DRY HEAT DAMAGE
(Page updated August 2020)
If you love pianos, this may be the most important article you ever read.
If you have spent a lot of money on restoring a piano, or even if you are putting it into temporary storage, it is important to think about what conditions it will be kept in. Damp or condensation may cause expensive damage, but dry heat can destroy the piano completely. Recently, I was surprised to see a quite considerable amount of moth damage in a modern piano. Such problems, which used to be commonplace, rarely occur nowadays, but most of us will come across pianos damaged by heat or sunlight. Repairing this damage can easily cost over a thousand pounds, so it is a major concern when trying to assess the value of an old piano, and many are written off. If you had a car worth £100 and the repair estimate was £1,000, what would you do?
OLD, UNUSUAL TUNING DEVICES
Around 1885, Brinsmead made his Patent Tuning Device, which became known as a “Top-Tuner”, because the threaded metal tuning screws in the upright models were on top, instead of the normal arrangement in front.
Many tuners dislike them, but my limited experience is that the tuning is easy to control, and very stable with regular tuning, although replacement of broken strings is sometimes difficult.
Here is my drawing of one of the tuning screws, the cap on the left holds the string in place, and the tuning key slides over that to turn the hexagonal nut. The nut rests on a thin brass collar, which in turn rests against the iron frame. It is a bit like comparing guitar machine heads to violin pegs, and personally, I wish all pianos were top-tuners, but the idea did not survive. Hawkins had made screwed tuning devices around 1801, Mason & Hamlin did something similar in the late 1800s, and Debain incorporated a threaded fine-tuner into some of his instruments, which pressed on the top stringing. Cluesman, Paris, made some weird grand pianos around 1836 which have tuning pins both ends of the strings, and take thirty turns of the key to achieve the same effect as a single turn of an ordinary pin. However this arrangement, in the tenor and treble sections, is simply another fine tuning device, with the main wrestpins unusually placed at the rear end of the piano.
THE NORMAL ARRANGEMENT
Mainly though, we are stuck with simple metal wrestpins like this one, driven into wood, a much stronger version of the same crude principle used on a violin or an old ukulele, with the string wound around it, in this case needing a tool to turn it. I learned my trade in the sixties, and saw the possibility of earning a comfortable living tuning pianos, but by the seventies, the explosion of demand for central heating, double glazing and cavity wall insulation left us all gasping for fresh air, as many people who had shivered through their chilblained childhood were determined to be very warm. This had an enormous and devastating impact on the lives and livings of piano tuners, and led to a situation where huge numbers of pianos that had survived for decades were suddenly untuneable, and were written off as not being worth the cost of repair.
Piano tuning is not a dying art, it is the pianos that are dying!
In the eighties, I assessed the pianos on my tuning round as needing £15,000 worth of urgent repinning work, and that was just dealing with individual loose pins, without doing the whole pianos. Durable old instruments that had remained tuneable, like Broadwood cottage pianos from the 1860s, or Erard grands from the 1840s, were suddenly being written off. People are often horrified at the idea of piano-smashing contests, but when a lovely instrument has already been destroyed by central heating, it hardly seems to matter.
That, more than any other factor, was what made me put more and more time into collecting and filing piano history, because I argued that if we can’t keep the pianos, we should at least rescue what we can of the history from them. As it turns out, this has grown into something that is of benefit to many people around the world, and this website receives thousands of hits every day.
Next time you see a circus strongman lifting a piano, think about the feat of strength that goes on inside a piano. A typical piano may have about 210 strings, each of which bears a tension equivalent to THE WEIGHT OF AN ADULT PERSON. The main problem with many of the pianos was that the wrestpins, (tuning pins) being fixed in wood, were becoming too loose, and huge numbers of old pianos were written off in a period of a very few years.
In early upright pianos, the wrestpins are sometimes found to be in curving lines, so that there is less risk of the plank splitting along the grain, but as the tension and number of strings increased, this became impossible.
