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Scientific investigations of Stradivarius violins--an updated review article


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Regarding the “alum thing”, it is of course, a well known and widely used component in gelatin-based sealer layers. So no prima facie case for holding the front page for that one.

Regrettable that things have got so heated in this thread. But Bruce does seem to have a tendency toward pretty heavy duty over claiming.

I’d be interested to know how possible wood contamination during restoration can be ruled out in these studies.

 

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On 4/19/2021 at 1:39 PM, Bruce Tai said:

Good to know that blind tasting of wine is so unreliable and random as well. One possibility that could lead to random results is that the judges don't have a good memory. Even if they have very sensitive taste, they need a strong memory to be able to compare many wines at once. The reason that some judges are more consistent may be that they have better olfactory memory. A lot of people take auditory memory ability for granted. In blind test, the memory has to persist long enough and intact enough for correct judgements to be made. Has Fritz et al. proven that the judges have good enough memory to carry out the task? Not at all. No positive control in the experimental design.  

Interestingly, wine tasters are easily fooled by wine color. Violin listeners can be easily fooled by louder instrument as well. In the 2017 Fritz paper, all three modern violins are louder than all three Cremonese violins in terms of sound power per unit force applied in mechanical measurements. We don't even know how much louder these modern violins were in live playing sessions. You can argue that wine tasters may eventually tell that the white wine doped with red colorant is actually a white wine in disguise over some time. But with a very quick tasting session he may be completely fooled. So it is also possible that louder violins will sound more impressive in a quick listening session. But over longer periods, the listener may hear the tone quality more clearly. Tone quality (timbre) is an attribute of sound independent of loudness. 

Memory decay and confounding factors are so often ignored by the believers of "blind listening test." Don't take blind tests as gospels of truth. Don't let the blind lead the blind.

To me, one thing is clear from these blind tests though--the tone quality difference between the best modern violins are Strads are not very obvious. We already knew that and the blind tests confirmed it. But then again, what acoustic attributes distinguish the best modern violins from the ordinary professional violins? Blind tests do not answer this question at all. So we need to go back to acoustic analysis to find some possible answers.  

 

There are many varieties of red and white wine grapes and there is some overlap in their wine flavor characteristics so it is not possible to identify with certainty in a blind test whether or not a wine is red or white.

For example I colored a good chardonnay white wine that I had made with tasteless red grape color extract and I was able to "fool" two dozen experienced wine tastes in a blind red wine taste that it was a red wine.  I didn't really fool them--it just tasted like some of the red wines that they've had in the past and they just thought it was another one.

In this case my chardonnay had some toasted oak wood exposure which is often also commonly done with many red wines.  

The opposite can also happen.  This weekend I had a well made oaked pinot noir red wine that I could have easily thought was a chardonnay in a blind white wine tasting. 

So the issue isn't about identifying what it is but rather whether or not it's any good.  Wine tastes can very reliably identify bad, mediocre, and good wines because there are big differences between the groups.  However the differences between good and great is much smaller and individuals have different preferences so there won't be full agreements.  Our preferences also are subject to change depending on lot's things.

One way of beating the inconsistency of judging between small differences is to use many judges which is what Claudia Fritz was doing in her blind violin testing.  

 

 

 

 

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13 hours ago, Bruce Tai said:

Our Cremonese samples ranged from 1619 to 1741. The chemical formulation became increasingly diverse and complex. Do you think it is only for finding better and better anti-fungal anti-worm recipes? Professional violin makers, then and now, don't want to waste time testing unproven chemical treatments and would rather focus on producing more instruments to generate sales.

They had other goals in mind. And they were willing to experiment for a century to meet those goals. Guarneri del Gesu was pretty desperate when he soaked his wood into something like 5% alum solution to get a lot of aluminum ion to penetrate his spruce and maple. That's not  just for anti-fungi. The Guarneri family business was doing poorly compared to Stradivari. I guess del Gesu was desperate for a competitive edge. 

 

To detect aluminum, did you take wood samples deep, internally to the spruce and maple? Surface samples alone do not determine whether the wood was soaked long term. Can someone here tell me how long it takes to soak maple or spruce to a significant depth, say 5 mm? Would a violin business work waiting for the wood to finish soaking?
Also, how many instruments were found to have a high Al content? Which? I don’t remember in my reading that Al was commonly detected.

