Touchweight: or, "Why is my piano so hard to play?" by Kendall Ross Bean
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You may have noticed that some pianos are easier to play; others require more effort. Some pianos feel even and smooth from note to note, and yet others seem like each key requires special treatment to produce an even tone. The reasons for this are various, including softer or harder hammers, heavier or lighter action parts, action parts that are pinned more tightly or loosely, newer parts vs. older ones, whether the piano's action is properly adjusted (or regulated) or not, the design of the instrument, room acoustics, and even the weather, but it all comes under one heading: Touchweight.
Most pianists know that pianos vary widely in touch. But few actually understand why. Some have noted that newer pianos seem to have stiffer actions, and older ones that have been played a lot, often have easier actions. A piano that has had new hammers installed may now be more difficult to play than it was before. Conversely, one that has had the hammers reshaped or filed many times may have a feather light action. Pianos that have been stored in humid environments, or that have not been played for a while, may have tight action centers (the little pivots and hinges on which the action parts rotate or swing). Many vintage pianos, including Steinways made in the first half of the twentieth century, may have developed a problem technicians call vertigris, where for some reason a greenish substance grows in the action center over the years, causing it to bind. Pianos with vertigris problems often have very sluggish actions. And many pianos just come out of the factory with relatively tight centers: it is expected that the new owner will go through the process of breaking in the instrument (playing it often enough or long enough so that the centers loosen up). On some pianos, though, this can take an inordinately long time: Often the piano tuner or technician must be called in to take care of action centers that were pinned too tightly (or loosely) at the factory.
Many times, an action that is too stiff or heavy is the result of not just one, but a number of different problems: Hammers that are too heavy, action centers or keybushings that are too tight or have too much friction, misaligned action parts that are rubbing against each other, the wrong leverage ratio between critical action parts; -even too many lead weights in the keys, which may have been installed either at the factory, or at a later time, in an effort to compensate for the other problems mentioned above.
At PianoFinders, we will typically look at all the areas in an action that could be contributing to a touchweight problem, before deciding on a plan of action. Otherwise, there is a possibility of actually making the problem worse by compensating in one area for something that should have been corrected in another. For example, inexperienced piano technicians will often attempt to address an action that is too stiff or heavy by adding more leads to the keys. If the original problem was that the hammers were too heavy or the action centers were too tight, and these areas are not addressed first, adding keyleads will only compound the problem by adding additional inertia to the system.
Why touchweight is important
If you are doing a lot of practicing, or playing, or are attempting to become proficient on the piano, it is important to understand some basic issues about touchweight. Too light or loose an action will not enable you to build up finger strength properly, and will make it difficult for you to subsequently play on other pianos that may have stiffer actions. On the other hand, too stiff or heavy an action will lead to fatigue, make your practicing less rewarding, and may ultimately lead to serious muscle injuries, as it unfortunately has for many pianists. An action that has an inconsistent touchweight from note to note will make it difficult for you to learn proper shading and dynamics, or to play evenly, and will also make it harder for you to play on other pianos besides your own.
Definition of touchweight and how it is measured
Basically, touchweight is very simple: It is the amount of pressure required to depress a key on a piano. To measure how much, gram weights are placed on the end of a key until it begins to go down. Today, piano touchweight is pretty much universally measured in grams, but in the past was often specified in ounces. The ounce is really too coarse a unit for measuring key resistance (there are approximately 30 grams in an ounce); piano regulating manuals I have seen from early in the 1900's, for example, called for a touchweight of approximately 2 ounces. This is almost 60 grams, which is a fairly heavy touch. Most piano manufacturers today aim for a touchweight of around 50 grams. -Not that they often achieve it on any consistent basis, however.
