Bruce Tai

Secrets in the wood (Stradivari's maple)

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I recently wrote an article for Strad magazine about our recent  research on Stradivari's wood: 

https://www.thestrad.com/stradivaris-wood-investigating-the-cheminal-composition-of-the-masters-materials/6969.article

It discusses the research paper  (free download) we recently published in Proceedings of the National Academy of Sciences, USA, but in a less technical way, easier for non-scientists to understand.

The relevance of our research to violin making is also discussed.

All my violin publications can be downloaded from my lab web site: 

http://ntutailab.wixsite.com/home/strad  (look for "Secrets in the Wood")

 

Next year we will publish a paper comparing the chemical formulations used by Amati, Stradivari, and Guarneri.

From our preliminary data, it is quite apparent that all three families have been treating their wood chemically, with some variations in their methodology. But why?   

 

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MikeC   

Hi Bruce,  for those of us who are not chemists can you say in simple terms what chemical elements are found in Strad maple that is not in modern maple backs?   or spruce if that was examined also.  

 

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32 minutes ago, MikeC said:

Hi Bruce,  for those of us who are not chemists can you say in simple terms what chemical elements are found in Strad maple that is not in modern maple backs?   or spruce if that was examined also.  

 

 

We have now analyzed many more samples (maple and spruce) than our initial results published in PNAS.

We have often observed increases in these elements in Cremonese instruments, but each instrument shows different combinations:

Boron - probably from borax used as fungicide

Copper - probably from copper sulfate used as fungicide

Zinc - probably from zinc sulfate used as fungicide

Aluminum - probably from alum, we suspect that it was ammonium aluminum sulfate

Sodium - probably from table salt

Potassium - from wood lye?

Calcium - from lime water or wood lye? 

Judging from the patterns in our data, we are now pretty sure that the violin makers bought normal wood and performed chemical treatments by themselves. In other words, Stradivari, Guarneri, and Amati all tried some experimentation on their own. Our oldest sample from Girolamo Amati is already chemically treated. I suspect that Andrea Amati already started this practice. We cannot say for sure what effects these chemical treatments bring, but they are significant enough for Cremonese makers to keep tinkering for over 100 years. Perhaps it was not a secret in Cremona that they played with wood treatment chemistry, but it certainly is a secret for the rest of us who were not in Cremona during its golden period. 

 

 

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1 minute ago, Bruce Tai said:

Judging from the patterns in our data, we are now pretty sure that the violin makers bought normal wood and performed chemical treatments by themselves. In other words, Stradivari, Guarneri, and Amati all tried some experimentation on their own. Our oldest sample from Girolamo Amati is already chemically treated. I suspect that Andrea Amati already started this practice. We cannot say for sure what effects these chemical treatments bring, but they are significant enough for Cremonese makers to keep tinkering for over 100 years. Perhaps it was not a secret in Cremona that they played with wood treatment chemistry, but it certainly is a secret for the rest of us who were not in Cremona during its golden period. 

 

 

Is there any documentation that would suggest they were "tinkering" for sound or for appearance or for longevity?

 

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6 minutes ago, Frank Nichols said:

Is there any documentation that would suggest they were "tinkering" for sound or for appearance or for longevity?

 

French scientist Robert Palissy (1510-1590) wrote that “salt improves the voice of all musical instruments,” and he could have been referring to chemical treatments of tonewood for acoustic improvements. But he only wrote down this one sentence around , without further explanation. 

In his essay on “Du Sel Commun,” the last sentence says: Il aide à la voix de toutes choses animées, voire à toutes especes de metaux, et instruments de musique. [Google translator: It helps the voice of all living things, even all species of metals and musical instruments].

Palissy wrote this when Girolamo Amati (1551-1630) became a master maker. So it is possible that such ideas have already been floating around.  

 

 

 

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19 minutes ago, Peter K-G said:

Bruce,

You have probably answered this question before, but is it through out the wood or surface treatment.

 

Frankly, we cannot tell. It is impossible to do extensive sampling to understand the spatial distribution of elements.

The concentration and the consistency would suggest to us that at least some of the minerals entered by soaking the wood. 

 

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Seen through the Time Tunnel.............

"But Messere, the Venetians sold you the entire shipwreck for only five florins!?"

