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About Mike_Danielson

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  • Birthday 10/22/1942

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    Materials scientist--PhD

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  1. Mike_Danielson

    The ground ( sealing) of the great masters - which was it ?

    Danube fiddler--most of your questions will be answered if you read Bruce Tai's Review of Stradivari's Varnish. I am surprised that no one mentioned it. Be more suspicious of G/B's book and Echard. A great problem of G/B's book is to suggest the idea that the initial varnish is a very lean oil varnish. Read Nagyvary's comments--he is the guy that would know the reliability of the analytical method that leads to this conclusion--and he is suspicious of this conclusion. Your guiding rule should be simplicity. If is complicated, they did not do it. Mike D
  2. Mike_Danielson

    Varnish melting point and repair options

    This is too bad. Pictures would help. Here are several suggestions: 1. Take it to a luthier who will strip and revarnish. 2. Take fittings off and use spray paint to paint it blue. Put stuff back on and play. 3. Do nothing. It becomes a conversation point. Mike D
  3. Mike_Danielson

    The ground ( sealing) of the great masters - which was it ?

    For those that cannot see the advertisement, I pasted a page from a 1900 Strad magazine. It was an Ad for Whitelaw's amber oil varnish that promised that it was "identical to the best Cremona varnishes." I had no idea that there would be a problem that would prevent some people from seeing the ad. The New York Public Library had copied all these old Strads (which are available on-line), and I made a copy of the Ad and pasted it into Maestronet from a Pdf file. Anyway, you can see that the varnish issue has never gone away. There has been plenty of pontification over this issue in the last 118 years. Mike D
  4. Mike_Danielson

    The ground ( sealing) of the great masters - which was it ?

    This might be of interest from a 1900 Strad magazine. Wonder how that Whitlaw varnish worked out over time--but it is the finest varnish in the world. I bet there is a lesson in this. Mike D
  5. Mike_Danielson

    High resin content varnish

    Michael, how do we know that two different varnishes were used? Is there any data in the literature that points this out? Isn't it possible that just one varnish was used, with and without coloring stuff added. Nagyvary says that it is likely that the famous instruments have been french polished many times (over 20 in his quote). That would insure that the outer coat would be a clear, low color of shellac. But depending upon how much alcohol was used and the propensity for the oil varnishes to dissolve in alcohol, the outer layers could be a blend of original oil varnish and shellac. Mike D
  6. Mike_Danielson

    High resin content varnish

    The only decent review of the Brandmair & Greiner (in a scientific sense) was carried out by Nagyvary. And he was very skeptical about the "lean" oil varnish that the authors discovered--saying that the FTIR method was not capable of making this analysis, accurately. With that in mind, I would not put any effort into this lean varnish idea. Rather, I would fall back on the idea of "keeping it simple." That is, the masters used one varnish for the entire work, but they probably added stuff to it (coloring agents) to get the right color or thin layers that were incorporated into the varnish. Nagyvary also mentions that there is a lot of particulates or solids in the varnish (10% in some of the violins)--that sounds like a lot to me. They could have been put into the varnish or directly applied to the varnish coat with a thin coat applied over it--this latter suggestion repeated again and again. I would err on the side of simplicity. Mike D
  7. Mike_Danielson

    Bench lights

    But it directs to another model with the same 45 " arm length. A call to McMaster-Carr might be necessary. This arm length is very useful Mike D
  8. Mike_Danielson

    loss of value in bow after spline

    Edi, does the width of the spline scale with the strength? In other words, if the spline was 1 mm wide would it have 1/2 the strength of a 2 mm wide spline? Edi is correct that there would be a neutral axis when the stress goes from tensile to compressive as you would move away from the tip. The force of the tightened hair is the driving force for this behavior. It would make sense to use less hair in a compromised bow in order to lessen the tensile stress. I think applying fracture mechanics to the problem would also be useful. It is important to prevent a starter crack (notch) from ever forming. The spline sits at just the place you need (maximum stress point of the tip) to prevent that notch from forming. The problem with just a glue repair is if the glue yields at the point of maximum stress, the starter notch will form, and would eventually lead to failure (crack growth and the original glue joint fails). Mike D
  9. Mike_Danielson

