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#2117344 - 07/14/13 02:42 AM refinishing nitrocellulose
berninicaco3 Offline
Full Member

Registered: 06/14/13
Posts: 103
Loc: iowa city, ia
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.


Edited by berninicaco3 (07/14/13 02:43 AM)

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#2117359 - 07/14/13 03:51 AM Re: refinishing nitrocellulose [Re: berninicaco3]
Jim Dunleavy Offline
Full Member

Registered: 02/27/05
Posts: 229
Loc: The Original Washington (UK)
The most critical thing you need to do is make sure all traces of wax furniture polish have been removed.

No other finish will stick over wax polish.

Here's a link to an article on how to remove polish - link .
_________________________
Jim (amateur musician and composer..and piano tinkerer).

Restoration Project Videos

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#2117371 - 07/14/13 04:57 AM Re: refinishing nitrocellulose [Re: berninicaco3]
Olek Offline
7000 Post Club Member

Registered: 03/14/08
Posts: 7904
Loc: France
Where it is cracked it may need to be stripped, in my opinion

a satin finish is easier
_________________________
It is critical that you call your Senators and Representatives and ask them to cosponsor S. 2587 and H.R. 5052. Getting your legislators to cosponsor these bills


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#2117680 - 07/14/13 08:10 PM Re: refinishing nitrocellulose [Re: berninicaco3]
Nash. Piano Rescue Offline
Full Member

Registered: 12/08/09
Posts: 386
Loc: East Nashville,TN Scottsville...
How did you establish that the old finish was Nitro-celluose? If you take a flake of finish and put it in a jar with denatured alcohol and it dissolves it is Shellac not Lacquer.

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.
_________________________
J. Christie
Nashville Piano Rescue
www.NashvillePianoRescue.com
East Nashville
Bowling Green, KY
Scottsville KY.
Chamber of Commerce
Member/Sponsor

Putting inspiration in the hands of area musicians
Through restoration/renovation

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#2117800 - 07/14/13 10:50 PM Re: refinishing nitrocellulose [Re: Nash. Piano Rescue]
phacke Online   content

Gold Supporter until November 11 2014


Registered: 10/18/12
Posts: 576
Loc: CO, USA
Originally Posted By: Nash. Piano Rescue
...

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.


M. J.Christie,

Can we suppose then you are not talking about the Mohawk 'Piano Lacquer' product, which does not particularly recommend reducing, or...?

http://www.mohawk-finishing.com/mhk_cds/product_pds/m610-130x%20piano%20lacquer.pdf

Which of their lacquer products do you like?

Best wishes -
_________________________
phacke

Steinway YM (1933)
...Working on:
J. S. Bach, Sonata No. 1 in B minor (BWV 1014) duet with violin
F. Chopin, Prelude 28 (15)

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#2117957 - 07/15/13 10:42 AM Re: refinishing nitrocellulose [Re: berninicaco3]
Olek Offline
7000 Post Club Member

Registered: 03/14/08
Posts: 7904
Loc: France
products to clean silicones are availeable.

sanding is said to be enough, but there is always a risk (craters)

cracked lacquer is stripped, then the whole finish is done again, cracks does not close when sprayed.
_________________________
It is critical that you call your Senators and Representatives and ask them to cosponsor S. 2587 and H.R. 5052. Getting your legislators to cosponsor these bills


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#2117990 - 07/15/13 12:05 PM Re: refinishing nitrocellulose [Re: berninicaco3]
Nash. Piano Rescue Offline
Full Member

Registered: 12/08/09
Posts: 386
Loc: East Nashville,TN Scottsville...
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.
_________________________
J. Christie
Nashville Piano Rescue
www.NashvillePianoRescue.com
East Nashville
Bowling Green, KY
Scottsville KY.
Chamber of Commerce
Member/Sponsor

Putting inspiration in the hands of area musicians
Through restoration/renovation

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#2118004 - 07/15/13 12:39 PM Re: refinishing nitrocellulose [Re: berninicaco3]
Olek Offline
7000 Post Club Member

Registered: 03/14/08
Posts: 7904
Loc: France
Good top to stay away of warm air or too warm room with nitro. The product needs some time to flow on the part, too hot weather gives you a not so nice orange skin defect.
The products I use are cut with thinner. If not they are not nitro but polyurethane.

