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Roger Hill

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  1. I had resolved that I was through posting here, being tired of the belittlement that my posts seem to draw, but in order to help someone else here, The following is an excerpt of a file I keep with what to me is interesting violin related information. These passages from Manfio were posted by him starting in 2002. I was not precise in saving the dates. Manfio ground: I would like to know a bit more about the problems frequently mentioned with Sacconi`s silicate. I`ve been using it without problems, and Mastro Marchini, of Rome, told me he uses it too. I just change the form of preparation. I take 1 kg. of wood ash and make it boil in 2 liters of water for 2 hours (as mentioned in the book Preparazione del Legno, edited by cremonese serie Quaderni). Then I wash the instrument with water and a rag, to take off the excess. Then I use the white egg, honey, sugar, water and arabic gum described by Sacconi, followed by my oil varnish (that is not the Sacconi receip) . I`m using this method for more than 12 years without problems. I made some good instruments with this method (including good apreciations by Steinhardt and Michael Tree of the Guarneri Quartet, as well from Pinchas Zukerman). So I would like to know more about these problems with silicate... Manfio Varnish Hi! I've just cook some 2 parts linseed oil, 1 part colophony (dark, from Kremer) and one part mastic. Thanks God no fire ignition!!!. I'm using Kremer's alizarin in oil from SINOPIA: 236107 Alizarine Crimson dark in linseed oil I use some alphalt also (roof tar) dissolved in Kerosene, together with the above mentioned alizarin in a strong solution to colour my oil varnish. Kerosene makes brushing easier. I cook the oil first for about 20 minutes, than add the first resin, cook a bit more, then add the second resin and cook more. All cooking may take one hour or a bit more. Hi! The bitumen is the same thing of roof tar. I dilute the roof tar in turpentine to thick honey like consistency, then I dilute it again with kerosene, add some Kremer's alizarin (this one, in oil, don't need any mulling), I do all that by eye, but it has an strong colour, then I add it to the magister varnish till I get a consistency of spirit varnish. This highly coloured varnish must not penetrate in your wood. I described my ground system in the posts you have read, I think. I'm using now an extra fine pumice used by dentists with the Marciana varnish in a paste that is rubbed in the instrument. I imagine that kerosene works with spirit varnishes, but you have to make tests, if it works it will brush more easily, I think. MANFIO, on 07 December 2010 - 02:14 PM, said: Due to some concerns about the use of asphalt - althougth I never had a problem with it - I decided to try another product to make my varnish darker. Eventually I decided to use Kremer's Bone Black in linseed oil 471007, 250ml Glass 13.00 EUR. It is already incorporated in linseed oil, so no mulling is needed. It incorporated easily to DORATURA VARNISH (Magister Products), I just mixed a bit of it directly to the varnish. I used it in my two latest violas and liked the result. I mix a bit of the Bone Black in oil with some Alizarin Crimson Dark in oil (also from Kremer) and add it directly to the varnish and mix, quite simple to use and incorporate to the varnish. Vernice Bianca "Dissolve in a water bath 25 grams of arabic gum in 100ml water, half tablespoon of honey and one quarter tablespoon of sugar. Let it cool. Then beat the white of an egg with a fork till it forms a "snow" and let it stand for 14 hours. Take the liquid substance that forms in bottom of the container egg and add it to the first solution and filter." I have a vague recollection of reading somewhere that this was used as a ground by painters. It doesn't really act as a pore filler. It does dry very quickly. I find that if the surface is then sanded with linseed oil, the resultant finish is very smooth. The surface was completely sealed by the ground, so that the linseed oil will not penetrate the wood. Some characteristics of this ground - the gum arabic is essentially a glue; the protein in the other ingredients, when dry, renders this ground insoluble in water; it imparts a light honey colour to the wood; varnish adheres very well to this ground. As I've mentioned, the stiffening of the wood results in a deepening of the tone and more carrying power WITHOUT necessarily making the sound louder. The sound of a violin treated with this ground is (to me, by now) very characteristic. For purposes of comparison: I once did a major restoration job on a wonderful Claude Pirot violin of 1815. My first reaction when I heard this instrument was: "My, this sounds like one of MY violins!" Washing with Lye quote: Originally posted by: Darren Molnar Hi Giuseppe, this is a very interesting statement, could you tell us more about this? Where did you here about this system? What do you mean by potassa? Thank you for sharing. "The things that demand more time in order to dry, are exactly rosin and sap... In the OM days the potassa was the most detergent used, for every type of application, adding little of lime increased the caustic power of the potassa. Washing the wood in potassa caustic, linfa and the resin will be saponificate, reducing the times of seasoned. Perhaps " ------------------------- Provando e riprovando Only that in my knowledge. We begin from the soap: it is produced by saponification of an oil or fat animal or vegetable using one alkaline caustic substance. In OM Time the potassa (lye) it was used like "soap" for the cloth, shampoo, barber "soap" etc. It was produced by Wood ash in warm water. This solution could and can be used in order to wash the wood saponifing and removes the dirt, the wax, resin, sap, added with calcium increases its caustic power. Lye cleans the wood oxidizes and coloring it in light yellow, more, disinfectant and perhaps prevents woodworm. Finally it contains and it leaves in the wood all the elements of the ash as well as sodio, potassio, calcium, silicon, magnesium etc
  2. Fool of a Took Well Dr. Mark, will you be offering and will I get to comment on a violin model constructed with the various vibration modes of the individual component parts ?
