Bruce Tai

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About Bruce Tai

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    https://sites.google.com/site/ntutailab/

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    Taipei
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    Stradivari violins, hi-fi audio, music collection

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  1. Secrets in the wood (Stradivari's maple)

    Some good news to share. I will receive Baroque violin samples from the makers of Rome, Brescia, Venice, Turin, and Bologna. Cross comparisons with Cremonese samples will lead us one step closer to understanding violin making during the Golden Age. I expect the paper to appear next summer. To further understand wood aging in musical instruments, I have been given 500-year-old wood from guqin, and getting >1200-year-old samples is hopeful. A Chinese guqin from 1120 has been auctioned for 18M USD in 2010, breaking the record for Italian violins. I personally do not like this kind of price inflation, but it shows that understanding wood aging in musical instruments can extend beyond European music tradition. Cross-cultural comparison is my next goal.
  2. Secrets in the wood (Stradivari's maple)

    Why wood inside the tree does not age like cut lumber? I think wood inside the tree is not subjected to the same moisture and temperature cycle, oxygen, and light. Why old timber does not work well for making violins? 1. Superior spruce and maple tonewood are rare. If they are top 1%, then a random old beam or cabinet has 1% chance of being useful. 2. Some old beams are internally damaged, losing cellulose crystallinity. We can observe this defect by synchrotron X-ray diffraction on small slices. It is difficult to sample throughout a beam to ensure integrity throughout. Just my two cents.
  3. Secrets in the wood (Stradivari's maple)

    Great point. Weathering involving liquid water, light, and temperature cycles can indeed cause many changes in wood. When multiple factors are combined, the chemistry is far too complex for scientists to investigate using current technologies. Unfortunately, wood is one of the most complex composite organic materials out there. We understand so little even after 100 years of research. Varnish will block most of the UV, I think, making photoreactions much less likely. Lignin is surely going to turn yellow with light exposure over many years.
  4. Secrets in the wood (Stradivari's maple)

    @GeorgeH Playing the instrument is not just generating heat locally inside the wood. The vibration can re-orient the molecules and favorable orientation effects can accelerate certain chemical reactions. This is the entropic term in the equation for Gibbs free energy. Even lifting Scotch tape can generate X-ray or help generate graphene. Mechanical energy can affect chemical bonds in mysterious ways that we don't fully understand. The number of bonds affected may be small and ignored in the short term. But after 300 years there may be an cumulative effect. Vibrating new wood may not do the same because the hemicellulose network has not loosened up yet. In all kinds of science there is NO [edit] absolute proof in most cases. When faced with multiple possible explanations, Scientists follow the principle of Occam's razor: "other things being equal, simpler explanations are generally better than more complex ones." Even in a paper we cannot describe all the possible explanations and how we arrive at our simplified interpretations. When new evidence emerge, we quickly reassess our original interpretation. One may feel free to argue about sampling and authentication issues. But I feel pretty confident that we have been able to largely reproduce Nagyvary's results by getting additional samples from unrelated parties. We have been able to confirm the suspicion of Chinese luthiers that tonewood slowly transform over time over the timescale of hundreds of years. It is a pity that acoustics and psychoacoustics research get little funding and remain so underdeveloped. Building a violin with new wood and old wood with substantial carbon loss in its hemicellulose component should make a real acoustic difference. If we have better acoustics experiments this should be readily testable. Although hard evidence is important for science, I also remind my students that "the absence of proof is not the proof of absence." We all have our own interpretations. A scientist also needs to see beyond current evidence and come up with new models of the reality and then design new experiments to address those. Einstein said: Imagination is more important than knowledge. Nagyvary may have said many things incorrectly. But he was bold enough to open up new chapters in violin research which turn out to be worthwhile. The pioneer who ventures into the unknown is bound to get many things wrong, especially because violin research is a very "soft" science.
  5. Secrets in the wood (Stradivari's maple)

    Here is my reply to Claudia's work, published in PNAS as letter to editor. http://www.pnas.org/content/111/27/E2778.full There was not enough space in my wood study article to go into psychological testing debates.
  6. Secrets in the wood (Stradivari's maple)

    Hi Joe, we recently tired to expose maple to simulated standard sunlight for 24 hours and the infrared spectra changed. As we may expect, lignin absorbs light energy and chemical reactions occur. But the changes due to sunlight are quite different from those in Cremonese maples. I don't think sunlight is a major factor here. With every new type of measurement we understand just a little bit more about what's going on. But no clear picture yet of the entire wood processing paradigm in Cremona.
  7. Secrets in the wood (Stradivari's maple)