"Yes!  All built of maple and spruce!  Washed up in a handy spot, too.  The fools should have spent more on anchors and less on decking."

"Must be enough wood here to build a cathedral."

"No, no, no.  We saw it up small and sell to liutieri.  Much better markup, and enough to last a lifetime."

"Ahhhh, the Amatis in Cremona, perhaps?  They always pay well."

  "We will retire rich, my friend!" 

:ph34r::lol:

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Sorry if my rolling eyes fall out onto the floor, but I am incredulous that we are back again to the topic of soaking wood for improving tone

I would not be surprised that wood was treated for insects and fungus, but whether this improved tone is not proven. (My own investigations turned up nothing significant with soaking wood.) Also, claims in old manuscripts were often exaggerations or perpetual urban myths. 

 

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Was this treatment found under original varnish? Or just on exposed wood? If the latter, it could have been added later by another luthier perhaps?

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Kimmo89   
8 hours ago, Bruce Tai said:

Boron - probably from borax used as fungicide

Copper - probably from copper sulfate used as fungicide

Zinc - probably from zinc sulfate used as fungicide

Aluminum - probably from alum, we suspect that it was ammonium aluminum sulfate

Sodium - probably from table salt

Potassium - from wood lye?

Next job - Take the same samples from the known Stradivari tools.

You will find all these metals from them.

 

If you rub copper to the wood, you will see what I mean.

 

For examble iron can contain every these materials. And we are talking tools that are made in 1500-1700's.

"Just pour all the scrap metal to melt and start forging."

I would say we all have seen better tools and materials.

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gowan   

Salt coming from human sweat?   If wood had been soaked in sea water wouldn't there be other chemicals as well as salt?  Magnesium, Etc.?

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Kimmo89   

Gowan.

 

Interesting.

Can we take DNA from dried sweat?

We definetly need to take samples from the tools to get to know whos they were.

 

At least my violins gets sometimes nice drops of sweat.

Without talking about the sweaty fingers.

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Thank you Bruce for cracking into this otherwise opaque aspect of classical making!!!

 

 

From my own more reading, I was left with the impression that washes with alum, common salt, and lime milk were each widespread practices in old Italian crafts with many uses.   And that lye found many uses.    Also, ZInc Oxide had a place in the materia.

 

 

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Hi Bruce, 

Thanks for posting info about your research. 

Did you look for silica in any of your sample woods?  I was surprised that there was no mention of silica. Other researchers, like Andrew Dipper,  have found silica likely to have taken an important role in wood prep historically, specifically mica. 

Also,  it was known that the wood was sized and not soaked according to Count Cozio's notes. Are you saying that the amount of mineral saturation indicated soaking and not sizing of the wood had to be used by the Cremonese violin makers?

Did you look for proteins or similar treatments on top of the wood at all? Do you plan to?

Thanks very much. I really get excited about new research in this area. 

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In our first round of analyses we could not measure Cl, S, and Si. 

We are trying to resolve these issues in upcoming experiments.

Can these wood treatments affect the tone immediately? Or can these treatments improve the tone 200 years later, as hemicellulose continues to break down and fiber molecules get rearranged due to vibrations?  We don't have a clear answer yet. 

I don't know if the Cremonese makers only cared about wood preservation when they applied these chemicals. Our data says that they cared about it enough to make the chemical formulation gradually more complex over the span of 120 years. They were tinkering with some kind of goal in mind.   

What I do know is that there were some processes in Cremonese violin making which we knew nothing about, until Joseph Nagyvary made some bold hypotheses and went out to prove them. Nagyvary got some of it right, and we expanded his findings. There is still a lot that we don't understand about how Stradivari made his violins, both in terms of wood treatment and varnishing. Anyway I am not trying to promote any secret, and all of our findings will be published with high academic standards, accessible to the public.

In ancient Chinese guqin literature, writers from the 12th century AD were emphasizing the use of wood over 500 years old. We are the first to truly characterize how wood ages in musical instruments over several centuries. But this is only the beginning.    

 

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Kimmo89   

What is the percentage number of copper compared to other metals?

It is possible you will find these METALS in larger amount from in glue joints like top and back has.

Of course it is possible that the glue has taken  the metals into the wood deep. Also in anywhere else, depending what kind of grounding they used.