I heard that new types of nitro lacquer are now used with very little volatile solvents, but they need a cooking.
_________________________
It is critical that you call your Senators and Representatives and ask them to cosponsor S. 2587 and H.R. 5052. Getting your legislators to cosponsor these bills


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#2118006 - 07/15/13 12:46 PM Re: refinishing nitrocellulose [Re: berninicaco3]
Olek Offline
7000 Post Club Member

Registered: 03/14/08
Posts: 7904
Loc: France
Originally Posted By: berninicaco3
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.


That may be all if your base coat is OK, but usually a hard base is sprayed to lock the grain, seal the wood, level, then sanded lightly, then the finish is used.

Undercoat can be polyurethane, that build up more than nitro
_________________________
It is critical that you call your Senators and Representatives and ask them to cosponsor S. 2587 and H.R. 5052. Getting your legislators to cosponsor these bills


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#2118013 - 07/15/13 12:56 PM Re: refinishing nitrocellulose [Re: berninicaco3]
Gene Nelson Offline
1000 Post Club Member

Registered: 09/10/04
Posts: 1530
Loc: Old Hangtown California
An amalgamator will help flatten the checking.
_________________________
RPT
PTG Member

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#2118058 - 07/15/13 02:32 PM Re: refinishing nitrocellulose [Re: berninicaco3]
Olek Offline
7000 Post Club Member

Registered: 03/14/08
Posts: 7904
Loc: France
"An amalgamator will help flatten the checking."

Hi Gene is it the English name ? we use a fluid called "Egalisateur" (' Evener' , if I translate literally )

On Nitro high gloss lacquer or on Nitro lacquer that can be sprayed, then rubbed as French polish.
The product is some sort of solvent plus thinner and allow the lacquer to moisten, get smoother, eventually tense when the product dries. helps with blemishes, white clouds, may allow any captured moisture to go away on a recent finish)

Indeed it may be worth a try, (with a rubber, or spraying the product, it may be sold in spray cans or in bottles) but usually when the lacquer is cracked, any work will be at the surface, then the cracks will come back soon later.

Very often also the undercoat is not NItro, but Polyurethane. I also have find polyester as undercoat, and shellac as finish (in the end not pure shellac, but a mix of shellac and cellulose, that was sprayed then rubbed by hand on the polyester coat - German pianos 60's era)

It is important to test with alcohol, acetone, nitro thinner, to understand what is (what are) the original products used.

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)


Edited by Olek (07/15/13 02:49 PM)
_________________________
It is critical that you call your Senators and Representatives and ask them to cosponsor S. 2587 and H.R. 5052. Getting your legislators to cosponsor these bills


Top
#2118061 - 07/15/13 02:48 PM Re: refinishing nitrocellulose [Re: Gene Nelson]
Olek Offline
7000 Post Club Member

Registered: 03/14/08
Posts: 7904
Loc: France
Originally Posted By: Gene Nelson
An amalgamator will help flatten the checking.


excuse me but what is "checking" ?


Edited by Olek (07/15/13 02:48 PM)
_________________________
It is critical that you call your Senators and Representatives and ask them to cosponsor S. 2587 and H.R. 5052. Getting your legislators to cosponsor these bills


Top
#2118195 - 07/15/13 08:19 PM Re: refinishing nitrocellulose [Re: berninicaco3]
Minnesota Marty Offline

Platinum Supporter until October 5 2014


Registered: 05/15/12
Posts: 7439
Loc: Rochester MN
Keep in mind that the piano is a 1936 5'6" Kimball in a mahogany finish. None of the 'Polys' would have been used with a finish from that era. Since it shows signs of checking, it would indicate a lacquer finish, as opposed to shellac or varnish. There is no suitable way to use a solvent to 'soften or re-wet' a finish from this era to erase the damage. Spot refinishing can be attempted, but they are visibly noticeable (obvious) unless done by a very experienced craftsman.

The best results are obtained by stripping the entire instrument and then refinish with the choice of any of the modern materials.
_________________________
Marty in Minnesota

It's much easier to bash a Steinway than it is to play one.