When you depress a key on a piano, you actually are physically lifting the hammer (felt which strikes the strings) and associated action parts, against gravity. The part of the key your finger pushes on is designed to travel downward approximately 3/8". The hammer, however, travels approximately 1 7/8" upward, against gravity. Thus, the hammer travels 5 times as far, or 5 times as fast, as the end of the key does. Because of the nature of the leverage (it is technically a "distance multiplier"), this means that any weight on the hammer end of the mechanism is multiplied at least 5 times at the keytip, where your finger pushes on it. I say "at least," because in actual practice this ratio may range anywhere from 5 to 7 times. (This is actually more true of grand pianos than verticals; however, in general the same principles still apply. Vertical pianos tend to have lighter or easier actions than grands because the hammer moves rather more sideways than upwards when the key is depressed.) (Maybe we should find another word besides "depressing" to describe what we do with the keys.)
Note that the definition of touchweight above mentions nothing about the amount of, or any, sound being created for a specific pressure on the key. This type of touchweight measurement only gauges the minimum pressure required to get the key to go down. This is, however, a very useful starting point, called static touchweight. Dynamic touchweight, or the actual pressure required under varying playing conditions, is more difficult to measure, for it takes into account numerous additional factors that tend to complicate the equation: how loudly or softly the piano is being played, how fast certain notes are being played or repeated, whether the sustain pedal is up or down at the moment, etc.
In addition to these complications there is an additional one: Human perception. For instance, two similar pianos may have the same static touchweight, but one may give out more sound than the other for a given key pressure, due to different densities of hammer felt or a number of other reasons. The instrument that gives out less volume will generally be perceived as being harder to play, or requiring more effort, because the pianist "gets" less for what they "give."
Some historical background
Pianos in general have grown progressively larger and more powerful over the past couple of centuries, with thicker and heavier strings under higher tension. As artists over the years have demanded instruments with more volume and power from piano makers (in order to be able to project to the extremes of large halls in which they were playing), larger and heavier hammers (and action parts) have been required to strike the strings with sufficient force to create that desirable "big tone." This, however, has created quite a few new problems for pianists, who now have to work harder to play these instruments.
In recent years certain piano makers have been manufacturing instruments with even heavier, denser hammers; and action centers (the pivots on which the hammer assemblies swing) that are pinned more tightly than was previously considered acceptable. The objective of moving in this direction was to achieve a yet fuller, more powerful tone, but at the same time, numerous reports have surfaced of pianists suffering debilitating muscle injuries after practicing or performing on these pianos.
Piano makers usually install lead weights in the keys (called keyleads) to counterbalance the weight of the hammers, particularly on grand pianos. If you look at the hammers on a piano (the felts that strike the strings) you will notice that hammers in the low bass are larger and heavier than those in the high treble, and that the hammer size and weight tapers, proportionally, as you go from one end of the keyboard to the other. More lead weights are usually needed in the lower registers where the hammers are larger, fewer in the higher registers where hammers are smaller.
(To see these lead weights, you can depress a key in the low bass register so that you can see the side of the neighboring key, e.g. the wood part of the key that is under the plastic or ivory keytop. Usually you will see a number of small round lead weights embedded in the side of the key. These are easier to see in the low bass, usually, because there are more of them per key in that register, but on many pianos you can actually see the keyleads on all the keys.
In recent years, to compensate for the additional weight of even heavier and denser hammers, several piano makers have been installing additional lead weights in the keys. This alleviates the problem in one way, but aggravates it in another. Lead weights will indeed counterbalance a heavy hammer, but will also add inertia: actions with a large quantity of lead in the keys feel sluggish, especially when trying to play fast repeated notes, trills or in any other situation where the key has to move quickly.
To address this inertia problem that results from adding lead to the key, some European and Asian piano manufacturers, instead of using a large number of lead weights, use an additional spring in their actions (called a whippen auxiliary spring). This spring stores energy from the hammer's return, so that when a key is depressed, the spring, instead of key leads, helps the key to go down against the hammer's weight. The drawback to this type of system is that unless it is well-designed and kept in a state of good adjustment, repetition ( the action's ability to quickly repeat notes) can be adversely affected since the spring resists the return of the key (or hammer) to its rest position.
