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Monthly Technical

We often take for granted those little white and black keys. They set our melodic passages to motion within the piano as our fingers skillfully glide across them. Truly, if they have a good feel they are as well-fit leather gloves to our hands. If they have broken or sharp edges and sideward movement, it is unpleasant and lend inconsistency to our musical experience.
We will begin the discussion with several aspects to these keys that give us the good or not-so-good feel to our instrument. The keys are generally made of a high quality light weight wood that has a centerpin pivot point and a frontpin under the approximate placement of our touch point that maintains consistent alignment. The two keypins (center and front) glide though their key mortises with high-density wool felt carefully lined inside the keys to give them a minimum of side movement and a smooth feel.
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At the opposite side of the key's playing surface you will find the capstan. (On the grand keys it also includes the back-check which catches the hammer just after it strikes the string). In the picture above you will notice that the brass capstans are polished with brass cleaner and then lubricated to reduce any friction from metal oxidation. Likewise, in the lower picture, notice the keypins as well are also cleaned and lubricated. This is part of the maintenance program I call "friction point service". This greatly enhances the ability to have a very responsive key and that aides in the dynamic expression and repetition speed of our piano!
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Following issues, we will see the process to "rebush" the keymortises and restore the new feel from worn key-bushing felt that give us a loose/sloppy key movement. Today, let us examine the keytop surfaces and what can be done in restoration to the feel and appearance of them. Of course, our present and end piano value must be considered before entering into this investment. This may increase a quality piano value, but may exceed the reasonable investment value of low-end pianos. There is always someone to take your money! The keys below were just requiring a few ivory replacements. The ivory must be matched for color, thickness, length, and width. This is not just a process of taking old ivory off one used key and placing on another!
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The above ivory and ebony keys have been "restored" with color matches and then polished. This is a premium to actually have the "Good Stuff." This comes at a high price, and plastic replacements may be more economical if there were several to replace. Below is a plastic keytop replacement that simulates the ivory color in an alternative to "bright plastic white." This is my preference for older pianos to enhance original appearance when the original keytops are not an option.
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An alternative to a low value piano maybe to simply file off the rough end edges, (see below). This allows you to still have the ivory feel and significantly reduce the cost of a complete keytop replacement.
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The next picture shows the process of new keytop replacements. This is a very exacting process to maintain key squareness, consistent key thickness, and proper adhesion and finished edges.
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Notice the new red Keybushings (center) have also been replaced. Many times, piano keytops have been replaced without replacing the worn keybushings. I believe that is like repainting a nice car without repairing the body underneath the new paint. The end result is not only to "look good", but most important, it is the TOTAL FEEL that a finished job results in!
After the keys have the keytop surface restored or replaced...the keydip and the keys need to be leveled. This includes white and black keys.
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Hopefully, this topic on keys may help you appreciate the significance of how they not only look but especially the feel of them. Several of you have emailed with questions on specific considerations on your pianos. We are always glad to hear from you. We may not be able to service your piano in a distant location to us, but we always enjoy helping you through those important decisions to your piano.

There are many skilled piano technicians all over this wide world! I hope that in the next few months these technicians may help you appreciate their devotion and love to the art of restoration of the quality instruments. A first-class restoration adds value and years of pleasure to your musical experience.

Key Issues

In the previous issue you might have noticed that occasionally the keys are in good condition and yet the key bushings are being replaced. The quality and tolerances of some piano manufacturers becomes evident after a few years of use. Sometimes the piano may have many things in good condition, and yet, the quality of felt used in the keybushings becomes obvious.
When the time comes to rebush the keys, the cost of the highest-quality bushing felt compared to moderate bushing felt is a small price difference compared to the labor and the skill of your technician. I do not want to promote a certain brand of piano over another, but I have rebuilt high-end pianos that have over 60 years of service where the keybushings were in better condition than lesser-quality pianos with less than 10 years of use. Some of the prices reflect long-term cost in maintenance, tuning stability, and resale values. I would highly recommend reading "The Piano Book," written by Larry Fine, where he addresses these grades of pianos.
the piano book
After the key bushings, the key surfaces (keytops) and the center pin holes are restored to good condition, the next attention concerning the actual keys must be toward the keypins, capstans, and the keyframe that the keys rock upon. If mice have roamed wildly in this piano, their urine has probably ruined the centerpins.
Polishing or sometimes complete replacement must be considered. This relationship of key fit and making a frictionless movement has everything to do with the success of speed of repetition and level of dynamic control or the lack thereof. Without a good fit of keys and keyframe, it is impossible to refine the "regulation." (Regulation is the relationship by timing of the mechanics within the piano action that transfers fine touch movement into musical tone and expression.)
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The condition of all felts, including: #1, the back cloth, #2, the center pin punchings, and #3, front pin punchings, is very important to give a firm, consistent and level feel in the keys. Friction-free fit has everything to do with clean and good-conditioned parts and not to be substituted with simply using "lubricants," as lubricating poor or dirty parts will always give poor long-lasting results.
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The condition of keys' capstan requires a perfect symmetrical and polished friction-free surface to continue the effort of a perfectly functioning piano. Sometimes the capstans' surface tops are less than perfect, having burrs and machining ridges that can be improved with a good polishing.
Attention as well to the fitting of the keyframe to the piano's keybed is the very "foundation" of the total rocking up and down as it puts the action into motion.
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The keys require a precise dip amount that is a 1:5 ratio of keydip to amount of hammer travel from the rest position to string contact. If this relationship is not correct, the end result is very noticeable in speed, power, and touch to the instrumentalist.
One issue about the keys we will not discuss presently but may be good for you to know for further discussions is the weight or lead in the keys. Sometime in the future we will discuss touch weight and hammers and their relationship. Below is a picture to display what they look like.
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This concludes our series of "KEY ISSUES." I hope it has given you some new appreciation of these little white and black keys that, if in correct order, make our efforts a pleasant musical experience!
I always look forward to your email and correspondence regarding these articles. ​
Several of you have contacted us concerning the possibilities of new keytop replacements on your instrument. My reply to your consideration of this in your piano was:

"What is the current value and condition of your piano, and what will the end value of your piano be after this considerable investment is completed?"
There are many who will take your money with no consideration to, "was this a wise investment of your dollar?" Yes, there are many worthy instruments that this will greatly improve the pianos end value but equally, there are also more instruments that could use this service but the cost may be more than the actual value of the "fair market value" of that instrument.
The piano picture above would fit in the group that key repairs if significant may not justify the investment (in my opinion). The waterfall keys are very interesting but are outrageously expensive to repair/replace. These types of keys were almost entirely in spinets and consoles that the present age now have other aging areas that are requiring attention. I don't know of any moderate- or high-value pianos with this-style keys that would justify the cost of new keytops of this style. Perhaps by making that statement, if there are some, I will hear from someone and I shall stand corrected and report this to you! Until then, I will keep this statement.
You may have noticed in the pictures that by the time I am replacing the finished keytops, the keybushings have been replaced. This is for good reason. The keybushings, if found to need replacing, will be steamed out, and the mortises and balance hole resized with steaming as well. With all this attention and steaming process, the risk of damaging any keytop surface must be given consideration to saving it for last. Many times it may have been the keytop was the first reason to begin this process.
Let us first examine the condition of the keybushings to evaluate the need.
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The above center keybushings are not only very worn and loose, but the glue has loosened to where the felt is actually missing from some bushings. (See the middle one.)
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The next picture you may notice there may be broken keybuttons to repair as well.
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These front keybushings have many damaged from moths and/or silverfish. There are many times that a set of keytops were replaced and yet, for some reason unknown to me, the replacement to the worn/damaged bushings had not been done.
Key Brushing Removal
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At the same process time, we will resize the balance holes by steaming these as well.​

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Immediately while the wood is still damp, the sizing cauls are inserted into the mortises or pin holes. The keys are then allowed to slowly air dry for several days before proceeding. Below are the mortises after the sizing cauls are removed.
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Next we must determine the correct bushing cloth so that the bushing is going to give a firm fit to the keypin with a minimum of side play. The original bushing cloth may have not provided a long service life if the manufacturer of the piano had used a lesser quality of bushing cloth. This is an especially noticeable difference with the lesser-priced pianos.
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The process for rebushing both front and center bushings is the same, only using the proper-sized cauls for the pin for that mortise. The glue of preference for this, as with any future replaceable joints, would be to cook/make your own fresh hide glue. The advantage of using hot hide glue is that it begins to bond as it cools, and more importantly, the glue can be steamed apart again in the future without damage to fragile wooden parts. Hide glue has been the preferred glue for many centuries in fine wooden musical instruments as well as fine furniture.
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The above vertical piano keys have been rebushed and are now ready for fitting to the keyframe for pin sizing and leveling. The bushings will require adjustment for exact fitting.
When the keys are to be rebushed I feel that it would be better to err with an extreme high-density wool bushing cloth and endure a "break-in period' just as with a new piano. The end result will be a longer durable bushing of much greater quality than that of some manufacturers original bushings. It never fails, no matter how much I explain this, I always have to remind the pianist of it a few months after the rebushing process. The piano factories have a machine that works the keys and action felts thousands of times before setting final regulation in the piano. I don't have such a machine but strongly believe it is better to have tighter tolerances to start with than to fit with looser fittings that after a few years are not any better fittings than the worn parts we replaced in the first place!
I will carefully "iron" these new bushings to settle them, as well as polish the pins and treat the bushing cloth with Teflon. This does not mean that we are not going to have to still play-in the fit! The wonderful end will be a nice solid feel with no side play.​
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Just like ironing anything...the temperature must not be too hot! 
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There is another process of just "easing the keys" which is basically crushing in small increments the side walls of the keys on each side of the new felt bushings. To some piano techs this is a fast fix to sluggish tight-fitting bushings. I personally believe if the keymortises have been correctly sized and the felt is fit properly with high density felt, there will be no longerlasting solid substitute than to avoid the temptation to "crush" the keys but instead patiently iron and break in the fit. 
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Above are a few key tools used in this process: (1) Key-easing pliers, (2) Pin bender, and (3) Pin hole easer tool (for the center key-balance hole as well as bushings). The first tool, as you know, I'm not very fond of as I have explained. It is because of the use of this tool that I steam the mortises back to dimension and repair the previous damage of key compression prior to rebushing with new cloth. (But then, that is in my humble opinion.)
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Arbeau Piano

PO Box 1053
Blue Springs, MO 64013
Phone: (816) 228-8805
Email: arbeaupiano@comcast.net

Gerald Arbeau, Piano Tech./Rebuilder/Tech. Instr.
Terri Arbeau, Piano Instr./Educato
Hours:
Monday-Friday
By Appointment Only