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#2118294 - 07/15/13 11:41 PM Re: refinishing nitrocellulose [Re: Olek]
phacke Online   content

Gold Supporter until November 11 2014


Registered: 10/18/12
Posts: 576
Loc: CO, USA
Originally Posted By: Olek
Originally Posted By: Gene Nelson
An amalgamator will help flatten the checking.


excuse me but what is "checking" ?


Cracking at the surface. Web search 'checking lacquer' brings up some images.

Best wishes-
_________________________
phacke

Steinway YM (1933)
...Working on:
J. S. Bach, Sonata No. 1 in B minor (BWV 1014) duet with violin
F. Chopin, Prelude 28 (15)

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#2118303 - 07/16/13 12:08 AM Re: refinishing nitrocellulose [Re: Olek]
phacke Online   content

Gold Supporter until November 11 2014


Registered: 10/18/12
Posts: 576
Loc: CO, USA
Originally Posted By: Olek


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)


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 -


Edited by phacke (07/16/13 12:09 AM)
_________________________
phacke

Steinway YM (1933)
...Working on:
J. S. Bach, Sonata No. 1 in B minor (BWV 1014) duet with violin
F. Chopin, Prelude 28 (15)

Top
#2118308 - 07/16/13 12:20 AM Re: refinishing nitrocellulose [Re: Nash. Piano Rescue]
phacke Online   content

Gold Supporter until November 11 2014


Registered: 10/18/12
Posts: 576
Loc: CO, USA
Hello Mr. JChristie,

Thank you for your comments. I have a follow-up question and a few things I can add.

>>"The high build clear piano lacquer is awesome. "
Is this a lacquer that you reduce 1:1 when you use?

>>"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"

I though the above was the New School. The old school (my impression, at least) being that you apply a coat of lacquer that pops the grain, you then sand the peaks of the swelled grains, and repeat a few times till totally smooth.

>>"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 have read that, as long as you are not running it continuously, a long hose can help. Anyway, what is the symptom in the applied lacquer if the air into the gun is too hot?

Thanks again -

Originally Posted By: Nash. Piano Rescue
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.
_________________________
phacke

Steinway YM (1933)
...Working on:
J. S. Bach, Sonata No. 1 in B minor (BWV 1014) duet with violin
F. Chopin, Prelude 28 (15)

Top
#2118314 - 07/16/13 12:39 AM Re: refinishing nitrocellulose [Re: berninicaco3]
phacke Online   content

Gold Supporter until November 11 2014


Registered: 10/18/12
Posts: 576
Loc: CO, USA
Originally Posted By: berninicaco3
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, berninicaco3 -

I feel like I have hijacked your thread. I have an amateur opinion on the matter.

To do a good job you have to do what Marty wrote, but of course you can spray new stuff on to old stuff (I see furniture fixers do this all the time) unless your new stuff has solvents that eat away at the old stuff. I think you have to test in a small area to see if the old and new materials have satisfactory compatibility if you want to go that route.

Best wishes -
_________________________
phacke

Steinway YM (1933)
...Working on:
J. S. Bach, Sonata No. 1 in B minor (BWV 1014) duet with violin
F. Chopin, Prelude 28 (15)

Top
#2118329 - 07/16/13 01:29 AM Re: refinishing nitrocellulose [Re: berninicaco3]
Gene Nelson Offline
1000 Post Club Member

Registered: 09/10/04
Posts: 1530
Loc: Old Hangtown California
Egalisateur sounds like it does about the same job as amalgamator.
Not a cure but it helps.
I use a brush to work it and help persuade the damage to semi liquefy and spread/flatten.
More finish can be added to fill.
Checking is as previously mentioned.
The finish shrinks and cracks or checks develope.

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#2118341 - 07/16/13 01:40 AM Re: refinishing nitrocellulose [Re: berninicaco3]
Gene Nelson Offline
1000 Post Club Member

Registered: 09/10/04
Posts: 1530
Loc: Old Hangtown California
Egalisateur
Interesting word - derived from egalitarian - I suppose it fits the finish better than people.
_________________________
RPT
PTG Member

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#2118363 - 07/16/13 02:08 AM Re: refinishing nitrocellulose [Re: phacke]
Olek Offline
7000 Post Club Member

Registered: 03/14/08
Posts: 7904
Loc: France
Originally Posted By: phacke
Originally Posted By: Olek


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)


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 -


Hello, yes I sometime repair, polyester damage, small ones, white cracks can be hidden with car products (black wax) or black copal, or polyester but it is very difficult, more easy to repair chips than long streaks.