Some fine quality vintage German pianos I have worked on have neither whippen auxiliary springs nor much (if any) lead weighting in the keys. The owners of such instruments usually are very pleased with the touch, and say they definitely prefer the touch of their pianos to that of new high quality instruments that do use a considerable number of lead weights in each key.
A further contributing factor is that many brands of U.S., Asian and European pianos arrive new on the showroom floor with relatively "soft" hammers, as it is assumed that the felt will pack down where the hammers strike the strings, and become "work hardened," with playing. The result of the felt becoming compressed in this fashion is that the piano's tone gradually becomes louder and brighter over time. If the sound is going to get brighter, the reasoning goes, then it's better to start with a fairly soft hammer, as a tone that is a little on the mellower side seems to be more acceptable to most people than one that is a little too bright.
However, the manufacturers seem to have overcompensated in many cases; pianists often complain that they can't get any tone out of the piano: the hammers, they say, are like "cotton balls" and they must overexert themselves to get any sound at all. Hammers do indeed "wear harden," or "break in" somewhat with time, but often not as much as is anticipated, and much of the time nowadays the piano technician has to help the 'breaking in' process along with a generous amount of dope or lacquer on the hammers. (Doing this however, is frowned on in some parts of the technical community: many piano technicians feel it is better to have a properly made hammer to begin with, and that the use of lacquer or other chemicals as a stiffening agent, after the fact, may make the piano's tone brighter, but ultimately robs the instrument of important expressive capabilities.)
Japanese piano makers, in the past 20 or 30 years, have gained substantial ground over the U.S. manufacturers in the marketplace, because the Japanese pianos seem to arrive on the showroom floor better prepared: Hammers are sufficiently hardened to create a pleasing tone without inordinate effort, and actions are not so stiff that it is a chore rather than a pleasure to play the pianos.
In 1891, the House of Steinway brought the the famous Polish pianist Paderewski to America to show off his playing (and their pianos). In Paderewski's memoirs, he mentions having problems with the Steinway piano because he was accustomed to playing European pianos, which had fairly light actions. Compared to those European pianos, the Steinway had a very heavy touch. Of course, the Steinway piano also had heavier strings under higher tension than the European instruments, and was capable of a more powerful tone. But Paderewski found the Steinway action almost intolerable, because of the amount of effort required to play it. The problem was ultimately solved by Steinway providing Paderewski pianos with actions specially "lightened" or adjusted to his preferences.
Incidentally, this "customizing" has been Steinway's procedure, and that of other makers of high quality pianos, for accommodating a number of top-flight pianists over the years. The bulk of the pianos that go out to the dealers for general consumption, of course, do not get this special treatment, as it is not ultimately known who will be playing them, and it is assumed that adjustments or corrections will be made if the action is not agreeable. However, as much of this "final prep" is today left up to the dealer, and as he must pay out of his own pocket, in most cases, to have it done, it often gets neglected, especially if the customer isn't knowledgeable about what to expect from the piano, or persistent in requesting adjustments.
Realistically speaking, it would be prohibitively expensive for a piano manufacturer to spend all the extra time devoted to the artists' instruments on a piano that was not intended for such critical use, or where the person ultimately buying the piano may not appreciate or even notice all the additional effort and expense. To do so would probably require that high quality pianos cost two to three times what they do now, and they are already pretty expensive. The problem arises, though, when pianos arrive at customers' homes in a state of adjustment far below the acceptable standard. Most people who are not experienced pianists, and even some who are, are not familiar enough with what should be expected, to know when there is a problem. They may feel like something isn't quite right, but do not really know where to start, or how to describe the problem. And often, if the piano's touch is heavier or stiffer than is acceptable, or is inconsistent from note to note, they simply assume that that is the way the piano should be; after all, it's supposed to be a high quality piano, and the manufacturer supposedly knows what he is doing.
This problem is not completely the fault of the manufacturer. Even if a manufacturer is able to put the piano in top condition at the factory, different environments to which the piano will be shipped, the settling of new felts, and the shrinking or swelling of new wood will inevitably undo much careful factory adjustment and regulation. It is anticipated that most new pianos will need re-regulation within a year of being shipped to the dealer.
