Dampp Chaser Pads – Before and After

Here are some photos of Dampp Chaser pads on a piano I serviced today.

I thought you might find it interesting to see the quality of mineral deposits That the pads can collect.

Surprisingly, the pads still wicked water, but I changed them anyway.



Notice the water line just rising on the right pad.

Relative Humidity

Relative humidity (RH) is a term that piano owners are concerned with because too much or too little is not good for a piano, being made mostly of wood. Excessive humidity can cause metal parts to rust, and wood to swell. Too little humidity in the air and the wood parts can become dry and brittle, and crack or split, and the glue joints can fail.

As piano technicians, we advise that the piano be kept at 42% RH, but it’s actually the wide swings that can cause more damage.

RH can be a difficult concept to grasp, as witnessed by a recent exchange I had on a piano tuner’s forum where some posters were actually quite angry with me for saying that cold air can be more humid than warm air.

I understood their reaction becasue this is counter intuitive; common experience says that cold winter air is drier than warm summer air.

Before explaining my comment, let’s take some time to discuss exactly what relative humid is.

What is Relative Humidity?

Air can hold water. Hot air can hold more water than cold air. Relative humidity is the amount of water in the air, relative to amount of water the air can hold.
See Wikipedia article HERE

Consider an air mass that has a constant amount of water in it, at different temperatures.


The fraction of Actual Water to Maximum Possible Water is clearly higher in the cooler air.

In other words, cooler air has a higher relative humidity than warmer air with the same water content. Counter intuitive, but true.

Take a look at the data I recorded in a simple experiment. I took a hygrometer, which measures temperature and relative humidity, and put it outside on a warm day. I recorded the temperature and humidity and then brought it inside our air conditioned home. If the cooler air conditioned air, did indeed have less moisture than the outside air, then common knowledge says the cooler air should be drier.


Clearly the cooler air was more humid. (Any error in the exact RH measurements is moot since we are looking at the relative measurements, not the absolute measurements.)

Here are photos of the hygrometer outside in the warm air, and inside in the cool air. Time between photos: about 15 minutes.



Air Conditioned Air

Let’s consider the case where we use an air conditioner to cool down the outside air before it enters a home.

For this situation, we must discuss Dew Point.

Dew Point is the temperature at which the air has been cooled so much that, if the temperature goes lower, the air will not be able to hold the current amount of water, and the water will condense out of the air. We can see this water as dew on the cool morning grass after a cool night.
See Dew Point.

Air conditioners have a drain pipe to export the condensed moisture outside, when the air is cooled below the dew point. Just because AC units have this drain pipe, does not mean that the air will always be cooled below the dew point. Let’s consider the situation where an air conditioner is used to cool outside air, but the air is not cooled below the dew point.


In this case, it is easy to see that, for all inside temperatures lower than the outside temperature, the cooler air inside the home will always be more humid than the outside warmer air, if the inside and outside air contain the same moisture.

But what about when the AC unit cools the air below the dew point and condensation occurs?


In this case, there is a point of equal RH where the air is cooler, has less absolute moisture, but has the same RH as the warmer outside air. Any place in the home that is above that temperature, will have more humid air than outside. Lower temperature areas will have drier air. Again, counter intuitive.

The implications of this data have to do with our possible misconceptions with respect to RH.

It is true that pianos are recommended to be kept close to 42% RH, and that swings in humidity are not good for pianos.

But with this new information, some interesting conclusions regarding maintaining a piano’s RH can be deduced.

For example, if a piano is in an air conditioned home, keeping the piano close to the AC unit with the idea that the colder air will be drier and therefore protect it against the outside humid air, may actually increase its RH instead of lowering it.

Similarly, piano owners concerned that leaving their pianos in a cold garage over the winter will dry it out, can be relieved knowing that the cooler garage air may actually be more humid than the warmer inside air, even if the furnace has a humidifier. (There is a chance of wood damage if the air gets below freezing; the moisture in the wood may freeze and expand.)

I was told this stuff by a friend of mine who is an accomplished high end piano rebuilder and technician, and also a mechanical engineer.

When he first told me, I was confused because it went against my common knowledge. But because of my technical training, he was able to easily explain to me why this was true.

I hope that this article, with the links to Wikipedia, and the graphs I produced, will make it easier for you to understand this subject as well.

