How do you repair chipped ivory piano key caps? - created 05-25-2010

Brown, Travis - 05/25/2010.11:48:31

I've got an old Nordheimer upright that had tenure in an elementary school for a while. As a result, a lot of the ivory keys have been chipped. I'm more interested in restoring shape than appearance. Any acrylic or epoxy type material that is good for building up the fronts of keys? I was thinking it would be similar to how nail technicians work on fingernails.

Old, chipped key tops are usually just replaced, or filed off for a "waterfall" front. Perhaps contemporary piano technicians are doing fingernail-like repairs, but I don't know about it if they are.

The "ideal" repair is to find some old ivory tops off of another piano and repair the missing or damaged.

I suspect too many are missing and it will not be easy to locate replacements.

The next best is to take all of them out, and trim off the top a few thousands on the table saw, and then glue on the plastic key tops. You will need to file the edges even afterward.

The lip on the tip of a piano key is important. The feel of the piano is not right without it.

Ivory keys have a specific feel when played as compared to plastic. Manufacturers have attempted to create a plastic that feels the same. They have not achieved this yet.

If you google for "piano repair parts" you will find several companies that provide the materials.

By chance, I just actually replaced all the keytops on my wife's family's old upright. It is about 100 years old. The keytops were original. Many were chipped. Many that weren't chipped were still very worn.

If you go shopping for ivory keytops at a place like ebay, keep in mind that sellers there are (or were) not allowed to use the word "ivory" in their listings. When I sold my old keytops (sorry, I would've loved to have been able to help you out), I listed them as "100 year old piano keytops."

I started out wondering if I could replace or fix some, much like you are, but I quickly realized that, in my case, I was not going to be able to get an even appearance and feel across the entire keyboard.

I bought a set of simulated ivory piano keytops (plastic) for about $25, and I am very happy with them. They look pretty great, and the family (I don't play) is enjoying the instrument much more now, than they ever did when it had old ivory keys on it. The feel is even, and the look is very clean. Incidentally, I sold the old keys for much more than $25.

If you go this route, after gluing the keytops on, you may have to shape the keytop to fit a couple of keys. A few of keytops were a little wider than the keys themselves, in places.

The piano technician that I know uses a home construction adhesive in a big tube to glue the keytops. I borrowed it, and, heck, I don't know what brand it was. It was in one of those caulk guns, and the adhesive itself looked kind of like gummy silicone. You will definitely want something that has the ability to shrink and expand with the wood, otherwise, some of your keytops will likely pop off within a year. I squirted some of it on a paper plate and used a popsicle stick to spread it on the keys and the undersides of the keytops.

You don't have to buy specialty cement, you can get what you need at a hardware store. If you're interested I can find out what it was.

Good luck, Travis. I didn't answer your question, but I just wanted to share the outcome of my own recent similar experience.

I had a container of key top cement when I rebuilt my player piano many (ahem) years ago. It was white, and unless the same white adhesive was used under all the ivories they didn't look the same color. Perhaps with plastic key tops the adhesive doesn't matter so much for color, and perhaps when replacing all key tops it doesn't so much matter, but if you are replacing part of them they may not look like the others if the adhesive is not white.

The original ivory keys were glued on with a little strip of white adhesive. I don't know that it is at all available. I have not seen it in any repair catalogs.

The ivory adhesive I had (quite a while ago) was a white xylene or toluene type of material.

For the plastic keytops, the white material is not needed, as the keytops are opaque and quite thick.

Thanks for all the suggestions, esp. about the adhesive. I'd probably have just used contact cement.

I'll try chipfilling with some with some kind of mastic first, just to see what happens. There are a couple keys that would be better off replaced, but I'll just watch for some old discarded pianos that one comes across from time to time. I'm sure it wouldn't be too long before I managed to acquire enough for a complete replacement.

Hey, finally a question that I can answer authoritatively! I'm a piano technician, a Registered Piano Technician member of the Piano Technicians Guild, and I have extensive experience in repairing keytops and restoring old pianos.

The adhesive used for ivory keytops is hot hide glue mixed with TiO2 as an opaque whitener. Usually a layer of muslin fabric, saturated with the glue, is layered between the keystick and the ivory, to help absorb the different rates of expansion due to humidity change. Hide glue impregnated "wafers" can be purchased from piano supply houses such as http://www.schaffpiano.com/catalog/piano_key_material_and_recovering.pdf

To use the wafer, place it in cool water for 30 seconds, assemble the wafer and keytop to the keystick, then clamp with a 1/4" thick metal caul heated to around 150F.

I've seen many other adhesives used to re-glue ivory that didn't hold up, including contact cement and Duco.

There is a quicky field repair method that has only been in use for a few years, but seems quite durable and reliable: apply a thin layer of white glue to the keystic; apply 2 or 3 drops of thin CA to the ivory and spread it evenly over the entire surface; place the ivory keytop on the keystick precisely where you want it because you get no time to adjust it.

Some of the earlier plastic key covering materials were adhered by brushing a solvent onto the keytop to make it soft and sticky. These are the keytops that appear wrinkled or wavy.

Modern plastic keytops were traditionally attached with contact cement, but there is growing us of PVCE glue. It's white, but it's not like a white wood glue - it dries somewhat flexible and elastic. You can find a thicker version of it in fabric stores, called "Aleene's Original Tacky Glue". Most plastic keytops are molded oversized, so plan on trimming both edges. It's analogous to fretwork - we even grind safe edges on files to trim in the "notch".

But to your original question about repairing chips, modern technicians use a product called AcryliKey. http://www.wagner-technical.com/index.htm It's a two part mix, cures in just a few minutes, and can be filed/sanded/polished to match the surrounding ivory. Not an invisible repair, but hard to find if it's done right. Highly toxic, respirator and gloves recommended.

You can find more discussion of this topic, and many others, at the pianotech list, http://ptg.org/mailman/listinfo/pianotech

Hope this helps, and good luck with your piano project.

Thanks for the clarification Mike.