A certain segment of the piano teaching profession has, either inadvertantly or deliberately, contributed to the problem in several ways. Piano teachers, particularly, it seems, those specializing in training child prodigies and competition winners, have discovered that if their students practice on pianos with heavy actions, they get a better "workout" and develop more finger strength. These teachers will often choose or recommend a piano for their students that has a "stiff" action. Essentially, the piano here is being regarded as a weight training machine. There is indeed an element of truth to this point of view, but when carried to extremes can be abused: some teachers appear to believe that if a little resistance is good, then more is even better.
It is true that students who do practice on "stiff" actions generally perform better than students who don't, (at least for the short term, before muscle injury often occurs). -Especially if much of the time they are performing on Steinways and other big-name pianos that frequently have "heavy" or stiff actions, or heavy hammers, or tight centers, or a considerable amount of lead in the keys. It is true that it is easier to adjust to a light-actioned piano if you have been practicing on a stiff action, than to cope with a stiff one after practicing on a lighter action (as Paderewski unfortunately discovered). Since there is virtually no way to predict with any degree of certainty what kind of instrument a student might find himself performing on, and since touch presently varies so widely on pianos, teachers have pretty much resigned themselves to the notion that "the student must practice on an action stiff enough to allow them to cope with any instrument they might encounter." As there are some inordinately stiff and poorly adjusted instruments out there, one can see where this mentality inevitably leads: students being encouraged to practice on progressively heavier and heavier actions, and manufacturers actually requested, by teachers, to produce pianos with even stiffer actions. These particular teachers, in addition, have developed, and teach, piano techniques that favor "stiff"-actioned pianos, and with which their students often feel "out of their element" on light-actioned instruments.
The objective, unfortunately, is to win the piano competition, not protect the students' physiology. The sad truth is that several "stiff action" techniques currently being taught are inherently dangerous; teachers who advocate such techniques later wonder why so many of their students are experiencing muscle and tendon injuries. Yet to them, there often seems to be no alternative, given the current lack of uniformity of touchweight among pianos.
A complicating factor, though, is that it takes additional labor and expense for piano manufacturers to regulate piano actions to the proper touchweight, and keep them there for any length of time. New felt installed in the action can be expected to settle for several weeks or months after leaving the factory. Even though piano makers have begun to use "breaking in" machines to help compact new felts, pianos continue to go out of adjustment rapidly due to felt settling during the first year or two of use, and a piano out of adjustment is always more difficult to play. On top of this, action parts installed at the factory tend to be pinned together on the tight side in order to compensate for future wear; it is assumed that they will become freer with use. Many times, however, they don't loosen up, at least not without some help from the piano technician. Another difficulty, as previously stated, is that there no real way to predict where a particular piano will end up. Some locations have humid climates, others dry. Action parts will tend to bind more in humid environments due to swelling of wood and felt; dry climates tend to have the opposite effect. And, just like the tires on a car, piano hammers that are new have more "tread," (and thus weigh more) than used ones that have many "miles" on them and/or that have been reshaped several times. All these factors contribute to making a new piano action far heavier or stiffer than it needs to be.
If the touchweight on your piano is not what it should be, or what you desire, touchweight adjustments can be performed to make it the way you want. Before doing touchweight adjustments, however, checks should first be performed to ensure that the the piano has been properly regulated (i.e. each note on the piano has been adjusted to the proper factory settings) and that there are no problems with the action, such as parts rubbing against each other, or action centers (pivots or hinges) that are too tight.
Here are some simple tests you can perform to see whether your piano's touchweight is within proper limits.
How to measure Touchweight on your piano:
You dont need an expensive set of gram weights to measure your pianos touchweight. You can do it easily, and with as much accuracy, using common coins.
For this test, you will need a set of gram weights for measuring between one and 70 grams, or barring that, a set of pennies and/or other coins. Below are listed some of the Gram weights of commone US coins.
