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Scientific investigations of Stradivarius violins--an updated review article


Bruce Tai
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Although I haven't actually visited it (don't need it for my work, missed signing up for a tour ^_^)...I live down the road from a synchotron.

It's a new technology.  When ours opened, no one knew quite what to do with it so they were inviting anyone who could think of any use for it, to use it, in part, to start to generate a useable data base.

So...in part...just using the technology provides valuable information.

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1 minute ago, GeorgeH said:

So this is the point - one cannot assume or “be sure” of anything because we don’t know and Dr. Tai hasn’t said. This is why discussion of methods and materials is critical information in any presentation of scientific data. What we don’t know includes:

  • When were the samples were obtained?
  • How were they were obtained?
  • What specific violins did they come from?
  • What specific locations on the violins did they come from?
  • Where did the control samples come from?
  • How were the samples stored?
  • How long were the samples stored?
  • What containers were the samples stored in?
  • How were the samples prepared for testing?
  • How were the tests performed?
  • How many tests were performed on each sample?
  • What is the experimental error of the tests on these specific kinds of sample, e.g. accuracy and precision?

And so forth.

Without any of this information, it is impossible to judge the veracity and usefulness of the data or to draw any conclusions from it.

Furthermore, even if the data turns out to be real and scientifically defensible, it is simply impossible to say if Stradivari or Guarneri had anything to do with it. There are other potential and equally likely reasons to explain the results that have nothing to do with either one.

I would say none of the research papers I have read shows anything of the first 8 points in the list you show above. In the past I was mostly puzzled by the fact that no research on the varnish and ground would mention from where the sample came from in terms of spruce or maple.

For the rest I am sure that Dr. Tai will explain in detail the last 4 points in the upcoming paper.

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Given that neither product was available, you might want to analyze the rouge of the day...or maybe lead make-up instead...

I'll go check...that's before Strad's time...

Rouge yes...lead makeup, don't think so...can't remember what was in henna at that time...

Edit:  Lead sulfide as a 'mascara' of sorts, but not as foundation.

***

By the time Queen Cleopatra came to power in the 1st century BC, Egyptian women had at their disposal a whole rainbow of cosmetics, all of which were made from rocks, minerals, and plants in the region. Cleopatra used the bright green malachite paste of the ancient Egyptians on her lower eyelids.

On her upper eyelids, she used a deep blue eye shadow with gold-colored pyrite flecks, made from ground lapis lazuli stone. She darkened her eyebrows and lengthened her eyelashes with black kohl, a mixture of powdered lead sulfide and animal fat. And for lipstick and rouge, Cleopatra used red ochre, a type of clay colored red by iron oxide.

The Egyptian queen even wore nail polish, made of the reddish-brown dye called henna, which comes from the Egyptian privet tree. 

Taken from:

https://indianapublicmedia.org/amomentofscience/cleopatra-wear-makeup.php#:~:text=Cleopatra used the bright green,from ground lapis lazuli stone.

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20 hours ago, Bruce Tai said:

Andreas Preuss showed me that he can take dried tonewood, soak it, and properly dry it again in the workshop. I did not know that in 2016. 

I have done the same.  However, dried spruce is usually resistant to soaking, and I have needed to use cycles of pressure and vacuum to get liquid to penetrate.  Maple soaks pretty well without the extra effort.

I have not tried green (wet) spruce, but I would think that the existing water would resist being displaced without some method to induce flow through.

Sorry for the slow response... I haven't been keeping up with this thread lately.

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18 minutes ago, Don Noon said:

[...] dried spruce is usually resistant to soaking, and I have needed to use cycles of pressure and vacuum to get liquid to penetrate.  

It takes definitely longer. For a cello top it needed over one year until it stayed under water without weights on it.

Later I realized that in the case of spruce it is not necessary to get it 100 penetrated by the water to do the subsequent steaming process. Now I am actually looking more into pure heat treatment for spruce though I am not able to do your torrefication in a vacuum chamber.

 

 

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22 minutes ago, Andreas Preuss said:

I would say none of the research papers I have read shows anything of the first 8 points in the list you show above. In the past I was mostly puzzled by the fact that no research on the varnish and ground would mention from where the sample came from in terms of spruce or maple.