How were you able to rule out that alum, if verified, was used as a mordant for a colored ground?
 

 

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4 hours ago, uncle duke said:

That may of been me saying the awakening bit, not Bruce Tai.

  Though one will need a cause afterwards one can get a copy of caprice no. 21 {20) 6th line and a good player who can play the music.

  Let him/her play whatever music they want for awhile, put the freshly played fiddle on a rack for testing and take note of what's happening.

  Next, have the player run through that section of the caprice ten or so times.  Now retest.

If it's not called awakening it's gotta be called something.

No, it wasn't you, it was in the article that Tai was quoted, and he was not speaking about "awakenings" of a few minutes, he was speaking of instruments "awakening" over a time frame "as long as a year." 

What I think what you're describing is more "warming-up." 

 

 

 

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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%). 

 

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11 hours ago, Bruce Tai said:

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%). 

 

I can tell you what alum has done to the viking grave wooden artefacts and objects at the Vikingship museum here in Oslo after being treated with it in an early attempt at conserving the 900 year old woood. The interoir has degraded into dust and the objects are held together by the outer linnen oil based treatment. The alum and wood reacted to create sulphuric acid. The ships are not alum treated, however. So they are in better condition.

If we are talking about the same thing there would probaly not have been any violins left if they were alum treated. There are lots of literature on it. «Saving Oseberg» may be a good searching phrase.

having said this. I am very surporised that any serious researcher can believe that 1000ppm of something (1000ppm 1000 particles or molecules in a million) is going to make much of a difference to the acoustical properties of something like a violin. 

Edited by Anders Buen
Spelling correction, and added info on the ships
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2 hours ago, GeorgeH said:

No, it wasn't you, it was in the article that Tai was quoted, and he was not speaking about "awakenings" of a few minutes, he was speaking of instruments "awakening" over a time frame "as long as a year." 

What I think what you're describing is more "warming-up."

My interpretation of that article (since it did mention the hypothesis that some or many of these instruments had been stored without string tension, and recently put back under string load):

My observations are that violins will undergo fast and radical changes when first placed under string load, or after substantial time without string load, when brought up to pitch again. I mostly don't bother playing them when first strung up any more, because everything will be different the next day.

After about a month of string tension, things become much more stable. I haven't been able to observe that these changes differ, whether the instrument is played or not. So could there be some player ego involved with the notion of that the player improves, or "imprints" on the violin?

But I still like to have some playing time on instruments before they go to a potential buyer, just in case. ;)

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27 minutes ago, David Burgess said:

 

But I still like to have some playing time on instruments before they go to a potential buyer, just in case. ;)

What repertoire do you play on them? My ex-boss always used to play “ghost riders in the sky”

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33 minutes ago, jacobsaunders said:

What repertoire do you play on them? My ex-boss always used to play “ghost riders in the sky”

These days, I am much more of a maker than a player, so I don't do this myself.

"Ghost riders in the sky" may be a good choice. But "I wanna hold your hand" may be better, since the Beatles achieved greater recognition, and earned a lot more money than Stan Jones. ;)

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56 minutes ago, David Burgess said:

My interpretation of that article (since it did mention the hypothesis that some or many of these instruments had been stored without string tension, and recently put back under string load):

My observations are that violins will undergo fast and radical changes when first placed under string load, or after substantial time without string load, when brought up to pitch again. I mostly don't bother playing them when first strung up any more, because everything will be different the next day.

After about a month of string tension, things become much more stable. I haven't been able to observe that these changes differ, whether the instrument is played or not. So could there be some player ego involved with the notion of that the player improves, or "imprints" on the violin?

 

Sure, this makes sense. When I have a violin that has not been under string tension for a long time and/or gets a new set-up, I will occasionally take it back to my luthier after a month or so for a tone adjustment if I don't feel it has settled into its core tone.

After string changes, I don't bother playing it for 24 hours. I just keep it out, and tune it to pitch every few hours until the string tension has stopped rapidly changing.

Funny thing about "warming up" violins: I have never heard a player say that a violin sounded worse after they had warmed it up. If it was solely a physical process, I'd expect some percentage of violins to always sound worse after warming-up, but it seems that playing a violin and breathing warm moist air on it somehow magically always improves the sound. 