My Grateful Experiences Tuning Pianos on Prince Edward Island.

This might be an inappropriate post, as it can easily be interpreted as bragging. I can only temper that by explaining the reasons why I’m posting it, hoping that they will help put the post in a more modest light.

Also, I will try to list all the factors that led to this situation, including the ones beyond my control, hopefully reducing any “get rich quick” quality that may be viewed in the post.

First, the facts. In the next three weeks, I will be tuning pianos on Prince Edward Island, a small island province in Canada. Due to events I will explain shortly, I find myself about to tune 8 pianos a day for three weeks, at $150 each. The total revenue generated will be approximately $18,000.

I know some people may scoff in disbelief – I am, just looking at it that number myself.

The reason why I am posting this, is that I am very grateful to find myself in this position and I want to share it with others. Also, some people out there may be interested in making money tuning pianos and I want to qualify how this happened, so that they do not have unrealistic expectations.

There are only two elements that made this happen; opportunity and ability.

Here is how the opportunity presented itself.

About 9 years ago, a lady named Cecelia Bell from PEI contacted me. She found me on the internet and wanted to learn how to tune her own pianos. I couldn’t come all that way for one student, so she suggested she try and find me pianos to tune. She did.

That was the first blessing. Cecelia has been a God send, calling all my customers every spring and fall and booking appointments for me.

The 2nd opportunity presented itself when we tried to sell our farmhouse, the one we bought to stay in, while tuning on the island.

First, the agent couldn’t sell it, so we decided to try and sell it ourselves. I planned to fix it up one spring, but would need time. I told Cecelia that I would have to raise my prices 50% so that I could create some free time. (I was hoping people would choose not to tune their piano with me because of the price increase.)

What happened was that the vast majority of people were fine with the new price.

That was the opportunity. Now I had to deliver. Also, because we did not want to stay long, I had to book all these tunings close together with limited time. So, I had to produce high quality tunings efficiently.

This is where I feel the Go APE method has served me well. With it, I am able to tune a piano within 75 minutes with good results. PEI’s climate is temperate, so regularly tuned pianos are not too demanding. Another blessing.

In addition to the speed of the tunings, the quality has allowed me to keep my customers happy and rebooking.

Finally, the Go APE method uses a low impact technique (NSL analysis) and Double String Unisons to help me develop good stability and unisons, allowing me to tune 8 pianos a day without getting too tired. Some days I may even do 9 or 10 without much more fatigue.

For sure, this situation has fallen into my lap, and for that I am grateful. Even discovering and developing the Go APE method seems, at times, to be a stroke of luck.

I hope other people who have studied the Go APE method with me have had similar experiences.

If so, please share them in the comments section.

The Painted Piano

I found this at Westend Piano Rebuilding Shop in Montreal that is owned by my friend, Doug Yeats – Piano Rebuilder/Tuner/Technician.

Full Front View

Front Panel Detail 1/4

Front Panel Detail 2/4

Front Panel Detail 3/4

Front Panel Detail 4/4

Left Side

Left Side Detail. Those are little googly eyes glued onto the piano.

Right Side

Right Side Detail 1/2

Right Side Detail 2/2

Key Cover Detail 1/3

Key Cover Detail 2/3

Key Cover Detail 3/3. Yes, that’s painted.

Key Cover Open. That’s the real keys.


Top from behind

Error in Stretch Methods

I have developed what I believe to be a very accurate method of producing consistent stretch that creates pure P11/P12/P22 and even P19 if we are tuning a Small Scale piano. (Small Scale pianos are pianos whose F3F43 and A3A4 octaves can be tuned to a pure 4:2 and a pure 6:3 simultaneously.)

But this beat speed window method can’t be used in the extremes because the beats are too fast (treble) or too slow (bass), so I use a different, less accurate/precise method.

For the treble I just listen to the P8 (octave), P12 (octave plus fifth) and P22 (triple octave) below and try to get them to sound as clean as possible.

For the bass, I listen to what Virgil Smith called, “The Natural Beat”. There’s no good science to prove that when playing a bass octave, there is a beat produced at the fundamental of the bottom note if the octave is not clean, but that’s what Virgil said he did, and that’s what I do.

If this method is not as accurate or precise as the beat speed window method, I still think it is appropriate because the error is so small.