Very often the restorer removed something, and did not record any details. Each time the knife goes, a flake comes off. Then they all go to a plastic bag. Who knows which flake is from which part? 

Did the owner give consent that the flake could be used for research 30 years later? Probably not. So let's not be too specific about the instrument and the exact location. What if this is violin is up for sale next month? We don't want to expose its repair record. We don't want to disturb the violin business with any research. Leave that to the appraisers, auctioneers, and dealers. Don't ask, don't tell. 

The researcher very often knows very little about the sample details or which instrument it came from. However, if it is coming from a top restorer, we may trust its authenticity. The restorer opens up the violin, then he can see if the instrument is authentic better from the inside than just from the outside. He can see which part is original, which is part is restoration, which part is pristine, which part is contaminated. So we are supposed to trust the top restorer for Strad sample authenticity? Of course. We do trust them for restoring the actual Strad instrument. That means they can be trusted. The restorer gets no benefit whatsoever by providing samples for research.  

Cross-comparing samples from several different sources is important. If they show similarly unusual traits, then it's probably because maker did something funky. In my paper I will provide as information as possible on sample origin while still trying to protect the interest of the owners. Anyone who has a problem with this should feel free to purchase a genuine Strad and donate some wood flakes for my research. Thank you in advance.  

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On 5/4/2021 at 8:08 PM, Bruce Tai said:

Nagyvary had one Andrea Guarneri spruce and made some quick measurements. He thought the Al was added intentionally.  

Forty years later, our data are consistent with Nagyvary's original interpretation. That's called reproducibility. Patience is a virtue. The Guarneri family had a special preference for aluminum. Three out f three, completely independent samples. Grandfather and grandson. Neighbors did not add it. It's very telling. 

All my alchemical studies suggest that alum was the most probable source of aluminum. Is there any other possible candidate?

Yes, there is another possible canditate. Natural aluminium levels in Maple.

https://biocyclopedia.com/index/plant_nutrition/beneficial_elements/aluminum/aluminum_as_an_essential_nutrient.php

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7 hours ago, Bruce Tai said:

Very often the restorer removed something, and did not record any details. Each time the knife goes, a flake comes off. Then they all go to a plastic bag. Who knows which flake is from which part? 

Did the owner give consent that the flake could be used for research 30 years later? Probably not. So let's not be too specific about the instrument and the exact location. What if this is violin is up for sale next month? We don't want to expose its repair record. We don't want to disturb the violin business with any research. Leave that to the appraisers, auctioneers, and dealers. Don't ask, don't tell. 

The researcher very often knows very little about the sample details or which instrument it came from. However, if it is coming from a top restorer, we may trust its authenticity. The restorer opens up the violin, then he can see if the instrument is authentic better from the inside than just from the outside. He can see which part is original, which is part is restoration, which part is pristine, which part is contaminated. So we are supposed to trust the top restorer for Strad sample authenticity? Of course. We do trust them for restoring the actual Strad instrument. That means they can be trusted. The restorer gets no benefit whatsoever by providing samples for research.  

Cross-comparing samples from several different sources is important. If they show similarly unusual traits, then it's probably because maker did something funky. In my paper I will provide as information as possible on sample origin while still trying to protect the interest of the owners. Anyone who has a problem with this should feel free to purchase a genuine Strad and donate some wood flakes for my research. Thank you in advance.  

If I understand you correctly, you don't know with certainty where the samples came from and/or can't say and/or won't say where because the luthiers did not record it, and also because you "don't want to disturb the violin business with any research." 

"Don't ask, don't tell" is not a model for good scientific research. 

Have you asked any of the current owners if you could disclose the origins of these 30-year-old(!) samples? Are any of these instruments owned by the people funding your research?

You apparently also don't and can't know if the wood samples are contaminated, adulterated or treated before or after the instrument was made, mixed with other wood samples and/or dust from the luthiers' bench, placed in contaminated (used) plastic bags, been  contaminated with plasticizers after 30 years, etc. A lot can happen in 300 years, and contamination can be invisible.

