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Soundboard preparation

  • 1.  Soundboard preparation

    Registered Piano Technician
    Posted 04-07-2020 14:55
    Hello all,   I'm looking for advice on an efficient and effective way to prepare an old soundboard for refinishing, i.e. sanding methods, etc.  I've done several in the past, and I've never been completely pleased with the results; sometimes there are streaks, or darker spots, usually up close to the bridges where it's difficult to sand.
    Thanks in advance!

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    Laura Wright, RPT
    Ivory Keys Piano Service
    Durango CO
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  • 2.  RE: Soundboard preparation

    Registered Piano Technician
    Posted 04-07-2020 16:33
    I've only done it twice but advice I received was no sandpaper, cabinet scraper and sharp chisel for hard to reach spots.

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    Larry Messerly, RPT
    Bringing Harmony to Homes
    www.lacrossepianotuning.com
    ljmesserly@gmail.com
    928-899-7292
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  • 3.  RE: Soundboard preparation

    Registered Piano Technician
    Posted 04-07-2020 16:48
    Hi Laura

    Most soundboards are finished in shellac. I use denatured alcohol and lots of old rags to remove the old finish. Use a chisel or screwdriver covered in an alcohol soaked rag to get in all the tight spots. 

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    Willem "Wim" Blees, RPT
    Mililani, HI 96789
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  • 4.  RE: Soundboard preparation

    Registered Piano Technician
    Posted 04-07-2020 18:28
    The very best shellac can be made by taking 190 proof ethanol from the liquor store (Clear Spring or Everclear, not all states allow 190 proof) and adding it to shellac flakes. I found that making it in fairly small mason jars works well, because you need a very tight seal to prevent water from getting into it, and a normal screw lid will be irretrievably glued fast by the shellac. The ring of a mason jar can be removed, however, and the lid can be pried up fairly easily.

    I fill the jar with the flakes, pour in the ethanol to cover, immediately seal extremely well, and warm the sides of the jar in a hot water bath, agitating it now and then. Then I leave it overnight and shake it a little bit if a few flakes at the bottom aren't dissolved yet.

    It's great shellac because 190 proof is so dry. You can also add color to it very easily by putting in powdered aniline dye, which dissolves instantly and has no muddy fillers in it. Or you could use a colored shellac, since some come in orange or ruby versions. For powdered aniline dye, I had very good luck with J.E. Moser's. It comes in a great variety of colors.

    If kept very well sealed, and made from a fresh bottle of 190 proof ethanol, this shellac will last for years.

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    Susan Kline
    Philomath, Oregon
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  • 5.  RE: Soundboard preparation

    Registered Piano Technician
    Posted 04-07-2020 19:10
    Susan

    Laura is asking about cleaning the soundboard. Not finishing it.

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    Willem "Wim" Blees, RPT
    Mililani, HI 96789
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  • 6.  RE: Soundboard preparation

    Registered Piano Technician
    Posted 04-07-2020 22:49
    Yes, Wim, she asked about how to remove the old finish, but you did mention that the most commonly used finish is shellac, and once the old finish is removed the next logical step would be to put on a coat of shellac before or maybe in place of any other finish. So it seemed reasonable to talk about how I've made really good shellac, and how I colored it. I used it to refinish a totally battered celesta using French Polish, so I know it works. I got a lot of social approval from doing that, as I hope Laura would from her soundboard refinishing.

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    Susan Kline
    Philomath, Oregon
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  • 7.  RE: Soundboard preparation

    Posted 04-08-2020 10:09
      I'm looking for advice on an efficient and effective way to prepare an old soundboard for refinishing,  
    She's not just cleaning it.  She's prepping it for refinishing Wim.





  • 8.  RE: Soundboard preparation

    Posted 04-08-2020 10:44

    Thank you for the great detail Susan!

    What rattios do you use when mixing up a batch of shellac?