    For your information, furfural is the most easily detectable product of carbohydrate breakdown in wood and paper. Old books continuously release detectable amounts of furfural which can be detected by mass spectrometers. I have a mass spectrometer in my laboratory and supervise a core facility with three more. I have been teaching PhD-level bioanalytical chemistry for 6 years in a row. Don't just throw around big words like entropy and statistics and metaphysical questions, as if that's not pseudoscience. Search for furfural, paper, and aging in Google Scholar to learn about the breakdown process of carbohydrate polymers. The mechanisms are quite complex and not fully understood. Today I read a paper saying that for every furfural molecule detected, 9 glycosidic bonds are broken in pure cellulose. That means, in every second, there are multiple glycosidic bonds breaking in cellulose chains inside a violin, leading to depolymerization. This could only be more severe for hemicellulose. Look up the boiling point of furfural and one will realize how carbon disappears gradually from old wood, something we observed in Stradivari violins. Mechanical energy from playing will likely accelerate this breakdown by injecting more energy. With every passing second and every bow stroke, the violin is disintegrating. However, this is a really slow process and it may even bring acoustic benefits (or maladies) during certain phases. Our study was the first to quantify wood chemical changes in old wooden instruments. We produced a rough estimate of hemicellulose half life of 409 years. Actually, half life is a very vague idea here because we don't know the actual breakdown process. But even with imperfect experiments, important new concepts can be generated. In China, the Lei family (8-9th century AD) is synonymous with famous guqin, as Amati or Stradivari is synonymous with famous violins. Lei said that guqin will only develop great sound after 500 years of aging, due to wood changes. I only read this after I published the hemicellulose half life. Chinese luthiers have been making guqin since 800 BC, at least. By Lei's time they have accumulated 1500 years of experience, and hence they have a sense of what may occur after 500 years. Our primitive observations fit well with their opinions, and that is a good start for science to get involved in a 3000-year-old art. Guqin from the 8th century are still being played and restored, and recorded into CDs. Chinese luthiers have been emphasizing the importance of wood aging for 1200 years, in order to achieve good sound. In 12th century AD, Chinese scholars stated that old wood becomes drier over 1000 years, and our violin data support it. I have written a new article in Chinese about how Chinese luthiers made many brilliant observations now supported by our violin data. I only started to read these Chinese books a few months ago, after our PNAS paper was published. Chinese luthiers have been arguing about wood issues, including aging and artificial processing, for 1000+ years. Their opinions are not baseless.
  8. How long does it take EMC to change?

    I am quite amazed that it is so slow. Absorbing moisture is also known to be slower than losing moisture.
  9. Secrets in the wood (Stradivari's maple)

    We already know that heating the wood to degrade hemicellulose is quite different from natural aging. The infrared spectra (IR) of heated wood (several conditions below 200 oC) is quite different from aged wood. The peak at 1650 cm-1 increases in old wood but decreases in baked wood. This affects how metal ions bind to wood, which came from chemical treatments by Stradivari. There are additional differences in IR spectra, too. Steaming for three days has almost no effect. Before hemicellulose is even degraded, baking can induce chemical changes in wood which are quite different from natural aging. I don't know which one is better, but I do see obvious differences in the data we collected. I am sorry that wood chemistry is really complicated and not well understood. Just because Stradivari's maple looks like modern maple, we automatically assume that they have similar properties. But in fact they are quite different chemically.
  10. Secrets in the wood (Stradivari's maple)

    We now have Cl, Si, and S measurements set up on ICP-MS. We will have to see how reliable they are. Boron is a really interesting element. It is generally 5 ppm or so on natural spruce and maple, old or new. In all Cremona samples, including repeated sampling of the same instrument, it is 20-60 ppm. This is remarkably consistent considering how heterogeneous wood can be (heart wood, sap wood, close to vessels, porous areas, etc.). I believe that borax was thoroughly soaked into the wood. We have now several hints that at least some of the minerals were applied by soaking. Others may be applied at the surface. I don't think wood preservatives are applied at the varnishing step. They are probably applied before long-term storage.Wood stain may carry one or two unusual elements, but we have absolutely no idea what this stain is. Brandmair's photos show very shallow penetration of wood stains. So I don't think it can be detected from internal scrapings. We will never know the exact procedure, though, no matter how much chemical analysis is done.
  11. Secrets in the wood (Stradivari's maple)

    We already know that not all violins attributed to Antonio Stradivari were made by him. Some were probably from his sons and his neighbors such as Bergonzi. Anyway they were mostly closely related and represented the same school. Arguing about the authenticity of any single sample does not alter the fact that a collection of spruce and maple samples attributed to Amati, Stradivari, and Guarneri all show evidence of related chemical treatments. There will be an overwhelming amount of ICP-MS data in our next paper to establish this fact. If we find a single sample not showing chemical treatment, we would actually suspect if it is unauthentic. To my surprise, we have not encountered such a sample yet. Kudos to the appraisers and restorers who stood behind these instruments for so many generations. They kept track of things well and worked with great honor and pride.
  12. Secrets in the wood (Stradivari's maple)

