otto von Guercke is illuminating. If we completely exclude the air from between a joint with glue, we are utilizing the force of atmospheric pressure to hold the parts together. It required sixteen large horses to pull apart these twenty-two inch "hemispheres" perfectly fitted together and then pumped free of internal air to create as near a vacuum as was then possible. (Practical Physics, Black and Davis, pp. 101-102.)
Hot hide glue will find its way into the pores of wood and make an absolutely air-tight joint. In the same report by Linder and Frost, it was brought out that blocks of wood glued and tested for the strength of glue required from 1,100 to 1,950 pounds of force to the square inch before the blocks would pull apart. The blocks were clamped together in the "usual manner" in what might be called a hair line joint.
In the successful gluing of a soundboard, namely the edge gluing of the boards to make the panel, the gluing of the ribs and bridges to the completed board and the gluing of the board to the frame or inner rim of the piano, every particle of glue that will squeeze out must be squeezed out so as to permit the actual touching of the molecules of the two parts to be glued together. Further, the greatest care must be taken to have the pressure uniform throughout the lengths of the parts being glued.

Felt and Hammer Making

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 114^th East 13^th 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 19^th 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.

A Noble Art

"A Noble Art" is a book of a series of lectures available from Amazon, dealing with the development and construction of the piano.  In it the author, Miss Smith, leads up to the building of the Steinway piano which she eloquently holds forth as the epitome of piano making.  While this is an attempt to explain the "mysteries" of piano making, the work is here and there marked by observations laden with such views as to distort reality into something imaginary, or at least romanticizing the whole process of the manufacturing process.

It does, however, offer some interesting insights couched in heavenly prose.  Here's an example from the book of what I mean: "In the hour when I saw this (the piano factory), the walls of the factory wherein I stood stretched upward to the grandeur of God's temple; and the wrinkled face of the workman beside me, his eyes resting lovingly and proudly on the beauties of the action before us, became glorified in a priesthood whose majesty he knew not. It is the wonder and pathos of life that they who serve its deepest mysteries -- yes, even the holy of holies -- have no significant initiation, no outward badge.  Their badge is but toil's superscription in the lines of face and form; their initiation but the long discipline of faithful labor.  Theirs is but a matter of regulating a few springs and levers, but the levers are among those which lift humanity."

From her we learn that "the purity of a pianist's tone" depends on how the finger attacks the key.  There is no question that that is the case.  However the piano must be in excellent tune and voiced and regulated well for that to be true.

I applaud Miss Smith's remarkable and earnest study of the piano manufacturing process.  She is justified in holding up the Steinway as the pinnacle of piano design and construction.  Only a few other piano making firms could hold their own against a Steinway back in the late 19th century, which was when these lectures were written.

The Gertz Tension Resonator

FROM THE MUSIC TRADE REVIEW, VOL 40, NO. 9, MARCH 4, 1905, PG 21

Secures Patent This Week Whereby the Tension on the Rim Supporting the Sounding Board of the Piano is Easily Adjusted and the Adjustment Maintained Regardless of Atmospheric Changes.

                        Washington D.C., March 1, 1905.

An improvement patent, bearing the No. 783,781, was this week issued by the Patent Office to Richard W. Gertz, of the Mason & Hamlin Co., Boston, Mass.  It relates to pianos, and has for its object to provide a novel construction whereby the tension of the rim supporting the sounding board may be easily adjusted and the adjustment maintained regardless of the hydrostatic changes in the atmosphere.

In patent No. 658,985, granted to Emil A. Gertz and R.W. Gertz, is illustrated and described a piano in which the rim to which  the sounding board is secured, as usual, is maintained at the proper tension by means of tension members, which pass through the rim and have suitable heads on their ends which engage the outside of the rim (outside of the inner rim – Vince).  The rim in said patent is constructed of a plurality of layers of wood placed with the grain running longitudinally thereof, and therefore the strain on the tension members is across the grain rather than in the direction of the length of the grain.