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    Jonathon Lorek
    Painesville OH
    440-539-7354
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  • 9.  RE: Soundboard preparation

    Registered Piano Technician
    Posted 04-08-2020 12:11
    Thanks, Jonathon

    I don't measure or weigh to get a ratio of flakes to 190 proof alcohol. I just put the flakes in the jar and add enough alcohol to cover. Then once they are dissolved I adjust the solution by adding more alcohol if I think it needs to be thinner. For the French Polish, I kept the initial more concentrated shellac in a tightly capped mason jar, and when I needed a new batch I poured some out (into a clean clamshell from the coop deli), and then I added alcohol and the powdered stain as needed to get a more dilute working solution. Of  course I capped the mason jar the instant I had poured some out of it to prevent humidity from getting in. Be sure that none of the shellac is in the jar thread before putting the ring and lid back on, to prevent the ring from gluing itself to the jar.

    It possibly would be more rigorous to measure, weigh, decide, etc., but this way seems to work and is far less fuss.

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    Susan Kline
    Philomath, Oregon
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  • 10.  RE: Soundboard preparation

    Registered Piano Technician
    Posted 04-09-2020 16:19
    Ah, Susan; you probably, when cooking, only use a recipe for "guidance." Drives my wife batty when I say, "a drop of this a pinch of that, a put in a gloop of. . . " But then she drives me crazy when she uses a tablespoon to carefully  fill a measuring cup, and levels it off-they're only biscuits!!  Yes, a bit of experience helps and shellac is very forgiving. Now Automotive coatings (we can't really call them "paint") are another story! They do require some precision in mixing and application.





  • 11.  RE: Soundboard preparation

    Registered Piano Technician
    Posted 04-09-2020 17:44
    You're right about that ... in fact,, "recipe"? What's that?

    I think of what I've got on hand, and I put it together and prepare it in a way which makes it taste good. Why outsource cooking decisions?

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    Susan Kline
    Philomath, Oregon
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  • 12.  RE: Soundboard preparation

    Registered Piano Technician
    Posted 04-07-2020 21:58

    I always use scrapers on old finishes first. A couple of responses said never use scrapers. I'm not sure why not. A sharp scraper will remove the old finishes quickly and easily without removing wood.  Learn how to sharpen a scraper if you aren't sure. Near the bridge a sharp chisel used as a scraper works very well.  Just work slowly and carefully so you are removing the finish and not the wood. With a sharp scraper a relatively light touch is all that's required.  At the top of the bridge where there's little room to work a chisel is about the only tool that gets you in there. 

    Wipe down with denatured alcohol to remove any residue as then sand lightly with 200 grit and then 320 before sealing with amber colored shellac (dewaxed). Sand smooth after sealing with 200 grit then 400. Light pressure. I usually use slow drying, high gloss, spar varnish as the final coats (2) sanding lightly with 320 or 400 between coats. Two coats is enough. 

    Sometimes the old boards are not so even in color, or aren't well grain marched, and many of the old boards seemed to use shellac or varnish with some kind of darker stain to make the panel look more uniform. Some sections where the grain was more open seemed to take these stains more and can be difficult to get out, I don't.

    I don't like to bleach boards or aggressively sand them which may thin a panel that is already a little weak. However if you are using an epoxy treatment you probably have more leeway there. I don't sweat trying to make old boards look perfectly uniform in color. 



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    David Love RPT
    www.davidlovepianos.com
    davidlovepianos@comcast.net
    415 407 8320
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  • 13.  RE: Soundboard preparation

    Member
    Posted 04-09-2020 04:01
      |   view attached
    This video should make clear my opinion of scrapers.  The trick is knowing how to turn a burr on the scraper blade appropriate for removing finishes. Softwoods are notoriously difficult to scrape because of the alternating hard/soft grain lines. Softwoods are not ring porous so you don't need to use sanding sealer.  Shellac (DEWAXED) is good for surface contamination but dries too fast to brush since the second brush stroke drags up the first. It's easiest to spray shellac.  Almost all the old boards were varnished.    The Stanley scraper itself is over 100 years old. Often old time hand tool techniques are the only way to go.  I've had the same blade for over 30 years.

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    Glen Hart
    Grand Junction CO
    970-434-5558
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  • 14.  RE: Soundboard preparation

    Posted 04-08-2020 06:31
    I seem to do much the same as David Love. Scraper is the magic weapon. In the photos below you can see how nasty this Knabe soundboard looked. But the scraper does a nice job of getting most of the staining out and gets nice and close to the bridge. Turns out okay - and even better when much of it is covered by strings and a plate! I usually use spar varnish, but in this case I experimented with a water-based varnish.