    I am starting to wonder to what extent pernambuco wood undergoes hemicellulose degradation and vibration-induced molecular rearrangement, if turned into a violin bow. Pre-treatment of wood, even just extended soaking, may alter the effects of aging and vibration. This is something worth exploring. I wonder if we cane unveil the secrets of antique French bows, if we can get some wood samples from broken bows. But then again, the naysayers are going to argue that there is no proof that Tourte, Sartory, and Peccatte made better bows. Someone can probably organize a blind test and show that Tourte and Kittel bows are no better than current bows entering competitions. It is really easy to design a bad experiment and get negative results. I don't know how to design an experiment to demonstrate the special properties of the famous bows, either. But I do trust the consensus opinion of top violinists over several generations. Their pursuit of artistic perfection totally depends on great bows, which they hold for several hours a day. I have faith in their collective wisdom and my guess is that there could be something special about the wood of these great bow makers.
  13. Secrets in the wood (Stradivari's maple)

    We had maple samples from the inside of the instrument and deep within the neck block. The varnishing outside cannot penetrate so deeply. I am recently told that the inside of Strads may have received some coating to harden the surface, as observed by some violin restorers. This has also been proposed by Nagyvary, who showed an electron micrograph of particles on the inner wood surface. However, there could easily be dust or glue contamination on the inside. I don't know how we can prove the presence or absence of internal coatings. Further opinions from expert restorers are needed to clarify this issue. We are lucky to have a Strad neck sample that can be drilled deeply into untouched areas. Luckily, its measurements match with the back plate Strad samples from other sources. This gives us much confidence about our interpretation.
  14. Secrets in the wood (Stradivari's maple)

    We have already completed the elemental measurements of 10 Cremonese samples, some spruce and some maple. Just a few more to go before we write up the next paper. Every single wood sample from Cremona is unnatural. All have been chemically treated. The same maker uses a similar recipe for spruce and maple. The recipe from Amati, Stradivari, and Guarneri families are clearly different. This means that treatments were not done by wood suppliers, but by makers themselves. Contamination cannot explain our data at all. Cremonese just did not make violins with untreated wood. The Brancaccio Strad neck is real, judging by our data. Its measurements are consistent with those of other Strad samples from different violin shops, by DSC, TGA, NMR, ICP-MS, and IR experiments. This cannot be coincidence and cannot be attained by random maples from the modern shops. I have published a letter to editor in PNAS Journal to criticize the blind tests of Fritz et al. I won't repeat those points like a broken record here. People should not have blind faith in these ill-designed blind tests. No one has the resources to organize better blind tests than those by Fritz et al. I will give them credit for doing the best study possible under practical constraints, but it still is not good enough. Chimei Museum has now 1000 antique violins in its collection, giving musicians and music lovers in Taiwan unprecedented opportunities to repeatedly compare the works of different European schools. The consensus opinions formed by Taiwanese violin circles, as well as many international musicians and dealers who visited, over the last two decades echo those of premium instrument dealers from the past. Apparently, people who have the most opportunities to hear many hi-end instruments side-by-side reach the same conclusions again and again. Gaglianos and Guadagninis were great masters, and so were the famous makers from 19th-century Italy and France, but their best works still cannot compare with the finest Strads and del Gesus. Some people keep arguing that listeners and players are biased by the high price and high reputation. It is a pity that the naysayers do not have the chance to spend a few afternoons in Chimei's vault and listen for themselves. Pick any 20 great makers and compare their works to the 5 Strads and 3 del Gesus, and you will hear that Stradivari and del Gesu consistently win [edit: I should cay "sound better" or "come out on top"]. Should we be surprised at all? Did not all the great violinists and dealers tell us so?
  15. Secrets in the wood (Stradivari's maple)

    Interesting point. I guess my motivation is to disprove that Stradivari did not possess any secret. The null hypothesis is that his wood is nothing special, just wild maple. But its elemental composition is so strange that the null hypothesis has to be rejected. The hard evidence suggests that he treated his wood chemically, and we did not know about it. The fact that we did not recognize chemical preservatives as an integral part of the Cremonese method makes it a lost secret, only to be recovered by modern science. I then wanted to disprove that Stradivari did this trivial trick out of the blue. So I checked Girolamo Amati's wood and it was chemically treated, front and back. Amati had a simpler chemical recipe and Stradivari and Guarneri expanded it by adding more chemical substances. Since we all agree that Amati, Stradivari, and Guarneri were genius makers, this chemical formulation must have mattered a lot for them. So I disproved that (in my next paper) the Cremonese invented violin making based on natural, air-dried wood. They were never into using natural wood, and insisted on applying chemical treatments. I cannot prove its acoustic influence right now, but no one can disprove it either. We don't know exactly how they did it and how things are affected hundreds of years later. Technically we cannot prove anything but only falsify something which is the opposite. But there is no need to get into logical games. In experimental science, we present measured facts and offer logical explanations. Cremonese masters never intended to build their violins using natural wood. This is a historical fact and the proof will be presented in my next paper. Whether or not this new discovery matters entirely depends on each person's perspective. Oh, by the way, I am writing a new paper to show that Andrea Amati and Gasparo da Salo were mimicking the baritone voice with their newly invented violins. Stradivari was able to push it to the alto voice. This is based on formant analysis and it will hopefully be published soon. Geminiani wrote in 1751 that the ideal tone of the violin shall "rival the most perfect human voice." I think Amati and Stradivari were trying to do exactly that.