    Bench lights

    https://www.mcmaster.com/#1523k22/=1cp27zy This is the one you should replace the Luxo with--it has a 45 inch long swing arm--takes regular light bulbs. $135. I have two of them Mike D
  10. Mike_Danielson

    Pegbox crack

    Let me make different suggestion--use a planetary gear peg since they do not have to be jammed into the pegbox. First glue the crack closed, then ream out hole and insert brown paper spiral bushing, and then ream back to where the gear peg will gently fit. Mike D
  11. Mike_Danielson

    loss of value in bow after spline

    Several years ago, I saw a broken Hill cello bow (silver plate on the tip) for sale on ebay. I cannot remember if it was stamped W.E Hill & Sons or one level below that. It had been repaired with a fairly wide spline (not certain if it was pernambucco), but it had broken a second time through the spline, and it was offered in this broken condition. The spline did not hold the original fracture, closed. I bid on it but lost because it went for about $450, well above what I was willing to pay--I was willing to go to $150. I wanted that bow to see if I could determine why the earlier repair failed--obviously, I thought I could fix it. Was failure due to the use of hide glue rather than new glues? Was it a pernambuco spline which is more difficult to make a good glue joint over say maple or cherry wood splines? The grain of the spline was inserted at the 45 degree angle. I lost track of that bow. There was an opportunity to learn something from this failure. Anyone know if it was repaired? Mike D
  12. Mike_Danielson

    loss of value in bow after spline

    I have mixed feelings about this. An invisible repair means some kind of internal pin that is not visible on the outside. Maybe it will be a permanent repair. There would be a tendency to not report this repair to a purchaser, particularly after the bow has been sold by the person that had it repaired. This is just another level of bad behavior in a business (luthery) that is already filled with bad behavior. Now, when you consider purchasing a bow, you will need to get the dentist or veterinarian to x-ray it. I am still stuck on how well these repairs succeed. My experience is that G-2 epoxy by itself (gluing the break back together, only) is not reliable enough (sometimes, it does not hold--I have seen this for both violin and cello bows)--it need some reinforcement. Which is better--the spline or the pin? Mike D
  13. Mike_Danielson

    Clamp for bow tip repair on a lathe

    It seems to me that a wood dowel would work as well as a carbon fiber rod when at the same diameter, and it would look better. In other words, the wood dowel would have adequate strength and the epoxy would bond to it. If future work was required, the wood dowel could be cut out while the carbon fiber rod would be very difficult to remove. I am interested in the spline versus the dowel repair. Which is better? I have seen splines fail, but have not observed a failure using a carbon fiber rod in the 3 times I have used it, per Edi's method. But I have an open mind on this. I wonder if the splines have failed because pernambuco wood was used for the spline rather than some other wood that has better gluing properties; such as, maple or cherry? In any case,, a spline joint always is visible no matter what wood is used. I have had good success with G-2 epoxy, finding it stronger that any superglue. Edi's data sheet for his superglue indicates that it is weaker than G-2. I am interested in the stress calculations. I have seen violin bow head failures using just superglue to make the joint but success with G-2 which is maybe 5 times stronger in tension. I wonder how much of an improvement in the fracture-joint strength can be achieved with a spline versus just a simple glue joint? Mike D
  14. Mike_Danielson

    Help identifying Hill bow marking

    John Stagg's book on Bows has the code for the Hill makers. Mike D
  15. Mike_Danielson

    Question for purfling makers

    My suggestion: try it for yourself. This is such a simple way to make purfling that you will not invest much time in trying it. The last batch involved Titebond glue to glue the 3 pieces together because it is more thermoplastic than hide glue. It stayed wet for hours in the press. No evidence of bleeding black. This is a severe test for bleeding. Sticking the purfling into water until it comes apart shows no sign of bleeding. Is this enough? Any time someone suggests something new, there is this opposition--well, figure it out for yourself--do some experiments. And while you are at it, think about Hargrave's process: It involves KOH and ferrous sulfate and most of you are scared of chemicals. And then there is the problem of getting logwood--going to find that at the local lumber yard? If you build instruments, you will notice that there is not a lot of variation in purfling sizes that are stocked by the vendors. With an easy process to make a good black, you have much more flexibility in making purfling. Mike D