Advocatus Diaboli

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About Advocatus Diaboli

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  1. If you compare old and new polish, you really have two separate things going on that makes it hard to duplicate. The first is the oxidation and incorporation of grime over centuries of use. The second is that wear that happens to the polish itself.
  2. Along those lines, but with a more powerful vacuum and film. My thinking was that if you were forming a mostly finished arch you could start with a much thinner piece of wood, which would make the bending process much easier. Pressure steaming, maybe?
  3. These are from several years ago. Normally I take photos with a decent camera.
  4. Crappy iPhone4 photos, but here are some shots of other A Amati instruments.
  5. That’s been my interpretation of what he was saying.
  6. That’s not very helpful if you aren’t sharing what you think the stain is. Echard has done much more research since his 2009 paper, and although to my understanding his findings have evolved slightly, there aren’t any significant changes in the findings. I know John Harte and maybe others have been in touch with him and other researchers. I’d love to hear what they have to add.
  7. Echard is the one who’s repeatedly found what appears to be linseed oil in the first few Cell layers, presumably as a ground. SEM would be great if I were interested in trying to see how deeply trace amounts penetrated. From a practical standpoint, however, it’s pretty easy to measure the depth of saturation under UV using a light microscope. If we’re worrying about compounds in the wood, I’d be a lot more worried about salt from sweat than I would be drying oils. I suspect most, if not all violins have sweat from the maker in the wood, but not enough to really affect anything.
  8. I thought I’d take some macro photos of different bits of wood I have lying around to add to the discussion. These are (except for the maple) saddle cutouts from my instruments I’ve saved on a board for times like these. All of them have prepared linseed oil as the ground. The maple is a scrap I smeared about 100 microns of oil on a month or so ago to test a new batch I had made. It’s been tough and insoluble for the last three weeks. To try and get it to penetrate further, I stuck it in the oven for an hour before I took the pictures. It didn’t have any affect that I could tell. This sample is from a top with c.150 year old wood. The maximum endgrain penetration was about 250 microns. This sample shows quite a bit of stain penetration. The wood was cut in the 1980s. No measurable oil penetration that I could find, although the stain had saturated it pretty well. This last one was wood I cut a few years ago, and has minimal penetration of both stain and oil.
  9. Doesn’t that apply mainly to heavy coats of oil, or oil with poor drying properties?
  10. I have no idea why it might matter, but I doubt it does even matter. Some of my favorite sounding instruments that aren't Cremonese have very different mass distribution, and you wouldn't know it from the sound or the way they play. Could be an accident the Cremonese ones ended up that way, could have been on purpose, but more and more I think it doesn't make any bit of difference. I take notes of it on my own instruments, but I haven't seen anything resembling a correlation of how they sound or play... For those interested here are the mass distribution profiles of the Kreisler Del Gesu plates. Mensure 196mm. Soundpost center 202mm. Center of mass top 196mm. Center of mass back 203mm. All measurements taken in 2D from the scan.. The big blip on the top profile is part of the soundpost.
  11. I know Bruce has mentioned before that the balance point is in front of the mensure and soundpost, but I didn’t take that to mean they were inconsistent, just balanced north of the stop. He’s spent more time with fresh examples than most, though, so I’d trust whatever he had to say the most.
  12. The b1+ is around 490, if it’s the twin peak below 500 (that’s my suspicion)... The top arch is around 15.5. Mid 18th century violin.