I am not sure how you plan to show "unusual traits" are different than some set of "usual" traits because you haven't yet, but I think you need to apply a bit more rigor before declaring that "it's probably because maker did something funky." Given the myriad of alternative explanations, it is perhaps equally or more probable that it was not.

 

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11 hours ago, Anders Buen said:

Or his wife or female players cryed so hard when playing that the mascara with alum floated all over the instrument. 

Nah dude, it was the chemtrails 

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Fritz et al. did not show us which Strads were tested. 

That is totally understandable because we have to respect tthe owners and heed to their interests. 

Mutual respect is what moves things forward. 

 

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41 minutes ago, Bruce Tai said:

Fritz et al. did not show us which Strads were tested. 

That is totally understandable because we have to respect tthe owners and heed to their interests. 

Mutual respect is what moves things forward. 

 

In science, veracity, reproducibility, and full-disclosure are what move things forward. Mutual respect is nice, but not a requirement.

Again, have you asked any of the current owners if you could disclose the putative origins of your samples?

Are any of these instruments owned by the people funding your research?

BTW, Frtiz et.al. had many eye witnesses and collaborators in her tests.

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I am not going to argue the merits of scientific protocol, because of course the scientific method is important - but - it's not always possible to adhere to it religiously.

Are the observations of Linneus and Darwin not science? Do we dismiss their "research" and observations?

Bruce is engaged in early work on this topic. That can help form the basis for future work, which then may follow protocol more stringently.

If no one explored a subject because they couldn't follow an established protocol (that in itself may be problematic because it is also constructed) then we'd still all be subsistence farmers.

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2 hours ago, Bruce Tai said:

Fritz et al. did not show us which Strads were tested. 

That is totally understandable because we have to respect tthe owners and heed to their interests. 

Mutual respect is what moves things forward. 

 

Meanwhile you could do some control studies. Or some basic research into the subject and answer my obvious questions.

You know, basic Biology stuff?

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Many minerals occur naturally in the "extractives" of wood: organic content other than cellulose, hemicellulose and lignin.

The most prominent are calcium, potassium, magnesium and phosphorous. I have seen research where trace amounts of aluminum were detected, but I do not know how that impacts the sampling or testing that was done in this study. Just something to be aware of and to account for with the sampling and testing methods.

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In published papers we describe the funding sources and disclose any conflict of interest. 

My research is funded by Taiwanese taxpayers. The only private funding I had was from Chimei Museum to pay for the open access option. Thanks to Chimei everyone can read the paper for free. 

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37 minutes ago, Rue said:

Well, bouquets to Bruce for handling this 'academic onslaught' of criticism so well.

I'm impressed with his grace under pressure.  :) 

Of course, I'm sure he realizes that there may be worse yet to come, as those of us who are true ladies or gentlemen will save their most venomous rancor for journal "Letters" columns, or the "Club" dining room.  :lol:

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1 hour ago, sospiri said:

The attached file shows that the median concentration of Al in 23 wood chip samples. The median value is 14 ppm. These are very crude wood chips sold in bulk. Noticed the maximum values are often extraordinarily high, indicative of serious contamination. The conclusion of this study is that many commercial wood pellets sold in bulk have serious contamination issues.  

ef300884k.pdf

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On 5/3/2021 at 11:36 AM, Bruce Tai said:

To answer your collective question s about alum. 

Nagyvary already reported aluminum in a Guarneri spruce sample (a filius Andrea cello? I need to dig up his old papers from the 80s). His analysis was not very accurate in terms of quantification due to older instruments. 

We got two del Gesu samples (spruce and maple) from plate repairs (1740 and 1741 instruments). They were taken from the inside, little affected by the varnishing. The spruce had >1000 ppm and maple had >3000 ppm for the flake analyzed. Nagyvary told me that it is easier to soak maple than spruce for full penetration. This cannot be due to spraying alum solution or varnishing. This is due to very intentional soaking before carving the plates. 