For example, consider the Railsback curve, shown below, that shows the sharp treble and flat bass of a piano tuned by a “fine tuner”.


Now, let’s consider that the green line represents the “perfect” stretch, or at least the P12/P22 stretch produced by my beat speed windows.

Pure 12:22 stretch

Now let’s consider that my stretch method in the extremes, is not as accurate. Once I begin using that method, there will be error.

Minor error using inaccurate method in extremes only

However, if I was to use an inaccurate method from the beginning, like just listening to octaves, the error would start closer to the center, and the accumulated error would be huge once we would get to the extremes.

Major error using inaccurate stretch everywhere

Looking at the above curve reminds me of what my tunings used to sound like before I started using beat speed windows for stretch. I could never get the treble and bass to sound clean enough for my ear.

How Good is an Electronic Piano’s Tuning?

There are so many good things to say about electronic pianos.

  • They’re easy to carry.
  • They have many sounds.
  • They can be hooked up to a computer.
  • They can be used as a midi controller.
  • They can be used with headphones so you can practice at night.

But, “They don’t have to be tuned” is not one of them.

A piano that does not have to be tuned, implies that the piano is already in tune.

In all my years as a piano tuner, I have been looking for an electronic piano that is in tune. Almost every electronic piano I check, is so badly out of tune, that I can use any electronic piano after I give a 20 hour course in aural piano tuning, as an example of how badly electronic pianos are tuned, and the beginners who take my classes, with their barely learned aural skills,  can tell.

We shouldn’t say, “They don’t have to be tuned.” We should say “They can’t be tuned, but they should be tuned!”

Many aural piano tuners tune the octave F3 to F4 first, setting each interval size so that they fit with each other. One criteria for equal temperament is that the major thirds increase in beat speed smoothly and evenly.

Listen to this recording of a Roland electronic piano. The first recording is of the major thirds from F3A3 to C#4F4. The second recording is filtered around the beating partial of each major third. You can easily hear how bad the tuning is. The major thirds vary wildly from progressive.

I have added a graph of the beat speeds so you can see, as well as hear the changing beat speeds.

I offer to score aural piano tunings that people send to me, and this one scored 55%. The minimum to pass is %80.

Roland Electronic Piano. Major Thirds. Unfiltered.

Roland Electronic Piano. Major Thirds. Filtered.

Graph of Beat Speeds.
The beat speeds should be within the green lines.


Also, listen to the first beating major third. The beat speed actually starts at 7.8 beats per second, but by the end of the interval, it has risen to 10 beats per second!

Electronic pianos have many benefits. But being in tune is not one of them.

How to Tune Appropriate Stretch

This is often an elusive goal; how much to stretch the treble and bass so that large chords sound good.

Many aural tuners do it by feel; they just tune each octave more or less wider, and hope the end result is pleasing. I think it’s possible to get a feel for how much is too much and how much is not enough, but it takes a very long time; you only know if the final result is appropriate after you’ve tuned a whole piano. Then you have to wait until you tune another whole piano to try something different. And trying to remember the feel or sound of each octave you tuned and repeat or do something just a little different is almost impossible, unless you are gifted with something akin to perfect pitch.

Personally, being a more technical person, I have never liked that approach. I wanted a method that allowed to get the exact same stretch each time, and also allowed me to change the amount of stretch, if I wanted.

I believe I have developed just such a method. It uses Beat Speed Windows; listening to two beat speeds – a slow one and a fast one – and tuning a third interval that beats between these slow and fast beats, that make up the beat speed window.

One step that is required to use this method is to aurally measure the inharmonicity of the piano you are tuning. It is possible. I use the check notes for the 4:2 octave and listen to the size of the 6:3.


Example: A3A4

1. Tune a pure 4:2. To do that, we make the beat speed of F3A3 equal the beat speed of F3A4.

F3A3 = F3A4

F3 is called a Check Note.

Check Note Theory:

The definition of a pure 4:2 is that the 4th partial of A3 must be the same frequency as the 2nd partial of A4.

A3(4) = A4(2)

We use the check note, F3.

Playing F3A3 puts the 5th partial of F3 very close to the 4th partial of A3. This Coincidental Partial is close to the note A5.