 

I remember googling these "Stradivari secrets" many years ago and copper was always there.

And all people were thinking this is some kind of a wood treatment...

 

Have you taken samples of modern Cremonese violins?

The metals does not show up this much in these because tools are harder these days,

Brass is I think the only metal that can be found clearly.

 

 

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20 hours ago, Bruce Tai said:

 

We have now analyzed many more samples (maple and spruce) than our initial results published in PNAS.

We have often observed increases in these elements in Cremonese instruments, but each instrument shows different combinations:

Boron - probably from borax used as fungicide

Copper - probably from copper sulfate used as fungicide

Zinc - probably from zinc sulfate used as fungicide

Aluminum - probably from alum, we suspect that it was ammonium aluminum sulfate

Sodium - probably from table salt

Potassium - from wood lye?

Calcium - from lime water or wood lye? 

 

Except for boron and aluminum, aren't all of these present in human sweat?

Aluminum: Isn't that a common ingredient in anti-perspirants?

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I believe and I may be wrong about this but didn't Strad leave in his will, along with his shop and tools some vats. At this time copper sulfate was widely known as a preservative for wood. Maple will soak up (clear through) something like copper sulfate quickly, with in a couple months maybe even weeks. Spruce, not so much. It will float for ever.  

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2 hours ago, David Burgess said:

Except for boron and aluminum, aren't all of these present in human sweat?

Aluminum: Isn't that a common ingredient in anti-perspirants?

I am pretty sure the old guys didn't use anti-perspirants :) (I guess some modern day person holding it could have contaminated it.)

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22 hours ago, Michael_Molnar said:

Sorry if my rolling eyes fall out onto the floor, but I am incredulous that we are back again to the topic of soaking wood for improving tone

I would not be surprised that wood was treated for insects and fungus, but whether this improved tone is not proven. (My own investigations turned up nothing significant with soaking wood.) Also, claims in old manuscripts were often exaggerations or perpetual urban myths. 

 

I didn't get the impression from Dr. Tai's post that tone was being discussed, or any particular merit of what could have been a classical Cremonese wood treatment. I realize it's an easy leap to make because we're all striving for the beauty and complexity of tone available in some of these antique masterworks, however. 

From reading Don Noon's and others' posts on this forum, I would think the added dimensional stability alone would be worth bothering with some kind of treatment. We could continue to pursue the tone goal through other avenues. 

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Don Noon   

It is tempting (and many people appear to fall into the trap) to focus on the mysterious treatments, added chemicals, and magical properties that result.  However, I have not yet seen the connection.

In digging into the appendixes, the bottom line appears to be an increase of approximately 0.75% by weight of metals in the old maple vs. the new samples.  If it is dead weight, I would challenge anyone to tell an acoustic difference.  Cellulose is not going to be stiffened by this stuff, so the only question is if these added metals can somehow stiffen or polymerize the hemicellulose and lignin.  I'm a skeptic there.

Somewhat glossed over is the natural aging effect of hemicellulose decay and reduced EMC.  That is a comparatively huge known effect... about 4% by weight of dead water, a known damping material.  Any other natural age-relate polymerizing effects (and I expect there are some) are not quantitatively known.

So, bottom line:  I don't see that a tiny amount of metals or salts would do much other than make the wood less appetizing for bug and fungus, although that could help a wooden instrument survive 300 years without excessive degradation.  However, the effects of natural aging appear to be comparatively large acoustic factors.  This has guided what I have chosen to do, which includes some fungicide/pesticide treatments for minimizing harmful degradation, and accelerated aging for acoustic effects.

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1 hour ago, Frank Nichols said:

I am pretty sure the old guys didn't use anti-perspirants :) (I guess some modern day person holding it could have contaminated it.)

I was thinking more of contamination by players. Commercial deodorants containing aluminum-chloride go back over 100 years. But how long has alum been around?

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4 minutes ago, David Burgess said:

I was thinking more of contamination by players. Commercial deodorants containing aluminum-chloride go back over 100 years. But how long has alum been around?

:)

 

Aluminum was invented in 1886(9?) I think Alum is a naturally occurring substance :) Sorry, sitting here bored waiting for the hurricane (Irma) to pay us a visit...

 

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