  3. Jeez. I offer an announcement from the chemistry side of the house rather than the physics side and therefor I am a behind the times reporter. No good deed goes unpunished.
  4. https://www.acs.org/content/acs/en/pressroom/newsreleases/2022/october/chemical-clues-to-the-mystery-of-whats-coating-stradivaris-violins.html
  5. “We found a mathematical argument that explains how and why this robust effect exists with any shape within this class, so that the details of the shape are unimportant, and the only fact that matters is that there is a reversal of curvature along the saw.” Location of inflection is apparently unimportant, though its existence is everything. Enjoy https://www.seas.harvard.edu/news/2022/04/physics-singing-saw
  6. Nice work, but keep in mind that the actual arch is the centerline between the top surface which you are creating and the inside surface which you will create when you do the inside surface.
  7. a better animation is found here: http://newt.phys.unsw.edu.au/jw/Bows.html
  8. Look at the spectrum of the sawtooth wave. The string is being driven not only at the fundamental frequency, but also at all the overtone frequencies. The body doesn't need to create the overtones, it simply responds to drive force of the bridge at the overtones in the sawtooth as you would expect of any approximately linear system. Again, look here: https://en.wikipedia.org/wiki/Sawtooth_wave. Again, I will accept my flogging gracefully if wrong.
  9. I think this is correct. Drive any linear system with a pure sine wave and the output will be a pure sine wave. But unless I have missed something, In which case I will be violently flogged, what I believe is that much of the spectrum of overtones results from the fact that the violin is driven by a saw-tooth wave created by slip-stick friction of the bow with the string, and that drive spectrum of the saw-tooth is rich in higher frequency overtones. See https://en.wikipedia.org/wiki/Sawtooth_wave
  10. Thanks, Don. Good explanation. The fact that I can't hear something that (for practical purposes) is not there, is probably not good evidence that my hearing is still ok. My wife may be right.............
  11. I've lived in Colorado Springs for 50+ years and had the pleasure of hearing Zukerman, Perlman, Bell, Barton-Pine, Chang and others perform with our local symphony. Our elevation is 6,000+ feet downtown where all performed. Atmospheric density here is about 1.0 Kg/M^3 compared to 1.2 at sea level. None of the violin super-stars complained of their fiddles sounding funny due to a change in A0. All of them sounded to me just like their recordings, the most likely locations for the recordings being made was in large cities, the majority of which are at sea level. If this makes a difference it will take much better ears than mine to hear it.
  12. Well, Michael, when it comes to violins, anything that pleases you just tickles me pink . Now, where I am coming from is that you could staff the physics and mechanical engineering departments of a PhD granting university with the technical talent that posts here regularly. While I can't speak for all of that talent, I think that I speak for the majority when I say that the part of violin making that we obsess over is the acoustical part, the tone. I think that most of us probably don't give a flip about the subtle curvature of the entry to the helix of the scroll, but we can get completely engrossed about the entry of the curve of the arch as it approaches the rib, something impacting tone. In my naivete, it came as a surprise to me that professional luthiers would not have tone at the top of their list (or even on their list?) of factors defining quality of a violin. Given that that is so, I can live with it. I just won't be showing anything I make to anyone in the market, and that is no great loss to the market.............
  13. Not saying that, only that the meticulous work coming out of China equals that from 18th century Cremona in appearance. If appearance is all you value, there is a surfeit of apparent quality coming out of China. I have a hard time understanding why the comments of professionals here concern only appearance. Age has a way of increasing desirability of violins, my guess is that the better new violins from China start life having appearance equal to those that started life in Cremona 250 years ago. But would any established luthier accept them as equals? If not, why not? Doesn't tone count for something in the market made by professional luthiers, numerous comments neglecting tone notwithstanding?
  14. And based upon that, it is only a matter of 250 years or so until a good quality Chinese import has value equal to today's Strads and Del Gesus?
  15. This thread seems to confirm that professional luthiers can determine the quality of a violin with only their eyes. An amazing development of their senses and skills, ears not required.............
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