Products for cars can help masking the damage in frontal viewing, it may still be apparent with lateral light or view. A good cheap solution, coral varnish (hard) is another. French polish if well applied gives a good aspect for 20 years (if applied on a crazed poly or finish) then cracks show up again.


Edited by Olek (07/16/13 06:46 AM)
_________________________
It is critical that you call your Senators and Representatives and ask them to cosponsor S. 2587 and H.R. 5052. Getting your legislators to cosponsor these bills


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#2118401 - 07/16/13 05:53 AM Re: refinishing nitrocellulose [Re: berninicaco3]
Jon Page Offline
Full Member

Registered: 03/13/09
Posts: 331
Loc: Harwich Port, Cape Cod, Massac...
You are headed for a disaster. You need to strip the old finish completely. Otherwise, it will lift or craze even more when you apply a new lacquer finish. If it doesn't, or if you use a water based finish to avoid a retraction, eventually the crazing will bleed thru after a few years. There's no quick or cheap workaround to a good finish.
_________________________
Regards,

Jon Page
Piano technician/tuner
Harwich Port, Cape Cod, Massachusetts, USA
http://www.pianocapecod.com

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#2118418 - 07/16/13 07:11 AM Re: refinishing nitrocellulose [Re: Gene Nelson]
Jean Claude Offline
Full Member

Registered: 09/18/11
Posts: 390
Loc: France
Originally Posted By: Gene Nelson
Egalisateur
Interesting word - derived from egalitarian - I suppose it fits the finish better than people.


Egalisateur is from the French ├ęgal meaning equal hence 'equaliser' (Lat. aequalis)


Edited by Jean Claude (07/16/13 07:15 AM)

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#2118474 - 07/16/13 10:18 AM Re: refinishing nitrocellulose [Re: berninicaco3]
Olek Offline
7000 Post Club Member

Registered: 03/14/08
Posts: 7904
Loc: France
Thankiou!

The product is used to work the surface, so defects or traces are leveled.

Probably it could be simply sprayed or brushed heavily, but it is better to work with it than yo leave the work to the product, seem to me.
_________________________
It is critical that you call your Senators and Representatives and ask them to cosponsor S. 2587 and H.R. 5052. Getting your legislators to cosponsor these bills


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#2119384 - 07/18/13 12:47 AM Re: refinishing nitrocellulose [Re: Olek]
Steven Bolstridge Offline
Full Member

Registered: 06/13/05
Posts: 200
Loc: Fitzgerald ,GA
It needs to be stripped and finished properly. Sanding can make the final finish uneven and blotchy. Why do all this work on a hunch or a gamble?
_________________________
piano tuner/technician

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#2119504 - 07/18/13 08:17 AM Re: refinishing nitrocellulose [Re: Steven Bolstridge]
Olek Offline
7000 Post Club Member

Registered: 03/14/08
Posts: 7904
Loc: France
Originally Posted By: Steven Bolstridge
It needs to be stripped and finished properly. Sanding can make the final finish uneven and blotchy. Why do all this work on a hunch or a gamble?


It can be done if the undercoat is not cracked or whitened, and if you spray satin or matt finish.

If stripped, the grain have to be closed which means a lot of product and coats.

Cellulose finishes once the undercoat is done can mean as much as 8 coats, as the thickness of the lacquer , for one spraying is really small. But coats can be done at 30 minutes interval, in quiet temperature (too hot and the spray dry before attaining the case)

Better use Polyurethane if the complete lacquering have to be done. this is really toxic and smell strong.

Or apply a French polish, but one need to know how to do, what to use, etc (dismount whatever is necessary).

The low pressure guns mean the spraying is done near the surface. AT last it apply 65% of the product (standard spray guns 30%, the rest goes in the air)

here the top have been fine sanded, spots of colour on water stains and 3 lacquer passes.