Even the concept of “loose pins” is misleading, it is the wood around them that causes the trouble, and it really is quite amazing that the plank puts up with having over 200 holes drilled into it. Amid a confusion of conflicting advice about temperature, humidity, designs of iron frames, the myth of wear actually being caused by the process of tuning, and talk of dishes of water and various other alleged cure-alls, I realised that because the main problem was loose wrestpins, the real answers would lie in testing the pins accurately, and assessing the rate at which they deteriorated. The way to do this was to obtain a sensitive, low-range torque wrench that measured the RESISTANCE TO UNWINDING.
The best tools for the job of testing pins are preset torque wrenches, because the tuner can easily apply a standard test to find the loosest pins on a whole piano without disturbing the majority of pins. A Britool low-range torque wrench with settings down to 20 inchpounds is useful if fitted with a tuning bit, but Britool also make a torque screwdriver, mainly intended for even finer measurement, pictured below.
Another useful application for this tool is in achieving consistent tuning of drum heads.
I started off working with inchpounds as my units, because inches and pounds were familiar to me, but I stuck with them because my projections suggested that natural deterioration often averaged out roughly in the order of 1 inchpound per year, so if the loosest pins measured 10 inchpounds, you would be lucky to get 10 years’ use from the piano, even in ideal conditions.
From 1976 to 1990, I collected a huge amount of data, thousands of readings on hundreds of pianos, ranging from brand new ones still in the showrooms to two-hundred-year-old antiques. By testing pianos that were tuned daily by students at the London College of Furniture, I also confirmed that pianos that were tuned frequently were at no more risk than others, and did not suffer from frictional wear. In the first few years, it became clear that temperature and humidity controls were not the answer, and in order to be worthwhile, room humidifiers needed to consume up to a gallon of water a day to have any significant impact in a large room or small flat. Although low humidity is a factor, it is a relatively minor one, and some of the effect is reversible, but it can result in an increase of up to six times the natural rate of shrinkage.
You think that's bad?...
The most important single issue was the position of the piano relative to the heat source. There seemed little point in publishing hundreds of pages of complex data when the whole situation could be summed up in a single sentence...
Keeping an old piano in direct sunlight, or within five feet of a heater, will almost certainly raise the temperature of the wood to a level where the resin evaporates, causing serious, permanent, irreparable damage. In this danger zone, natural shrinkage is multiplied by up to THIRTY TIMES its normal rate, because the high temperature results in evaporation of the natural resins, and this damage to the wood is not reversible. It should be obvious then that underfloor heating is often the death of a piano. A reading of 30 inchpounds in direct sunlight, or next to a radiator, may well mean that the piano will be untuneable within a year. Since all this is about the deterioration of wood, it applies equally to soundboards, keys, etc., as well as guitars, clarinets, and antique furniture. Strange as it may seem, even where there is a major obstruction between a heater and the piano, the five-foot rule still holds good, with surprising accuracy, and the wrestpins within five feet are still the ones which are most likely to suffer, cutting the remaining life expectancy of the piano to a thirtieth of what it could have been.
By "five feet", I mean 60", not 59" or 61", so if there is a radiator 30” from the treble end, the treble half of the piano will be ruined. The facts are very strange, because man-made systems are still subject to natural forces, and even having a brick wall between the heat source and the pins often has no effect.
Sadly, there are far too many tuners who will use a few loose pins as an excuse to do themselves out of work by writing off a perfectly useable old piano that doesn’t conform to modern specifications.
People often like to display grands in bay windows, but it is unrealistic to think you can regulate sunlight, you must move the piano away. Thermostatic valves on radiators may help a great deal, if they stop the radiators reaching a high enough temperature to cause the problem, but why risk it? Some makers claim that their new pianos are unaffected, and the iron frame in a modern piano should remain quite cold: it dissipates heat, so it probably compensates for a lot of climatic change, however, my research makes it clear that if the iron frame does not feel cold, it is a reliable indication that the piano is having too much heat pumped into it, and will suffer damage.
Perhaps you should take your piano's temperature, and see if it is feeling under the weather!