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55 minutes ago, David Burgess said:

...So could there be some player ego involved with the notion of that the player improves, or "imprints" on the violin?

...

Of course. And there's also the notion that previous owners have imprinted on the violin and that a certain violin is "great" because it was previously played by "great" players.  The comments go even further when it's said that a poor player can ruin a violin.

This paranormal attribution, while endlessly fascinating, is also ludicrous.

Isn't it enough to get a kick/sense of history by playing a violin with a remarkable provenance? Why do players feel a need to add ghosts to the equation?

...and BTW, when Big Name players insist this is all true, it makes one question their reliability.

I realize it's all part of the show, drama, artistry...but I don't see a need to cross the line between reality and fantasy. Reality is interesting enough.

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1 hour ago, Anders Buen said:

I can tell you what alum has done to the viking grave wooden artefacts at the Vikingship museum here in Oslo after being treated with it in an early attempt at conserving the 900 year old woood. The interoir has degraded into dust and the objects are held together by the outer linnen oil based treatment. The alum and wood reacted to create sulphuric acid.

Interesting, I've heard about this. I visited Oslo once but didn't have the time to visit the museum. Those ships were really something!

Followed a documentary once when they recreated one and had it hard tested 

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41 minutes ago, Rue said:

Of course. And there's also the notion that previous owners have imprinted on the violin and that a certain violin is "great" because it was previously played by "great" players.  The comments go even further when it's said that a poor player can ruin a violin.

Those notions could be easily tested, some generous soul should loan Strads or GDG's of known reputation to several of us who frequent The Fingerboard............  [Looks hopefully into the audience.]  :D:lol:

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On 5/3/2021 at 3:21 AM, Bruce Tai said:

Many of you may be wondering what modern science can really do for violin making? 

Scientific research is not about making advanced products or giving instructions on how to make advanced products. When is the last time you bought an advanced product by an academic lab. 

The most powerful thing about science is providing conceptual frameworks.

Allow me to explain. 

The concept of LASER (light amplification by stimulated emission radiation) came from Einstein's prediction of stimulated emission in 1917. The first functional laser was only built in 1960. There is a very long way from concept to reality. However, there is no denying that new concepts can guide us to new achievements. Columbus had a concept of the orient, and the concept the earth being round. So he sailed west thinking that he would reach India.  

So what concepts have emerged from the scientific examination of Stradivarius violins? There are plenty. 

1. There is no secret ingredient in the varnish, nothing beyond the normal stuff that painters and varnishers used, all sold at the apothecary. We are finally sure that it is an oil-resin medium. So no need to worry about mysterious animal bloods or rare plant juices. 

2. The varnishing procedures of Stradivarius was complex, not simple. First smoothing the wood, then sealing the wood, applying the ground layer, and finally color varnish. There is no shortcut for reproducing the visual appearance of Stradivari's varnish.  

3. The varnish is not the magic bullet for favorable acoustics. So Hill, Vuillaume, and Sacconi were wrong. Stradivari's varnish may look special due to his skills and tricks, but it is not fundamentally different from what some copyists have tried.  

4. The wood used by Amati, Stradivari, and Guarneri were treated with diverse chemical recipes. Whatever the intentions or the final effects of such treatments, old masters were clearly conducting chemical experiments. My next paper will show that spruce and maple were both treated. Cremonese simply did not use natural wood (air-dried) for violin plates. 

For those who wish to pursue the recreation of Stradivarius violins, the paths are now much better defined compared to 50 years ago. No need to try the crazy stuff or listen to crazy theories. Scientific data can tell you that Stradivari did not spray the alcohol solution of dragon's blood over nitric acid-treated wood.  Scientific data can provide a conceptual boundary of what can be tried, but that's very different from actual technical instructions.  

Psychoacoustics is a very immature field. Black boxes everywhere. After I published the first formant study of Stradivarius recordings in 2012 in Savart Journal (inspired by Nagyvary's unpublished works), several other groups have started to investigate the analogies between violin sounds and human voices in a quantitative way. I think this may be a useful concept for understanding violin psychoacoustics. But such knowledge is just the tip of the iceberg. There has to be be fundamental breakthroughs in measuring real-time brain activities before we can unlock the many mysteries of psychoacoustics. Regardless of whether Strads are the best, we know that there are super nice violins and bad violins. But we don't understand the acoustics signatures that set them apart. 