_________________________
It is critical that you call your Senators and Representatives and ask them to cosponsor S. 2587 and H.R. 5052. Getting your legislators to cosponsor these bills


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#2119526 - 07/18/13 09:20 AM Re: refinishing nitrocellulose [Re: berninicaco3]
Nash. Piano Rescue Offline
Full Member

Registered: 12/08/09
Posts: 386
Loc: East Nashville,TN Scottsville...
Just an added note on sanding for novices. Avoid the draw to rotary sanders. I use a lot of air equipment mainly because it is more efficient but stay with the inline straight type sanders over anything that spins to avoid sanding swirls.

In the wood finishing world they say give all your rotary sanders to the competitors you don't like Ha !
_________________________
J. Christie
Nashville Piano Rescue
www.NashvillePianoRescue.com
East Nashville
Bowling Green, KY
Scottsville KY.
Chamber of Commerce
Member/Sponsor

Putting inspiration in the hands of area musicians
Through restoration/renovation

Top
#2119828 - 07/18/13 08:18 PM Re: refinishing nitrocellulose [Re: Minnesota Marty]
OperaTenor Offline
2000 Post Club Member

Registered: 04/13/06
Posts: 2445
Loc: Sandy Eggo, California
Originally Posted By: Minnesota Marty
Keep in mind that the piano is a 1936 5'6" Kimball in a mahogany finish. None of the 'Polys' would have been used with a finish from that era. Since it shows signs of checking, it would indicate a lacquer finish, as opposed to shellac or varnish. There is no suitable way to use a solvent to 'soften or re-wet' a finish from this era to erase the damage. Spot refinishing can be attempted, but they are visibly noticeable (obvious) unless done by a very experienced craftsman.

The best results are obtained by stripping the entire instrument and then refinish with the choice of any of the modern materials.


Shellac crackles more than any other type of finish. I'm currently refinishing my 1925 Chickering Ampico A, which had a horribly crackled shellac finish. So far, I've stripped the case and the lid; the wood underneath is gorgeous. And, my 1921 Hamilton Manualo has the same ugly old finish.
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#2119849 - 07/18/13 09:06 PM Re: refinishing nitrocellulose [Re: berninicaco3]
Nash. Piano Rescue Offline
Full Member

Registered: 12/08/09
Posts: 386
Loc: East Nashville,TN Scottsville...
Shellac gets a bad rap sometimes but they still use it to seal M&Ms it is non toxic. You can use it as a sealer against Silicone contamination over sanded primer if doing solid colors.

If you are really good and like to curse a lot there is always Vinyl Sealer which is what most cabinet shops use to seal out impurities. I think you could spray that stuff over a leaking quart of oil and get a flawless paint job on it but the issue with Vinyl sealer is if the batch is old it can crack after it dries under your finish.

I still do it the old way. Dye the wood with transtint mixed with water, sand, grain fill, stain, then 3 - 4 coats of sanding sealer sprayed on, block sand 320 - 400 then shoot the clear and rub it out if it needs it. With solid colors it just depends on how wild the paint job gets as to how we build it out.
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#2119898 - 07/18/13 10:47 PM Re: refinishing nitrocellulose [Re: berninicaco3]
OperaTenor Offline
2000 Post Club Member

Registered: 04/13/06
Posts: 2445
Loc: Sandy Eggo, California
I happen to really like shellac. I'm going to use it to refinish my Chickering.

A trivia question: Without googling, does anyone here know where shellac comes from, and was it is?





Edited by OperaTenor (07/18/13 10:47 PM)
_________________________
Happiness is a freshly tuned piano.
Jim Boydston, proprietor, No Piano Left Behind - technician
[url=www.facebook.com/NoPianoLeftBehind]www.facebook.com/NoPianoLeftBehind[/url]

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#2119903 - 07/18/13 10:54 PM Re: refinishing nitrocellulose [Re: berninicaco3]
Minnesota Marty Offline

Platinum Supporter until October 5 2014


Registered: 05/15/12
Posts: 7439
Loc: Rochester MN
Secretions from the Lac bug.
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Marty in Minnesota

It's much easier to bash a Steinway than it is to play one.

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