From what I can tell by modern measurements, the tightest pins hardly alter at all over the life of the piano, and may reduce by less than 1 inchpound per year, even in heat conditions. The weakest areas of grain are the ones that deteriorate most, with the result that the range of variation of readings on a wrestplank will increase with age. If all this is true, we can get a rough idea of the quality of manufacture by extrapolating the original tightness of the best pins, and these are often in the order of 80 inchpounds on a cheap piano, or 120 inchpounds on a top quality instrument.
Without donations, I will be fine, but our collection may not survive for future generations, and it may all end up on a bonfire. If every visitor to this site made a small donation, we would have better displays for our building, and much-improved facilities for research within our own archives. Cheques must be made out to Bill Kibby-Johnson. Foreign cheques are subject to high bank charges, so if you are posting a donation, bills are easier to change without any of your money disappearing on charges.
Reviewing my old tuning records recently, I found that most pianos were at least fifty years old when they became untuneable, but it is surprising that in the seventies, I came across a few fairly new pianos with loose pins, including some made by Berry, Brasted (Challen and Eavestaff). Some brand-new ones, such as Barratt & Robinson, would not even pass a 20-inchpound test, which was worse than many old pianos. Forty years on, some of those Barratt & Robinson pianos are starting to have trouble with loose pins, so they have done better than I expected: others have been less fortunate in central heating.
Others, such as Kemble and Yamaha, measured at least 120 inchpounds, making the task of tuning quite physically exhausting, and requiring the increased leverage of an extendible lever, although the piano should have a long tuneable life. However, tight pins can result in instability in the initial tunings, and if the tuning gets neglected, it may take several visits to settle down again, so to get the best from a good instrument, it needs to be tuned regularly.
When I started to tune my 1879 Challenger piano, it sounded so bad that I just assumed that the pins would be very loose, and being oblong pins, I used the traditional T-hammer. I quickly found that the pins were so tight that I had trouble turning them with this tool, and when I torque-tested them, many pins were over 40 inchpounds – 139 years old and still tighter than some new pianos!
Have you ever worked for a boss who sits and watches you do a job, waits for you to finish, then says "That's rubbish, do it again!"? That's what a torque wrench does. It lazes around in the toolbox while I sweat for hours on a piano, then comes along after the event and says "nineteen of those pins are not tight enough, you'll just have to pull them out and do them again!". The very fact that I put up with such abuse from a small, inanimate object should demonstrate that I have learned, from long experience and detailed research, that…
THE TORQUE WRENCH IS ALWAYS RIGHT.
It's all very well for a tuner or stringer to talk about the length and depth of his or her "experience", but experience is of no value if it cannot be measured. Imagine if a car mechanic looked at a tyre and said "that looks hard enough" when he could simply put a gauge on it, and measure the exact pressure. In the same way, for a tuner to say that a pin "feels about right" is not acceptable, we need a professional means of saying "that passes the 30-inchpound test" or whatever the figure. Most tuners are not even aware of the existence of such measurements, much less experienced in their practical uses.
One of the most wonderful Bechstein grands I have ever played or tuned, expensively restored and repinned, was ruined in a few months by being kept in a constant 80 degrees, not just untuneable, but splitting and coming apart. The appalling discovery I made during my research was that most of the newly-repinned pianos I tested still had a significant number of loose pins. Repinning is least effective on the worst pins, or the weakest area of the plank, so the only reliable answer is to test every single pin as it is replaced. Deterioration in the first few weeks after repinning is also a major problem, and depends very much on the quality of the timber. A few years ago, my old friend Rod Watt, an excellent craftsman, repinned two German pianos, a 1924 Niendorf and an 1892 Bluthner.
The Niendorf (above) had been made with such poor timber between the wars that it continued to deteriorate after repinning, and was soon untuneable again, in spite of all sorts of experiments, whereas the good old Bluthner's plank remained as good as it was on the first tuning.
