The Art and Science of Piano Touch Design and Improvement
Transforming the touch of old and new pianos with computer analysis, physics, a good dose of pianistic experience, intuition, craftsmanship and microbalancing.
Apart from the tone a given piano has, the touch, or spielart, is its primary defining characteristic when played. Whether you feel drawn to a piano when you play it, or repelled, has a great deal to do with the touch. This is not necessarily unique to pianos: different guitarists, for example, may prefer a guitar with "light" action, or a "heavy" action. Pianists sometimes also use the term "action" to refer to the touch. An amazing thing happens when the touch is perfectly suited to a piano player's taste: they often describe it as though the piano "disappears" from in front of them and it's just them and music. Some pianists describe it as feeling like the piano is almost playing itself. It's happened to me many times on different pianos and is truly a joy to experience.
It stands to reason, then, that a piano restorer needs to give a great deal of thought and attention to the touch of a piano when it is restored, particularly if parts are being replaced. There are many, many shops out there today happily replacing action parts with little or no understanding of the many complex interactions between individual and combined leverage ratios of the keys, wippens, hammer shanks and damper levers; the effect of friction on the touch; the correct use of leading in keys; the effects of mass and inertia in the hammer and keys when the key is played at different volumes, etc., etc.
The result is that, sadly, there are many heartbroken piano owners who, after spending thousands of dollars having their piano restored, are extremely disappointed with the touch of their piano. Often piano technicians who have been restoring for many years have studied little about the science of touchweight, yet happily replace action parts on a routine basis.
Here is one such example where I was called in to correct the disastrous result of new parts installed by a very highly regarded technician with many years of experience. The piano was a 1975 7 foot Steinway Grand, known as a Model B, which had the disparaged "Steinway teflon action" and needed all parts replaced. The technician, noted in his community as a Steinway expert", and wishing to do the "right thing", ordered new parts from the Steinway factory and proceeded to install them. As an extra measure of dilligence, he even moved a few leads in some keys to locations he thought would improve the balance of the key.
Here are the results. The blue line is "downweight", the amount of pressure in grams that is required to push a key down. The green line is "upweight", the amount of weight a key can lift, and is to some extent a measure of how quickly a key will respond under your finger for re-striking. The red line is called "balance weight" and tells the restorer how the key will balance if no friction is present. Needless to say, this piano is a disaster at this point, despite the fact that it has brand new, factory parts. Below is the touch after it was corrected in my shop.
And here it is after I corrected the problems. The fun thing about this type of very thorough & scientific touch design is that very few technicians have mastered it, and we can often significantly improve the touch of even brand new, high quality pianos (there isn't really the time or budget for this type of work in the typical factory process)
