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Bruce Tai

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    Stradivari violins, hi-fi audio, music collection

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  1. That's good to know. Is this a recent CT measurement?
  2. The reason I say alum and potash is because they are fuzzy terms but historically accurate terms. Renaissance alchemists named chemicals that way for practical reasons and limitations. Potash (pot ash) can be made from burning wood or grass. Depending on the temperature, it can be K2CO3 and KOH in different ratios. A lot of CaO may be present, but they can be removed by some means. A purer kind of potash can be made from burning potassium tartrate (tartar, wine stone) or burning potassium bitartrate (cream of tartar). The product is called burnt tartar or Alumen faecis, high-purity K2CO3. Alum has many names in medieval texts but dyer's alum is almost always KAl(SO4)2. Ancients knew how to make highly pure synthetic KAl(SO4)2 by recrystallization. They also prepared NH3Al(SO4)2 similarly, also called alum. Natural alum may be KAl(SO4)2 or Al2(SO4)3. Al2(SO4)3 was chemically produced in large quantities in the 19th century for industrial use. I think an entire book may be written about alum's history. I am just giving a very brief summary.
  3. https://www.bormanviolins.com/pdfs/VSAPBormanandStoel.pdf This paper has different measurements for the Titian Strad Density: spruce 0.368; maple 0.579 Weight: top 61.7g (no bass bar); back 93.6g
  4. I can imagine that CT density may be a few percent off. But 48.1 and 66.6 is night and day difference. I have never done violin CT. I wonder how reliable it is. So what is the lightest Strad top out there? Joseph curtin reported 54 and 55.5 grams without bass bar in a Strad magazine article if I remember correctly.
  5. Assuming 550 cm^2 (includes arching), 2.3 mm thick, 0.35 density, that's 44.3 g. Bass bar 4 g -> 48.3 g. Very close to the Titian measurements. Am I more correct this time?
  6. As you can see from our published photos that have been color-calibrated, the answer is no.
  7. So David, what is the area of the violin plate? Is it 500 square centimeter? I am trying to calculate average thickness based on the area. But the area number is difficult to find on the net. What is the average thickness of the Titian top?
  8. Sorry, website glitch. Multiple posts.
  9. Sorry, website glitch, multiple post.
  10. Sorry, website glitch. Multiple post.
  11. Thanks a lot. I have read this thesis before but missed the data. The top is 48.1 g with bass bar with wood density of 0.35. So the average thickness may be 0.24-0.25 mm. That's a very thin top made of low density spruce. And yet it survived well and sounds great. And yet Joseph Curtin thought a 54 g top without bass bar (for a Strad) is already very light.
  12. In a nutshell, the relevant ones are: Minor additives (tens of ppm): copper sulfate, iron sulfate Major additives (thousands of ppm): 1. Stradivari: table salt, potash 2. Del Gesu: alum, lime We don't know the order and application conditions. We don't know about washing or potential baking/boiling steps.
  13. Unfortunately we still don't have publicly available CT data that tell us about the weight, density, thickness, and weight at the same time. It would be important to know if the very thin Strad plates were built wit denser wood. More importantly, CT cannot reveal chemical composition. So we don't know if Stradivari also adjusted thickness according to wood treatment method.
  14. Hi Andreas, Do we know that Poggi used natural wood? Do you think he has any secret?
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