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    Terry Farrell
    Farrell Piano Service, Inc.
    Brandon, Florida
    terry@farrellpiano.com
    813-684-3505
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  • 15.  RE: Soundboard preparation

    Registered Piano Technician
    Posted 04-09-2020 12:05
    Thanks everyone for all the great tips both about prep work and refinishing!

    I've used scrapers in the past, obviously I need to study up on sharpening them!  Terry, what kind of scraper is that?

    One difficulty I can foresee on this soundboard is there are several long scratches across the grain that I'd like to get out.  They look like a cat got ahold of it, although they are under the bass string area!?!

    Thanks again!

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    Laura Wright, RPT
    Ivory Keys Piano Service
    Durango CO
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  • 16.  RE: Soundboard preparation

    Registered Piano Technician
    Posted 04-09-2020 13:04
    Those types of cross grain scratches are probably best left alone depending on how deep they are.  I don't think aggressive sanding is the way to go on an old board and often it just creates more color match problems as the fresher word deeper in the panel will tend to be much lighter in color.  Many of the old boards we see are and were not as pristine as we expect now.  The grain density matching can be all over the place, color matching is often very poor.  If the area is under the bass strings and will be covered by possible not just one but two layers of strings i wouldn't worry about it.  Filling the scratch and trying to match the grain is probably more trouble than it's worth.  It will look "vintage".  Call it a feature of authenticity.

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    David Love RPT
    www.davidlovepianos.com
    davidlovepianos@comcast.net
    415 407 8320
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  • 17.  RE: Soundboard preparation

    Posted 04-10-2020 07:12
    David L. wrote:  "It will look "vintage".  Call it a feature of authenticity."

    Isn't that what they call patina? I think it makes the value go way up!


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    Terry Farrell
    Farrell Piano Service, Inc.
    Brandon, Florida
    terry@farrellpiano.com
    813-684-3505
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  • 18.  RE: Soundboard preparation

    Posted 04-10-2020 07:10
    Laura W. wrote:  "Terry, what kind of scraper is that?"

    I don't know what it is called, but I purchased it from Pianotek many years ago. They have (had?) several different sizes. They work well. That being said, I just purchased a Stanley #82 on eBay (similar to the one in the video posted by Glen Hart)
    ​!

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    Terry Farrell
    Farrell Piano Service, Inc.
    Brandon, Florida
    terry@farrellpiano.com
    813-684-3505
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  • 19.  RE: Soundboard preparation

    Member
    Posted 04-10-2020 12:13
    Terry,  I just bought one myself...its all your fault...I hold you personally responsible <G>

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    Jim Ialeggio
    grandpianosolutions.com
    Shirley, MA
    978 425-9026
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  • 20.  RE: Soundboard preparation

    Registered Piano Technician
    Posted 04-10-2020 17:59
    If you are using something like West System to fill a few cracks, would you do that prior to scraping the old finish?

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    Gary Bruce, RPT
    Bruce Piano Service
    Edmond, OK
    405-413-TUNE
    www.brucepiano.com
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  • 21.  RE: Soundboard preparation

    Registered Piano Technician
    Posted 04-10-2020 21:29
    Yes.
    It works like magic to release the over run from the board.

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    Ed Sutton
    ed440@me.com
    (980) 254-7413
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  • 22.  RE: Soundboard preparation

    Member
    Posted 04-15-2020 21:40
    Glen Hart out there?   This Stanley 82 scraper has a beveled blade...right?  how is the burr turned on a beveled edge?  or is the blade not beveled, and you just turn the burr as in a card scraper?

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    Jim Ialeggio
    grandpianosolutions.com
    Shirley, MA
    978 425-9026
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  • 23.  RE: Soundboard preparation

    Registered Piano Technician
    Posted 04-15-2020 23:40
    https://www.finewoodworking.com/2016/11/10/a-great-mistake

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    Clark Sprague
    Bowling Green OH
    419-352-2198
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  • 24.  RE: Soundboard preparation

    Posted 04-16-2020 18:45
    several more of the Stanley 82 scrapers to be found on Ebay for under $40

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    Petrus Janssen
    Peachtree City GA
    678-416-8055
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