Loose pins are the principal cause of broken strings, because the extra movement leads to metal fatigue. Various alternative methods have been suggested for dealing with individual loose pianos, but if they involve removing the pin, the risk is that the string will break. My torque research did not show any useful, consistent results for a range of methods of tightening pins, and the only reliable approach was to fit a thicker pin, but that might involve buying a new string. However, it is always worth trying to reset the pin deeper into the plank, or to use the technical term…
“Beltin’ it wiv an ‘ammer”
Many old wrestplanks have a a very thin layer called a CROSSPLY on the surface, but I was taught that the idea of laminated planks (made completely in crossply layers like plywood rather than solid wood) was a modern one, yet here, we see Kirkman boasting a “Solid Plank” in 1872, as if it is something unusual and superior.
IF a designer does his job properly, and makes the tensions even, then…
IF the wrestpins are exactly the same size, and the holes are drilled into the wrestplank to precisely the same size and angle, then…
IF the stringer measures and cuts the wires with absolute consistency, fits the coils equally and neatly, inserting precisely the same amount of wire into every pin, and hammering every pin in to precisely the same depth, then…
MAYBE the ultimate goal can be achieved - such perfection and uniformity of stringing skill that when the piano has been fine-tuned, every pin lines up precisely with the next, and is turned to the same angle. Since this is virtually impossible to achieve, one can assess the quality of work in terms of how near to the ideal the finished product is. The examples above, by Erard, 1881 and Ibach, 1883 show the stringer’s art at its best. The picture below is one of the worst restringing jobs I have ever seen…
So let's assume that I am convinced of the value of torque testing, I still have the task of persuading the man who has been doing superb stringing all his working life on top-quality pianos. Who am I to say "that's not good enough"? Will he be impressed by the fact that I can produce a torque wrench? No, he has never used one, and doesn't see why he should start now! Why should he? In two words, the answer is "Central Heating"! Detailed measurement of newly re-pinned pianos has proved to my satisfaction that there are two major problems which arise with normal re-pinning methods.
1). As a result of re-pinning the whole piano with the same size of pin, those which were the loosest, and therefore the worst for tuning, are the same pins which remain the loosest, because re-pinning in this way is least effective on the pins which need it most. One could discuss the reasons for this in greater detail, major cracks are less common, but softer areas of grain in the wrestplank are the most common cause.
2). There is a kind of "settling-in" period of a few weeks, during which these new pins may gradually become looser. In the picture, the loose pins are randomly placed, as marked by red washers. This may occur with a new piano as well. Cheap old wrestplanks can sometimes take three or four sizes larger than the original pins, and still have problems.
Before re-pinning, the tightest original pins can often still function very efficiently after a hundred years or more, without any need for larger pins, but it is my experience that in order to produce a good standard throughout, the choice of pin size must take into account the weakness of certain areas of the wrestplank, and this requires detailed, meticulous testing and marking of every single one of the original pins before they are removed. Unfortunately, once the old pins are removed, this is impossible and the only solution seems to be the use of a range of pin sizes, rather than a standard size throughout the piano. This begs the question - "How does one decide which size to use, and where?" and this leads to yet another conflict with the conventional way of doing things.
A professional stringer wants to apply the string to the pin, make the correct number of neat coils and, ONLY then, hammer the pin into place in the wrestplank. Up to this point, there is absolutely no way of knowing how tight that pin will be, and if there proves to be a problem, it is unlikely that the string can be removed from that pin and fitted to another, without risking damage to the wire, leading to breakage. The alternative is to wind the pin into the hole with a torque wrench, and check the tightness before applying the string to the pin, but this makes it impossible for the stringer to achieve the high standard of neatness and uniformity that he seeks from his art. Neatness, in this instance, is not just for appearance sake, it also helps to create uniformity in the way that the strings hold in tune. I have no answer to this conflict, but torque testing is certainly the answer when it comes to the replacement of individual loose pins.
Barrie Heaton on the Piano History Forum says "Have you ever reamed out the plank? Then repin, and you can get nice even torque. However, there is also one other factor - the pins themselves: Have you ever measured them? There can be quite a big difference across the whole set, German ones are good but you still get the odd duffer".
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