Since posting a while back about repairing loose autoharp tuning pins, I have received a lot of inquiries (well, seven) about the use of cyanoacrylate glue (CA) as a pin tightener, particularly in pianos. Most of the questions have concerned what type of product to use, how to apply it, and, can it be a Do-It-Yourself repair. Only one person reportedly planned to employ a piano technician and no one indicated any safety concerns. I can totally relate to a DIY approach but before I address the subject, I offer this advice/disclaimer:
Don’t do this yourself. CA is “nasty-in-a-bottle” and you will use two of them. It reacts instantly to dermis, the vapor it produces can cause respiratory problems, and you risk sticking things together that might be better off moving around.
Hire a piano technician for this job. He/she has experience with this, can make informed decisions for your piano, and will be the person tuning it for years to come.
That being said, the following is for recreational reading only!
A piano contains over two hundred finely threaded tuning pins driven into the slightly undersized holes of the wooden pin block. To tune each string to its precise desired pitch, its pin is turned righty-tighty or lefty-loosey leaving friction alone to hold it in place. Over time, tuning pins lose their ability to hold for a variety of reasons. Turning the pins eventually causes excessive wear. Very dry conditions can cause the wood to shrink from the pins. Cracks can develop or the block can de-laminate. Pins can become loose to the point that the piano won’t hold its tune between ever more frequent tunings or even until the piano tuner can race to the bank to cash your check.
All of the pins don’t fail at once. Sometimes there are only a couple to a few bad boys that just cannot be tolerated. They can often be remedied by driving them deeper into the block, shimming, or replacement with an oversize pin. The cost can easily be calculated by multiplying the (number of pins) X (expensive). It’s certainly worth it though considering how much you love the instrument, the trouble and expense of acquiring it, and the cost of a replacement.
When many pins fail, it’s time to “bite the bullet” and have the piano rebuilt. In a few months a professional restorer will install a new pinblock, pins, strings, and repair all of the other piano problems returning it in better-than-new condition. This costs many thousands of dollars and again, is well worth it, but only if it is a higher quality piano or has great sentimental value.
Many pianos are simply not worth the cost of rebuilding. Even when they are, it may take some time to engage a restoration service and sell a kidney or two to pay them. Treating the loose pins, when appropriate, may add a few years to the life of a lower quality, aged piano, or buy some time while preparing for a rebuild or replacement. It can do little harm to an instrument destined for the landfill or a quality instrument that will be getting a new pinblock. It can be like a temporary midnight reprieve from the Governor. So, ask your piano tuner if CA is right for you.
In years past, piano tuners have treated loose pins with commercial products or made their own “secret sauce”, usually a 50/50 mix of glycerin and alcohol. Applied with a dropper, the alcohol would carry the glycerin into the pores of the wood and evaporate leaving the hygroscopic glycerin to draw moisture from the atmosphere, swelling the wood. All said, it works, but it takes some time ( sometimes a week or two) and it may need to be reapplied to positions where it didn’t penetrate adequately. Since glycerin relies on atmospheric moisture, it can be ineffective in dry climates or corrode the pins and string windings in damp ones.
Liquid cyanoacrylate wicks into the wood pores surrounding the pins and reacts instantly to the moisture that is already there. It gets very hot and sometimes expels smoke and vapor as it fills, expands, and hardens the wood. Excess and spills remaining on the surface set to a hard, sometimes chalky residue, but will not cause corrosion.
CA glue, aka super glue, is sold in small plastic bottles and tubes, usually with some kind pointy applicator tip. You can find it in many hardware, discount, “big box” stores and online. It comes in liquid and gel forms offering choices as to setting time and gap filling properties. For pin treatment, buy the clear liquid form that is thin like water. Even better is the type described as “ultra thin”. You can usually see through the bottle as you tip it from side to side to make certain that it is the right kind. There are several brands available but I often choose the .35 FL OZ bottles of Locktite Liquid. It comes in a pointy bottle that makes it easier to apply. To treat an entire piano usually takes two or three of these small bottles.
Before you open the first bottle you must prepare the piano. There will be less mess if you brush and vacuum away all the dust, cat hair, LEGGO toys, and other rubbish that has collected around the tuning pins. If the piano is an upright model, you must buy pizza and beer for all of the friends that will be helping you move the piano away from the wall to lay it on its back. Fail to do this and they won’t stick around to help you set it upright again. With the piano on its back, the drops of CA will flow in and around the base of the pins instead of running down the front of the frame.
A grand piano is already horizontal so you won’t have to coerce anyone to help you tip it. You do however need to remove the “action” and set it aside while you apply the CA. The grand action is the entire assembly of keys, whippens, hammers, dampers, and such that lives under the pin block that you are going to treat. Runny CA can find its way through cracks and holes to drip below, turning action parts into in-action parts and causing expensive damage. Even by removing the action to a safe place, you risk breaking delicate components so it’s a good idea to engage a piano tech for the task.
If possible, have nearby doors and windows open and a fan running to decrease your exposure to the smoke and vapor produced by the CA. It will irritate your eyes and lungs and could possibly cause long term damage. ER personnel everywhere share funny stories of their patients gluing parts of their bodies to their projects. It’s unlikely that a piano will fit in the ambulance so if you are klutzy, have some acetone or CA solvent on hand.
There you have it! A thousand words or so describing the necessary preparations, the danger, and the subtle suggestions that you call the piano technician. If you still want to do it yourself, proceed by carefully applying a couple of drops of CA at the base of each pin where it enters the pinblock. It should soak in quickly but if not, at least by the time you make a second pass. Some pianos have wooden tuning pin bushings that fill the space between the pin and the frame plate. The bushings can absorb or block some of the CA so take care to apply the CA directly against the base of the pin.
The CA sets instantly and seals the wood against future treatment but make a second pass to make sure you have treated every pin throughly. You can re-install the grand action or stand the upright upright and now your instrument is ready to tune. Call your piano tuner and confess to what you did. Arrange a tuning, breathe easy, and cross your fingers in hope that all of this trouble has been worth it… also hope that you can un-cross them .