F3 is tuned lower than that which would produce F3(5) = A3(4) which would produce no beating at A5. We would call that a pure M3, but we set F3 to be lower than that which would produce a pure F3A3.

Since F3(5) is lower than A3(4), there is beating. And what’s more, that beating is a measure of how high A3(4) is from F3(5); the faster the beating, the higher A3(4) is from F3(5)

Now, when we play F3A4, we also have a coincidental partial at A5 because F3(5) and A4(2) are both close to A5.

And what’s more, the speed of F3A4 is a measure of how high A4(2) is from F3(5).


if F3A3 = F3A4


A3(4) and A4(2) are both high from F3(5) by the same amount,

and therefore, they are the same frequency (or very close to it),

A3(4) = A4(2)

This is the definition of a pure 4:2.

NOTE: The check note is always two octave plus a major third below the coincidental partial. (1)

2. After tuning the pure 4:2, we listen to the different beat speeds produced by the 6:3 check note.

In the case of the A3A4,
the 6:3 partial is where A3(6) and A4(3) are found.
A3(6) and A4(3) are both close to E6.

In case your harmonic series theory is weak, here are the two harmonic series’ above each note:

A3: A3 A4 E5 A5 C#6 E6
A4: A4 A5 E6

From (1), the check note is two octaves plus a M3 below E6, which is C4.

So, we listen to A3C4 and C4A4.

If A3C4 = C4A4, then we have a pure 6:3.

Here are the possible sizes for the 6:3, once we have tuned a pure 4:2, and their respective inharmonicities, which I call Octave Scale. Note that each octave you tune can only have one inharmonicity or Octave Scale.

Aurally Measuring a Piano's Inharmonicity.001

After we know the piano’s inharmonicity, we can use beat speed windows to tune an accurate temperament, and also produce a consistent and appropriate stretch.

For example, on small scale pianos, where the octaves can be tuned as pure 4:2 and pure 6:3, we can have a stretch the produces pure 11ths (octave plus fourth), pure 12ths (octave plus fifth), pure 19ths (two octaves plus a fifth), and pure 22nds (three octaves) all at the same time, and all tuned by using beat speed windows.

I have not written a book on this method but I am open to producing one. Since it would be such a small production, the price would be high. What would you be willing to pay to have me write such a book?

Your other option is to have a personal one on one skype lesson where I teach this method to you live. The cost for that is $100 per hour (2016. Subject to change. CONTACT ME to confirm pricing). I estimate the lesson would take two hours.

I look forward to hearing from you.




1) Learn how to use the extremely accurate Go APE system. 

2) Use bisecting beat speeds windows to produce accurate and precise ET and stretch. 

3) Understand Stability. 

4) Develop your “Tuner’s Ear”; the ability to filter out all unwanted noise and hear beats clearly. 

This method is appropriate for beginners and experienced tuners. 


Two Sessions:

8am to 12pm, $350USD.($440CAD)

1pm to 5pm, $350USD.($440CAD)

Both sessions, $595USD.($740CAD)

These workshops will be given by Mark Cerisano, RPT, who has been teaching piano tuning and repair to hundreds of people since 2006. Read more and get free video lessons and resources at HOWTOTUNEPIANOS.COM

Electronic Piano On Trial

As some of you may know, I provide a temperament analysis service. (For more information, CLICK HERE) The first one is free.

One of my subscribers sent me a recording of the temperament on his electronic keyboard. You can read and hear the interesting results HERE.

FREE Meeting – Piano Tuning

You are invited to a free meeting where I will be presenting some of the elements of my aural piano tuning method I call the Go APE method. It was developed to provide an Accurate, Precise, and Efficient way for beginners and experienced tuners to tune pianos aurally. It is easy to follow but demanding on the specific skills needed to tune a piano to a high standard.

Here are the details:

WHERE: Ottawa Pianos, 1412 Bank Street, Ottawa, Ontario.
WHEN: Wednesday, April 20th. 7pm – 9pm. (TOMORROW!)

Just show up.

This is a regular meeting of the Ottawa Chapter of the Piano Technicians Guild.

The Piano Technicians Guild is an invaluable resource for anyone wishing to advance their skills, no matter their level. I strongly encourage all of you to attend if you are within driving distance.

Hope to see you there,

P.S. You do NOT need to be a member of the PTG to attend!

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