Squeaking Keys

Quick Answer: Your solution might be a simple drop of Protek away (you could also use denatured alcohol).

Quirk Answer: You might have acquired a new resident.  Charge him rent!

Long Answer: While there are several issues that can cause your keys to squeak I will be focusing on one that I came across recently.  The squeak is usually so slight that under normal playing conditions you would not hear it, however this particular squeak is a symptom of a repair that your piano will eventually need.

Subtle enough?  Did you notice that when the key was shifted a bit to the left that when played the squeak disappeared?  Did you also notice the depression in the red felt to the left of the balance rail pin?  Did you also see then angle of the key?  All of these observances will tell the discerning technician what is wrong and how to fix it, however there may also be a simple solution that costs pennies compared to hundreds of dollars.

If you re-watch the video you will notice the note not being played has an area around the felt that appears to be wet.  There are a couple of reasons a key will make this sound:

• Hard Felt
• Significant amount of dust

While I cannot prove that significant amounts of dust cause this it does stand to reason that dust or debris between the balance rail key pin and felt could cause this noise.  I usually will attribute the noise to the hardness of the felt.

What makes the felt hard? It often is the case that the manufacturer applied too much glue which then wicked all the way through the felt, this glue has historically be hot hide(animal) glue. Modern pianos use another type of glue or adhesive and I find that some of these glues wick through the felt more than others. Hide glue while not necessarily ideal when used in its "hot" variety doesn't wick as much since it begins to cool as soon as applied to the felt and will be set in a much shorter period of time and many other glues.

In pianos, when two hard surfaces are in contact with no "soft" buffer material you often will get a noise.

Back to our squeak...

The angle of the key can prematurely cause wear on the felt bushing creating more grooving on one side of the key.  This will wear away the felt faster as they key slides back and forth across the felt. This wearing away of the felt will reveal the undersurfaces to where the glue has penetrated. Typically keys whose angles behind the balance rail key pin are to the right (treble) the felt will wear on the left side. Keys with angles to the left (bass) will wear on the right side.  This angle creates more pressure on the opposite side.

Improper "key easing" can cause this uneven wearing also.

The proper repair is to replace the felt ensuring minimal side to side motion allowing the key freedom of movement with minimal friction.

A quick and effective treatment is what I will describe below the video which shows the same key as the first video but without the squeak.

Using my trusty favorite non-destructive lubricant (Protek) I apply a drop or two to the felt. Viola, squeak resolved.  This lubricant is not generally available to the public.  You can try a drop or two of denatured alcohol which would hydrate and soften the felt but leave behind no lubricant.  Be warned I use a hypo-oiler with a very narrow needle.  If your felt was glued on with hide glue, too much liquid in any form could dissolve the bond between the felt and key forcing you to have the "proper" repair done.  Some woodworking shops will carry a fine point glue applicator that will allow you to apply a drop of this liquid onto the key bushing felt.  The drop you apply should be less than 0.03 ml which is the standard medicine dropper drop size, you must have a drop smaller than this.  See the picture below to see the difference between a regular medicine dropper and my hypo-oiler bottles.  I use the small bore needle and bottle with my lubricant.  These particular bottles are from Gaunt Ind. "Hypo-25" (3oz. Small bore) and "Hypo-494" (6oz. Large bore) and available through some piano technician parts suppliers.  Prefect for applying just the right amount of lubricant.  Without a dropper, it might be possible to brush a thin amount rather than trying to apply a drop on the felt.  Should you choose to attempt this with an inexpensive artist brush, be sure to vacuum the tops of the keys and felt to prevent further possible contamination of the felt.

Dropper (Left), Large Bore (Top), Small Bore (Bottom)

As with all my technical tips, use caution when applying the "fix"

I always inform my client that if this treatment does not resolve the problem they will need to have the key bushing felt replaced which can be done in about three days (day one - felt removal, day two - new felt, day three - customize fit to the piano). Day three is minimal if I have done the glueing and pre-sizing properly. The actual time it take to perform this is 8 - 16 hours.

Hopefully you can delay the inevitable felt replacement for another few years or until a more financially appropriate time.

To translate my quirk answer... what little house pest squeaks? A Mouse, and mice love piano houses... there is so much to chew and destroy.  Trust me, if you have mice in your piano, it's best to get them out as quickly as possible, they cause significant damage that could ruin your piano.  The next time I come across one I will post my process of cleaning after they have been removed from the instrument.