Using Coins Instead of Gram Weights Coin Weight penny (pre 1982)* 3 grams penny (post 1982)* 2.5 grams penny (1982)* May be either 2.5 or 3 grams nickel 5 grams dime 2.5 grams quarter 5.5 grams *Apparently some time in 1982, the US mint attempted to economize on the cost of making money by cutting the weight of its copper coins, effectively getting a free penny for every five minted.
Touchweight measurements are extremely useful for a number of reasons. For example, a person may be concerned whether the touch of a piano is too light or too heavy, or whether it is even and consistent from note to note, or whether the piano is giving them a good enough workout to build muscle strength. Finding out a what a pianos actual touchweight readings are can also help pinpoint problems and conditions that may exist somewhere deep in that labyrinth of 6 to 10 thousand moving parts called the action.
Gram weights sets are available from piano supply houses. However, most of them we tried had accuracy problems. Weighing them with a pharmacist's scale, we found them to be heavier than marked by as much as five grams per set. We solved this problem ultimately by drilling holes in the weights to remove some material.
How to perform the test: Get a dozen or so nickels. Tape a stack of 6 or 8 together (30 or 40 grams) and use the rest individually (5 grams apiece) for fine adjustment, along with a couple of dimes (2.5 each). You can also use pennies, but the weight will vary according to the date minted (consult chart, above). Using different combinations of all the coins should enable you to measure differences as small as ½ gram. For most purposes, however, an accuracy of within 2 or 3 grams should be adequate.
Depress the right, or sustain pedal, and hold it down. Place about 50 grams worth of coins or weights on the end of the key. Do this carefully; dont inadvertently push down or you may get a false reading. With light rapping (see inset) the key should slowly start to go down. If it goes down too easily or quickly use fewer coins or weights. If it wont go down at all, or is really sluggish even with the thumping, use more. You are looking for a slow but steady downward motion. When youve found out just exactly how many coins it takes, add them all up and figure out the number of grams using the chart. Dont worry too much about getting it too exact the first few times. You will become more adept the more keys (and pianos) you test. The important thing is to use the same technique for each key (and piano). In other words, if you thump on one, thump on all of them, and with the same kind of thump.
Breaking inertia
Sometimes it take a little extra help to get the key moving to begin with. Many piano technicians, when measuring touchweight, will thump or rap the piano under the keybed with the fist or palm of the hand. Other technicians accomplish the same thing by playing a key near or next to the one being tested. This may seem to some people like "cheating" - yielding a reading that is actually a few grams less than what i really takes to depress the key. However, in real life piano playing the depressing of a key is usually accompanied by a wealth of vibration from strings, soundboard, pedals and other keys being played, so there may be legitimate reason for this practice.
A reading of 50 grams is about standard. Depending on the piano, however, it may be considerably more or less, anywhere from 30 to over 70 grams. Note that the key may not go all the way down. That's O.K. There are additional factors that come into play when the key is about halfway down, and we are not really concerned with them here.
Actions measuring an average of below 45 grams per note would likely be considered "light." Actions that "weigh off" at 55 grams or above are generally considered either "stiff" or "heavy." (And sometimes a little of both.) Both excessively light or excessively heavy actions will be more difficult to control than a properly weighted action. Sometimes a single piano will exhibit both conditions: a touchweight that is too light on some keys and too heavy on others. Consistency is important: a difference of more than a couple of grams between neighboring keys can be felt by most pianists.
Touchweight is usually measured with the sustain (or right) pedal depressed, to take the weight of the dampers out of the system. If you desire, you can also measure how much additional weight the damper system adds. (If you do, however, remember that the dampers do not come into play until the key is at about 1/2 of the way down, unless they are out of adjustment) But for now, keep your foot on the pedal.
You will need to test several keys to get a fairly good idea of where your pianos touchweight is, and, of course, the more keys you test, the more accurate your results will be. In our shop, we routinely weigh off every key for upweight (see below) as well as downweight. The two measurements are then used in formulas to help pinpoint problem areas.