In order to keep the sounding board under proper tension, it is FREQUENTLY NECESSARY to tighten the tension members to such an extent that the heads on the ends of the tension members are apt to crush the grain of the wood against which they lie and to be drawn into the rim to some extent (Emphasis mine. We are told not to ever tighten those tension members).  The result is especially apt to occur whenever the rim swells any, due to moisture in the atmosphere or otherwise, for it is a well known fact that whenever wood swells or shrinks, the swelling or shrinkage takes place transversely to the grain rather than longitudinally thereof, and any swelling or shrinkage of the rim of the piano therefore causes it to increase or diminish in thickness or width.  Such increase or diminution in the thickness or width of the rim not only operates to increase or vary the tension on the tension members, but frequently causes the flat heads on the end thereof to become embedded in the rim.  As soon as this occurs the tension on the rim is reduced, and it becomes necessary to readjust the tension members (Again, my emphasis) in order to bring the sounding board up to its proper pitch.  It is to obviate this difficulty and to provide a construction in which the head on the end of the tension member will not become embedded in the wood of the rim under any circumstances that Mr. Gertz made his present invention.  This object is accomplished by providing the ends of the tension members with tapering heads, which are received in correspondingly shaped recesses in the rim.  The taper on the heads, while sufficient to prevent the latter from being pulled through the rim, is such that the strain on the tension members is transmitted to the wood substantially in a direction parallel to the direction of the grain of the wood.  With this construction the strain on the tension members will not crush the wood, as is the case where the pressure of the head comes transversely to the grain rather than longitudinally thereof, and therefore there is no danger of the heads becoming embedded in the rim and the tension on the latter relaxed due either to swelling of the rim or to any other cause.

END OF ARTICLE

So it appears that any Mason & Hamlin grand piano made prior to 1905 with the tension resonator present should be checked for tightness of the tension members, but those made after 1905 shouldn’t be. . .

What's real?

"Days pass and the years vanish

And we walk sightless among miracles.

Lord, fill our eyes with seeing.
Fill our minds with understanding.
Fill our hearts with pure intent.

Let there be moments when the holy ghost, like lightning,

Illuminates the darkness in which we walk.

Help us to see, wherever we gaze, that the bush burns, unconsumed.

And we, clay touched by God, will reach out for knowledge and exclaim in wonder,

How filled with awe is this place and we did not know it.”

- Anon.

Piano Moving in 1904

Moving pianos in large cities is a peculiar occupation. To the casual observer, it looks like a good, easy job for a strong, healthy man. There seems to be little to the business except tugging, pulling, pushing and lifting. Estimating the qualifications of a piano mover, one would be apt to demand of him little more than a broad, square pair of shoulders and sinewy arms capable of swinging several hundred pounds of dead-weight. That undoubtedly is the popular conception of the man who makes a success in this line. And it is not altogether a wrong conception for piano movers, as a class, are strapping big fellows with a generous gift of muscle.

But when you go to the bottom of their occupation you find that they must have other qualifications as well. It is a line of work which no one ever learns completely. A man may be an expert at moving pianos and yet every day encounter an angle to the business which will be absolutely new and which will call for the application of much mechanical ingenuity.

In days gone by, when flat buildings were designed and built with the comfort and convenience of their occupants as the dominating principle of construction, the piano mover had a comparatively easy life. In the first place, there were fewer pianos to move. He could devote more time to his work, and as there were few high apartment houses, each delivery was practically a repetition of the one preceding. Then came the modern flat building, with its winding, angular stairway, its narrow doorways and small windows, its elevated parlors and bewildering entrances. And with the advent of this modern building the troubles of the piano mover began to multiply, until today men engaged in this line of work are convinced that if they have any enemies they are to be found in the ranks of up-to-date architects. The designers of apartment buildings have increased the work of the piano mover fully fifty percent, and it is impossible to estimate the number of worries that have been heaped on his head.

Wherever it is practicable a piano is carried from the wagon to its resting place. Three muscular men will literally shoulder the instrument and plod up two, three of four flights of steps with the utmost ease. But where a stairway is too narrow to permit passage, or doors have been constructed on too cramped a plan, the piano mover must resort to other means of transportation.

The block and tackle is the favorite resource of the piano man when an instrument must be elevated from the outside, taken through a front window, or across the railing of a back porch. One end of the rope is hitched either to a chimney or some projection from an adjoining building and with muscular power the instrument is raised to any height desired and swung through an open window with the utmost care. In carrying pianos, the weight is divided between one man in front and two in the rear. Conditions frequently require that the keyboard and front of the instrument be taken off, and in rare cases it has been found necessary to reduce the piano to a skeleton before taking it into an apartment.

It is only within the last two years that the work of the piano mover became so fully developed that it called for the recognition of labor organizers. Up to that time almost any strong, healthy man with an aptitude for lifting could qualify as a piano mover. The intricacies of the work, however, began to multiply with the prevalence of the modern flat building, and the piano movers formed a union, which now has a membership of one hundred and fifty. It is a dangerous occupation, the number of injuries being great. As a rule, these injuries are sustained on stairways. - from "The Music Trade Review" pg. 35 vol. 39 no. 10, 1904.