It’s inevitable that chips will happen and pianos will become damaged. In my estimation, the majority of accidents happen because of sloppy piano moving practices. Regardless of the cause, however, the repair needs to be done. Contrary to surface scratch repair that we learned about last month, chips have a different process. As we learned, “if you can feel it, you’ll see it”, meaning that if you run your finger over the damaged part and can feel an indent of a scratch or chip, you’ll first need to fill up the void first before attempting to make it smooth again. A perfect mirror finish has light that is uniformly reflecting. When damage happens, it interrupts the uniformity of the reflection.
While most pianos today are sprayed with polyurethane finishes, they are difficult to manipulate in a home as they have substantial off-gassing (being acetone based), slow dry time and are best applied via spraying. The fix that I have found to work best is not polyurethane but rather, cyanoacrylate glue, aka crazy glue. One vital element that is a huge asset to touch up repairs is a spray accelerator. The repair can be done without the accelerator but you need a lot more patience to get the job done as you need to often apply multiple coats and wait for drying time of several minutes in between coats. The accelerator dries the glue in literally 3 seconds. As you will see, cyanoacrylate glue (CA glue) has 2 challenges – one is color and the other is hardness. While the color is almost the same, in certain lights there is a colour difference to many piano blacks. The second is hardness. The glue will not be the same hardness as the age-old finish of the piano and should be treated with a bit more awareness when sanding.

Let’s get started.

Surface Preparation
One thing that is of utmost importance is finding out the adhesion of the chip. Sometimes the chip doesn’t look big but if you tap all the way around it, you can hear the difference between an area that’s solidly attached to the substrate and a very high-pitched sound where it has come loose. There is no value in repairing something that is loose. So, either you need to chip away the loose part and, in essence make the damaged area bigger to where the veneer is firm or you need to insert glue under the loose area and make sure it bonds to the underlying wood.
A very important step in the surface preparation is the edge of the chip. I’ve learned that you can do an impeccable repair but if the edge of the chip is not sanded, you’ll see a white line surrounding the entire fill that you just finished. Take the time to sand the edge of the chip all the way around with very fine paper – somewhere between 800-1200 grit. Basically, you want to smooth any rough edges so that the light does not reflect the edge of the chip. Sand on a 45 degree angle facing into the body of the void.

Filling
It should be noted that there are 2 common mistakes people make when trying to repair a chip in a piano. The first is that painting the crater with something shiny will fix the visual appearance. This will result in a shiny uneven surface that looks like nothing more than a shiny bumpy finish. The void must be filled. The second mistake is that adding material (as in CA glue) will be fine if you just glob it on. The reflection will not be uniform with the surrounding area and look like a blob. It must be first levelled and then sanded and completed with polishing.
With CA glue in hand (using proper gloves… remember it’s crazy glue!), dab small amounts of glue followed by a spritz of the accelerator. Do the same thing over and over until there is an abundance of material. You don’t want to simply make it the same height but make it feel like a “speed bump” so that when you run your fingers over it, you’ll certainly feel it. Once the area is sufficiently filled, you can move on to the next step of levelling.

Levelling
The goal here is to approximate the height of the finish to the surrounding area. For safety, I often put down some tape in the surrounding area so that I don’t inadvertently scratch a perfectly good area. The two tools I use for levelling are a file and a modified razor blade. With the file set parallel to the finish, you can take off really high places. I probably do more work though with a dull razor blade that has been modified with 2 pieces of scotch tape on the sides. The tape raises the scraping surface by a fraction of an inch and also (and probably more important) covers the corners which are wickedly sharp and will make a scratch in your finish without blinking. Working perpendicular to the scratch, scrape off the finish until it is grayed and level. The finish shouldn’t have any bubble holes or marks in it. If it contains these, the end result will be less than satisfactory and I would recommend going back to filling and then re-level the area.
Rough Sanding
Remember this: lower number sandpaper offers the advantage of removing material quickly but requires endless amounts of time to remove those sandpaper scratches in the finishing stages so use the highest number paper to create a level surface. For this job I chose 400 grit paper.
Fine Sanding and Polish
Remember last month’s article on removing scuffs and light scratches? The process is exactly the same from here on. Using consecutive numbers of higher grit paper, work through the papers sanding at 90 degrees. Each grit exchange, change on a 45 degree pattern so you can see the sanding lines change. Once you reach 3000-4000 in Micro-Mesh, do a circular pattern and move on to buffing and polishing. The end result can be quite satisfying.

Disclaimer: while this presents one solution to repairs, this is by no means exhaustive. It is just one method that I have found to be successful over years of working with pianos. If you don’t have the right equipment or feel unsure about tackling a finish, you might be better off not doing the work and talking to a professional. We are not responsible for your piano and the subsequent results. This is simply a demonstration that shows how to get successful results.

Materials used
Black CA glue
Activator
800 grit sandpaper
Micro-mesh sanding cloths
Razor blade
Polishing wheel and buffing pad
Cut compound
Buffing compound
Chamois

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