Currently there is no good way to link these four different things using available science:

Material properties => Body vibrations => Acoustics output => Auditory perception  

Hence, don't expect modern science to provide instructions on how to build superlative violins. Only great makers will be able to make great violins. I don't know how that works. 

   

It seems that still 30 years ago scientists were driven by the belief that there is one secret which could be discovered, nowadays it goes rather the opposite way and scientists try to proove that there is no secret at all. :rolleyes:

1. OK

2. I don't like the word 'complex'. The process was as practical as it needed to be and follows a down-to-earth logic of a craftsman in the 17th century.

3. To quote in this context Sacconi is in my view wrong. Before Sacconi wrote his book everybody was looking for one varnish secret. Sacconi was the first to say 'Hey folks, if you think there is one secret, you are trying to land on the wrong planet.' therefore he consciously chose the title 'I Segreti (in english Secrets)di Stardivari' So for him the mystery consisted of many secrets which were interlinked to each other. To me he was also the first who tried to boil it down to a concept of making. (Hope this is NOT spinning off into a discussion of the 'mistakes' in the book)

4. I'd say more precisely 'alchemical experiments'. But like the varnish we can't rule out the possibility that those 'ingredients' came from a third party (i.e. the wood dealers) To go as far as viewing GDG in his workshop and soaking wood in alumn solution to compete with Strad is stretching the imagination a bit too far.

I don't see any reason why science should play the role of standing back from engineering products more actively. Especially in the field of chemistry, scientific research could provide manufacturers with tested procedures to get good results. 

 

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18 hours ago, Anders Buen said:

I can tell you what alum has done to the viking grave wooden artefacts and objects at the Vikingship museum here in Oslo after being treated with it in an early attempt at conserving the 900 year old woood. The interoir has degraded into dust and the objects are held together by the outer linnen oil based treatment. The alum and wood reacted to create sulphuric acid. The ships are not alum treated, however. So they are in better condition.

If we are talking about the same thing there would probaly not have been any violins left if they were alum treated. There are lots of literature on it. «Saving Oseberg» may be a good searching phrase.

having said this. I am very surporised that any serious researcher can believe that 1000ppm of something (1000ppm 1000 particles or molecules in a million) is going to make much of a difference to the acoustical properties of something like a violin. 

I was digging into this when I had the idea to treat wood with alumn, too. It seems that the Oseberg relicts from the Viking boat were dipped in a boiling alumn solution in an attempt to stop decay. This was about 100 years ago. In any case the wood was not fresh from the tree. If I remember correctly the chemical transformation to Sulphuric acid is interpreted by the treatment of a hot and oversaturated alumn solution. In those terms I am not sure that a light and cold solution of Alumn will have the same effect on fresh wood. 

For the concentration or lets say homeopathic dosis it certainly does not sound reasonable that it makes a change, but I would not be too quick to dismiss it unless the opposite is proven.

 

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It was incorrectly assumed that saturated alum was good for preserving the wood of unearthed Viking ships. The wood ended up absorbing 40%(? need to check the scientific reports) of its weight in alum. As Buen pointed out, sulfuric acid was generated and basically hydrolyzed what's left of the wood. A big blunder. 

Alum was used by ancient Romans for wood preservation and flame retardation, recorded in writing (need to go to my notes for the author's name). The key is of course the dosage. Eat too much salt, people die; Eat to little salt, people die. But salt is essential. 

I speculate that del Gesu might have thought the right amount of alum was essential, in combination with the other funky things he did. I don't know why he even added some Zr4+ into his wood. At 40 ppm it's not going to do much, probably a contaminant from something else that was fishy and clandestine. 

What can 1000 ppm or 3000 ppm of aluminum possibly do? Good question, Buen. We tested those amounts on cellulosic diaphragms for headphones. They caused enhanced bass response below 500 Hz by 1-2 dB. Nothing huge, but easily measurable. We have not had the chance to test on wood bars. But it shows that mechanical properties can be subtly affected at 3000 ppm of Al3+ crosslinking. We put in 9000 ppm of Na+ and nothing happens.  

