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Nitro-Cellulose is reduced at a ratio of 1 to 1 with reducer if you are spraying it. Make sure you use the right type and you cannot use reducer for acrylic enamel which is a common error.

Find Mohawk paints website and take a look at the catalog. They are based in North Carolina. They carry a wide variety of piano related finishing products.

I'm refinishing my nitrocellulose piano.
The old finish is crazed.

Just want to verify a detail.

I'm taking real time to sand it, wherever it is actually loose and flaking. And where a flake has come loose, I'll sand the whole area to make sure I don't have a low spot.

But that is ALL I must do, correct?

Where the finish is intact, but crackled, I can respray over it, and the new nitrocellulose will melt into the old?
smoothing it out, restrengthening the old finish, covering over the crackles, restoring some gloss?


I'm more familiar with shellac, but a buddy is teaching me to spray nitro. First time working with it, and first time repairing an old nitro finish. Just wanted to double check this point.

If I don't have to sand the ENTIRE case, to just smooth it out with some new fresh coats-- that would be awesome.
Other areas, like the music desk, that show extreme damage-- I've sanded to bare wood and then restained to match before spraying.

An amalgamator will help flatten the checking.

excuse me but what is "checking" ?

On polyurethane or polyester you may use any kind of lacquer, PU thinner can thin/cut NItro lacquer, also.

polyester will make a white scratch (and can be cracked)

I actually found Mohawk products by accident when I joined professional refinishers group. I can understand not reducing the gloss lacquer because you will lose sheen without adding hardener but I use two products of theirs mainly but I am curious about their gloss black and may try that out too.

The high build clear piano lacquer is awesome. The type of grain filling I do is old school and will wear a person out. It requires rubbing the surface of the wood with a filler caked burlap bag, after brushing, squee-gee- ing ( sherwin williams oil based Sherwood) until it is basically glass smooth and sometimes there will be a tiny spot missed. The clear Mohawk stuff takes care of that within 2 coats.

As far as the black goes I use the Satin Black colored Lacquer. I will get you a part number if you can't find it. It's reduced 1-1 and the air supply needs to be cool which is one of the secrets of using nitro-cellulose. If you don't have air you can get a tank of dry nitrogen and regulate that. Electric HVLP equipment will not work as the air coming from the hose is too hot unless you can run it through some bags of ice.

I bought 4 gallons of Mohawk products and then they called me to get me dealers rates which will save you like 12 dollars a gallon. They do sell 5 gallon cans but the hazmat shipping charge makes it cheaper to buy 1 gallon cans.

I'm refinishing my nitrocellulose piano.

Where the finish is intact, but crackled, I can respray over it, and the new nitrocellulose will melt into the old?
smoothing it out, restrengthening the old finish, covering over the crackles, restoring some gloss?

Hello again Mr. Oleg,

And, how do you repair such white scratch?

May I use this forum as a confessional?

When I was much younger, I enjoyed opening the lid of my aunt's brand new Schimmel grand piano to play it in all its grandeur (beautiful walnut, chestnut, or cherry, I don't know). This is European piano with the polyester finish, as you know. She used to keep a ceramic-base table lamp on a cloth on the piano top. So in removing the lamp to open the lid, one day, I put a terrible gouge. Yes, I can attest that there is a white scratch that results. Some polish on hand dulled the white, but obviously did't go far to fix it. I never had the courage to tell her, I put the cloth and the lamp back. Some years later I got married and I told my wife the story of the scratch. Then, my wife met my aunt and discussed the story as if my aunt already knew that I had done this damage (but at the time she didn't). Many years had passed however.

So how do you repair such white scratch?
(I am also curious if this is a professional service you provide?)

From this experience, and also with my parent's upright, I am of the opinion that lamps of any kind are one of the most dangerous things for the piano.

Best wishes -