For comparison, Steinway specifies that for their model, S, M & L pianos, the downweight should taper from 50 grams in the low bass to 47 grams in the high treble, and the upweight should be at least 20 grams. This would yield a difference of between 27 to 30 grams.
Note that it is O.K. in their book to have an upweight higher than 20 grams, but not lower. A higher upweight means a faster key return, and for a given downweight, less friction. There are practical upper limits, however. It is possible to have too little friction in an action. When there is too little friction, parts become loose, wobbly and don't do their job as well. Typically there will be a range of acceptable friction, for a given piano, depending on a number of different factors, including who's playing the piano and what they're used to.
Upweight is the amount of weight the key will lift back up from its depressed position. This measurement, along with the "downweight " measurement, can help us pinpoint touchweight problems, such as whether an action is sluggish because of binding parts (friction), or whether it's hard to play because some of the parts (like hammers) are too heavy.
With the key in it's "down" position, see how many grams you can place on it and still have it return to it's "up" position. (Keep the damper pedal depressed; if the weight of the dampers are helping the key to return you will get a false reading) Usually this measurement should be around 20 grams (or about 4 nickels).
If there were no friction, upweight and downweight readings would be virtually the same. The difference in the readings is due to friction in the moving parts. When you depress the key, you have to overcome both friction and the weight of the moving parts in order to lift the hammer. When you release the key, friction is still there, offering resistance now against the keys return. Friction isnt particular: it works in both direction. The weight of the hammer, on the other hand, wants to go in one direction only: down, toward gravity. These unique qualities of friction and weight allow us to separate the two. The difference between the upweight and the downweight can be therefore be regarded as a representation of the amount of friction in the action.
For now, it is not necessary to understand where all the friction comes from, but only that there are acceptable and unacceptable amounts, as far as the pianist is concerned. It is normal for a piano to have a certain amount of friction. Usually 20 to 30 grams difference between upweight and downweight readings is considered "normal."
In general, readings can be interpreted as follows: If the difference between upweight and downweight is high (i.e. more than 30g) there is probably excessive friction somewhere in the action: some parts are probably too tightly pinned or something is rubbing. If the difference between upweight and downweight is low (i.e. less than, say, 20) it probably means the friction is low: some parts may be loose or worn, or need repinning.
If downweight and upweight are both high (i.e. downweight over 50 and upweight over 20) it usually indicates there are some heavy parts in the action somewhere, (often the hammers). If downweight and upweight are both low (significantly under 50 and 20, respectively) it usually means the action parts are light: the hammers may have been replaced with new, undersized ones, or may simply have been filed many times. This latter condition is often found on older pianos, along with old, loose, worn pivots, accounting for their light, effortless feel.
The following tables should help you see the relationships between upweight and downweight.
| Downweight | Upweight | Sum (D + U) | Difference (D-U) | Meaning |
|---|---|---|---|---|
| High | High | High | Normal | Heavy Hammers orother parts |
| High | Low | Normal | High | High Friction |
| Low | High | Normal | Low | Low Friction |
| Low | Low | Low | Normal | Light Hammers or other parts |
| Downweight | Upweight | Sum (D + U) | Difference (D-U) | Meaning |
|---|---|---|---|---|
| High 65 | High 35 | High 100 | Normal 30 | Heavy Hammers orother parts |
| High 60 | Low 10 | Normal 70 | High 50 | High Friction |
| Low 38 | High 32 | Normal 70 | Low 8 | Low Friction |
| Low 40 | Low 10 | Low 50 | Normal 30 | Light Hammers or other parts |
As you can see, there is a pretty direct correlation between the sum and the heaviness of the action parts; and also a direct correlation between the difference and the amount of friction.
These are not the only combinations. For example, you could have a situation where the Downweight and Upweight were both high, as in the first row of the table, but where the difference was also high (that is, compared to the manufacturers specifications). Say the downweight was 70 grams (considered high), and upweight was 30 (also considered high). The difference, 40, would indicate that the amount of friction was high as well.