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4 minutes ago, Bruce Tai said:

I don't know why he even added some Zr4+ into his wood.

Could he have added something he didn't even know that it exists? Zirconium was first discovered as an an element in 1789. The mineral jargoon contains Zirconium and was apparently known since biblic times, but this is again a pretty far stretch. 

I see all those 'funky' elements found by analysis more or less as contaminants in another product. One thing is sure. Alchemists could do a lot of stuff, but they couldn't test the purity of their products.

Or, depending on the dosis maybe the tree soaked it up from the soil it was standing.

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20 hours ago, Bruce Tai said:

Aluminum ion in alum will crosslink wood fibers via coordination bonds.

You detected Aluminium in rather high quantities, ok, but I have to ask why do you deduct from there that it came from alum? There are other metal salts which come from aluminium. 

To find out for which reason it was used it is always very helpful to find old recipes for wood treatment. So I would rather accept that GDG simply used it for the same reason as Romans. The effect on sound, if there was any, was not intended. 

 

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On 5/1/2021 at 9:47 PM, GeorgeH said:

I will also add that the folklore about instruments "waking up" that Tai posted here is not about an instrument sounding better after 5 or 50 minutes of playing. It is about "Top players often say that it can take them as long as a year to coax the kinds of sound they want out of instrument." See that? "As long as a year." (I also don't really hear "top players" saying this "often.")

So, in typical pseudoscientific gobbledegook, Tai says, "that stress-induced deformations will redistribute water molecules in the wood. 'Although precise measurements are difficult, it is not far-fetched to attribute the awakening of old instruments to these factors'"

Here is something I need to tell you in this context

8 years ago I made a violin with treated wood, first soaking and then steaming. I finished it, set it up and when I played it the first time it didn't sound. (the same day I was VERY BUSY to fumble around with the sound post and bridge using swear words in all the languages I know)) After one week the sound transformed slightly, and after one month I realized that the sound in fact evolves in a way that overtones develop to build up little by little. And after one year it sounded not only very good but had a rich quality which became since the measure for all my violins.

Unfortunately I can't provide any verifiable data for this. And I am definitely not scientifically trained enough to provide any explanation better than 'stretch-in effect'. I know only that the violin needed one year to develop its true sound. 

The fact that some top  players need one year to adjust to a new instrument is a completely different story. 

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16 minutes ago, Andreas Preuss said:

Here is something I need to tell you in this context

8 years ago I made a violin with treated wood, first soaking and then steaming. I finished it, set it up and when I played it the first time it didn't sound. (the same day I was VERY BUSY to fumble around with the sound post and bridge using swear words in all the languages I know)) After one week the sound transformed slightly, and after one month I realized that the sound in fact evolves in a way that overtones develop to build up little by little. And after one year it sounded not only very good but had a rich quality which became since the measure for all my violins.

Unfortunately I can't provide any verifiable data for this. And I am definitely not scientifically trained enough to provide any explanation better than 'stretch-in effect'. I know only that the violin needed one year to develop its true sound. 

The fact that some top  players need one year to adjust to a new instrument is a completely different story. 

Which wood did you steam? 

We have learned that boiling spruce can promote cellulose rearrangement but boiling maple cannot. 

There are fundamental differences between softwood and hardwood. A topic that is underexplored. We are just beginning to explore. 

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22 minutes ago, Bruce Tai said:

We have learned that boiling spruce can promote cellulose rearrangement but boiling maple cannot. 

The time or two I boiled spruce, the rectangular cell structure collapsed.  I never tried boiling maple, but the smaller, more round cell strucure I think could be more stable.

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1 hour ago, Andreas Preuss said:

To find out for which reason it was used it is always very helpful to find old recipes for wood treatment. So I would rather accept that GDG simply used it for the same reason as Romans. The effect on sound, if there was any, was not intended. 

Of course, assuming that the presence of Al is real, Dr. Tai has no proof whatsoever that it was actually put there by del Gesù himself and not by the his wood vendor or even somebody later, but lack of proof never stops him from treating his far-fetched speculations as if they are facts.

The only real "fact" that Dr. Tai has possibly shared is that he found some Al in two (2) tiny "flakes" allegedly from del Gesù instruments.

 

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