How to fix sticky piano keys DIY: Common Quick Fixes & Causes

Kevin Busse Feb 20, 2024
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Sticky piano Key

Here’s an overview of the DIY fix, typical causes, and professional piano technician applied remedies.

How to quickly fix a sticky key?

The best way to deal with the sticky keys problem on your own is to wiggle it side to side in 3 different ways:

  • Wiggle while at rest

  • Wiggle while in the down position of the key stroke

  • Wiggle the key upward above its rest position

If there’s a sticking key on a piano, it’s good news that in most cases this easy fix is possible for you to do all on your own.

Whether it’s coming from a black key or a white key, try this method before calling a technician.

When should I call a Piano Tuner to fix a sticky key?

  1. If the remedy listed above doesn’t work!

  2. When a foreign object gets stuck in the front of the key (paperclip/penny/guitar pick) or at the back end of the key behind the fallboard (a pencil).

  3. When adjacent keys are affected, it’s better for a professional Piano Tuner to find the root cause than to brute force this solution in an attempt to resolve the issue.

  4. The lowest or highest note is rubbing against the cheek block.

  5. The key slip (wooden panel in front of the keys) rubs and holds the key in the down position.

  6. The fallboard is clicking against the back of the sharp keys.

What causes sticky keys?

  • Relative Humidity Changes

  • Foreign objects

  • Key slip

  • Cheek block

  • Fall board

  • Lack of preventative maintenance

  • Age

Relative Humidity

Fluctuating Humidity levels is the most common cause of sticking piano keys, believe it or not!

Unwanted friction causes sticky keys, as a direct result of humidity changes. Humidity changes are always a valid culprit for sticky keys. Slight wood swelling and contraction due to humidity causes 3 main common problems:

  1. The front key bushings, which are located at the underside of the front end of the key, have too much friction against the front rail pin. The front rail pin guides the key as it is pressed downwards.

  2. The balance hole, which is located at the fulcrum of the key, rubs with too much friction around the center pin. This hole plays the largest role of holding the key in place.

  3. Keys rubbing against its neighbor. With extreme changes in humidity, the keys may warp and rub against one another.

Foreign Objects

Sometimes, an unwanted object gets stuck in the action of the instrument and interrupts the normal function of the keys. This may be due to a pencil, guitar pick, and even an iPhone!

An obstructing object to the keys path is a much more obvious problem. You can tell if there is a foreign object in a few ways:

  • The key doesn’t have full range of motion

  • Odd “clicking” noise

  • Severe increase of friction

Key Slip

The movement of the keys can be affected by the key slip, which is the piece of wood directly in front of the white keys.

This could either be a result of humidity changes or regulation adjustments made by the piano tuner/technician.

Cheek Block

If the lowest key or highest key is the stuck key, the cause is likely friction against the cheek block.

Using the shift pedal may temporarily address this problem, or an adjustment to the positioning of the key frame in the key bed.

Fall Board

Rarely, the back of the black key (sharp keys) rubs against the bottom front facing side of the fall board which can cause a clicking noise or cause the key to stick.

This can be remedied by the technician with adjustments inside the piano.

A Closer Look at Piano Key Friction

Pressure induced friction

This type of friction is one of the most common causes of sticky keys, which is readily attributed to humidity changes.

Wood swells and shrinks tangentially, about half as much radially (both affecting the width of the keys), but practically not at all longitudinally (key length stays the same).

With pressure induced friction, the shape of the wood fluctuates in 2 main ways. Both ways cause friction against the metal guide pins (key pins) as a result.

  1. Wood Swelling (swells outwardly, against key pins)

Typically, this movement increases friction by the front key bushing and balance pin bushing against the front rail pin and balance rail pin, which can be remedied by the technique discussed above.

  1. Wood Contraction (tightens inwardly, towards key pins)

Typically, this movement increases friction by the balance hole against the balance rail pin, which can be remedied by the technique discussed above as well.

  1. Wood may “cup,” “bow,” “twist,” and “crook.”

These types of sticky key occurrences are rare.

If the change is large enough, the keys could rub their neighbor, requiring a technician to fix.

Textural friction

While not as common as pressure friction, textural friction can cause sluggishness in keys.

  1. Bushings and textural friction

While sticky keys are primarily caused by the swelling and contraction of the wood, to a much smaller degree, the felt bushings produce a textural friction against the key pins slowing the key down.

Preventative maintenance by piano technicians with liquid lubrication, which is ubiquitous in the piano industry, will resolve this common issue.

There is an important distinction between the abundant lubrication of key bushings vs. action center bushings (which may only be lubricated using center pin lubrication at the piano technician’s discretion).

  1. Dirty rail pins contribute to textural friction

On older pianos, the key pins may become tarnished.

Polishing key pins is a common practice due to the reality of the key pins becoming tarnished.

This tarnish requires removal of the cabinet parts and piano action to polish the key pins to restore proper function.

How does a professional Piano technician fix sticky keys?

Professional help from a piano tuner involves taking off the case parts of the piano, which is the first step in normal maintenance.

Piano tuners generally use these few tools and materials to fix sticky keys:

  • Key easing pliers

  • Balance hole reamer

  • Prolube lubrication

  • Teflon powder

With these tools, the piano technician can resolve the most common causes of sticky piano keys.

If the remedy listed at the top of this article doesn’t work after a few tries, then it’s time to call a piano technician!

Final thoughts

Sticky keys may be caused by a variety of reasons.

Piano parts of an acoustic piano are made out of wood, which are susceptible to fluctuations in humidity which is the most common reason for a sticking piano key.

Old pianos especially have their fair share of sticky keys, which more likely than not will require a skilled technician to fix.

The importance of humidity control cannot be understated for the proper functioning of all pianos.

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