Aluminum ion in alum will crosslink wood fibers via coordination bonds. However, such bonds are reversible and hydrolysable. This dynamic crosslinking and ability to respond to moisture changes are extremely interesting. But it is very hard to study dynamic bonding using current chemical instruments. Its effect on stiffness and elasticity may be measured, but we have not done that yet. Perhaps the mechanical properties change quite little, but the fiber arrangements and ultrastructural integrity can be stabilized? We don't really know what it does exactly. You have to study it in combination with everything else that del Gesu did. But I highly suspect that alum is one of del Gesu's X-factors. 

If you use chemical crosslinkers like formaldehyde, I think the wood fibers will be destroyed when it expands under high moisture. Alum is like a semi-reversible glue that holds wood fibers together. I suspect that this will become really important as hemicellulose starts to break down in the maple. After 300 years, hemicellulose has become badly fragmented in maple. Some of it even turned into volatile organic compounds and diffused out (loss of ~20%). 

 

Historicaly and culturally, alum was an important and valued material during that time, associated with the use of colorants and many other aspects of the arts and industry.

In later times, it's also the way a magician could a plant or flowers stiff and brittle.  It's affects on stiffness and material behavior can be significant.  Especially with organic materials that wick up water.

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1 hour ago, Bruce Tai said:

The attached file shows that the median concentration of Al in 23 wood chip samples. The median value is 14 ppm. These are very crude wood chips sold in bulk. Noticed the maximum values are often extraordinarily high, indicative of serious contamination. The conclusion of this study is that many commercial wood pellets sold in bulk have serious contamination issues.  

I am sure that you are not suggesting these are comparison control values for your results.

Several literature reports measuring foliar concentrations of Al in gymnosperms reports concentrations in the same order of magnitude that you are reporting in this thread. It is suggested that  "most pinus species are facultative aluminum accumulators."

One would have to also measure and control for moisture content in the samples in order to have comparative data.

I suppose that one would need to test a large number of control samples from the same geographical locations of the local wood sources during that time period to determine if the presence of Al in violin wood samples is naturally occurring or from human sources. 

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5 minutes ago, GeorgeH said:

I am sure that you are not suggesting these are comparison control values for your results.

Several literature reports measuring foliar concentrations of Al in gymnosperms reports concentrations in the same order of magnitude that you are reporting in this thread. It is suggested that  "most pinus species are facultative aluminum accumulators."

One would have to also measure and control for moisture content in the samples in order to have comparative data.

I suppose that one would need to test a large number of control samples from the same geographical location and time period to determine if the presence of Al in violin wood samples is naturally occurring or from human sources. 

From the link above:

"Although Chenery (11) did not consider gymnosperms to be aluminum accumulators, Truman et al. (14) proposed that most Pinus species are facultative aluminum accumulators." 

Here is reference 14: 

Title-- Effect of varying solution ratios of Al to Ca and Mg on the uptake of phosphorus by Pinus radiata

Summary:-- "Pinus radiata (D. Don) seedlings were grown in nutrient solutions in which phosphorus levels varied from deficient to adequate. In the first experiment, Al was substituted for Ca over the range 0 to 0.4 meq/l and P was applied at two low levels (1 and 3 uM/l). In the second experiment, Al was substituted for Mg over the range 0 to 0.35meq/l and P was applied at three higher levels (8, 32 and 129 pM/l)...." 

When GeorgeH finally decides to discuss actual scientific facts instead of statistics gibberish, he fails to understand the difference between seedlings and mature wood tissues.

It is important to learn how to read scientific literature properly. It is not all that hard if you try.  

 

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2 hours ago, Rue said:

Well, bouquets to Bruce for handling this 'academic onslaught' of criticism so well.  You'll be a stronger person for it! ^_^

No worries. There are many experts reading these forums and they contact me privately regarding useful information and samples. This forum enabled me to connect with many makers and restorers over the past 15 years. This is the distinct advantage I have over many violin researchers, an extended circle of global experts giving me advice. When I come up with new ideas or hypotheses, this circle helps me filter out the impractical and the improbable. I am guided by centuries of combined violin making experience while not having made a violin myself. The expert makers are always learning new stuff, and so am I.   

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