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About Mike_Danielson

  • Birthday 10/22/1942

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    Materials scientist--PhD

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  1. They appear to be metal pins which means the glue joint is weak between the pins and the wood. This is not the way this tip repair would be done today, and it violates all the modern rules of repair since you want the reinforcement to be as close to the tensile axis as possible to prevent the crack from re initiating. As is said. "let sleeping dogs, lay." I cannot see the glue crack; so, the crack was correctly closed and the evidence of a break gone except for those pins. Without the pins, you would not be able to know there was a repair--which points out the danger of buying a bow with repairs well-concealed. I would play it happily until there is an accident and the crack reopens--then it can be repaired again in more modern ways (but probably without the metal pins which would be removed) Mike D
  2. As I recall, this was a piece of clear packaging tape applied to the side, near the neck. Since this is on the back, I do not recall a fix for this using tape. Does he want some restoration of the varnish or just protection? That will determine what to do next. Here is a simple idea for just the finish: use an air brush to spray shellac over the area. Now here is the trick--put the instrument in the UV box and subject it to overnight UV treatment. This will set the shellac. Repeat as needed to get adequate build. Shellac hardens under UV and gains wear resistance. Can be repeated indefinitely. Your choice as what type of shellac to use, but for maximum wear resistance, use dewaxed. Mike D
  3. I insert a 1/2" dowell in the neck/root of a new cello. You can set the overstand on the button--this dowell stabilizes the neck. AS far as wolves on A and D, look for the resonance region on the treble side of the instrument. If you use a Krentz unit, insert it below the soundpost and experiment with the position. The wolf is probably on the G-string as well---fix that with a weight on the afterlength.
  4. Difficult to know where the problem lays. Contaminated varnish? Contaminated violin surface? Maybe the work bench is contaminated. Strip the finish off and start again. Test the ground and varnish on another piece of wood--multiple coats before going back to the instrument. May have to toss the varnish. Shellac cures all problems. Wash your hands before working on the instrument. I had this problem (fisheye) on a piece of furniture--my response was to immediately wipe the finish off before it had dried using solvent. Gave the surface a quick wash coat of shellac, and "Bob's your uncle", the problem went away when I recoated it. Mike D
  5. John, it looks like you killed the conversation by introducing some useful technical information. I appreciate your efforts. For those who do not want to read the technical paper of Tirat, let me mention that she has found about 400 varnish recipes over 3 centuries of varnish data. These recipes have as a fundamental characteristic a composition of a drying oil (linseed) and colophony. She includes detailed recipes for 12 in her paper. So, it is pretty well established what these historic varnishes have to be. And a reasonable composition (but it does vary all over the place) is equal weights of oil and colophony cooked to a very high temperature. She could not go above 250 C in her laboratory. The varnishes are thixotrophic which is very useful if you brush.
  6. The quotation comes from "The Wolf Man" movie of 1941. The old gypsy woman foretells what will happen to Lon Chaney, Jr. I left out the part about when the wolfbane blooms he will turn into a wolf and kill. Mike D
  7. Varnish making is simple and inexpensive if you use a recipe like Hargrave's. Cooked flaxseed oil with a resin (colophony, for example) has been used for centuries, and they have a known track record. See Mrs. Merrifield's book. The uncooked rosinate varnishes like Michelman's are a failure. This is well established. The long term performance of cooked rosinate varnishes is unknown. And I suspect they are very hard (not as flexible) as the Hargrave-like oil varnish. Long term stability of the color is also an unknown--all that iron in the iron rosinate could be a problem, and use of madder has a well-known problem with color stability. I would worry that the varnish will eventually alligator or breakdown as in flaking. ASTM has published methods for rapidly testing varnishes for long term performance--this should be done to this new type of instrument varnish to help establish some kind of confidence. But maybe, because you guys are "pure of heart and say your prayers by night", these potential shortcomings will not occur. Mike D
  8. I am curious--what is the recipe? Mike D
  9. On the rare occasions I make this repair, I use a knife to score a cut down the center, widen it with a very sharp edge triangular file, followed by a narrow hand sand, followed by a wider hand saw. I use a wood of close annual rings--sometimes cherry, sometimes maple. I have used elm, a wood that is supposed to be very split resistant. The watercolor box can help hide the repair. The reason you have the grain cross the tip of the break (like Rico shows) is due to a fracture mechanics principle--you must prevent a crack from ever initiating. Rico, I wish you had gotten the crack to close tighter. Mike D
  10. Thanks for the information--the first time I read this, I was still in my cradle.
  11. Cameron, make your own stuff--it is simple. Follow Roger Hargrave's bass book recipe but take it up to 300 C; so the process is over in 1-2 hours. Time is determined by the color density you wish. You will get a red-brown varnish in any case. This recipe is a variation of the recipe in Mrs. Merrifield's book which goes back a few hundred years. Long term experience is what you have to depend upon for long term stability of the varnish. Add turpentine to thin and a few drops of Japan Drier before application. If you look at issues of The Strad magazine of a hundered years ago, you will find venders for Strad Varnish. These suppliers are long gone--wonder how that warranty held up. Watch out for cold varnishes--they resemble megilp which is famous for its ultimate failure. If interested in varnishes, look at the data on what oil painters have used over the centuries--They are the ones with long term experience on how this stuff holds up. By the way, ASTM has methods of determining the stability of coatings, varnishes, pigments, etc.--none of the modern violin varnish has been subjected to this testing for stability; so, it is all a guess. Mike D
  12. Brown needs to give us more information. Something gave it a deep gouge and then there is some dirt in the bottom. Anyone's guess--cryptic from the OP. As far as the varnish is concerned, this is what happens when you put too much pigment in the varnish--muddy.
  13. LL1985---I had this problem on a cello I made. It was a copy of the Andrea Amati of ca 1550. Wolf at F on the A-string was not controllable with the usual methods. The usual method being if you can control the wolf on the D-string, it will disappear on the A-string, but this did not happen. Here is what I did to solve the problem: I use a Krentz-type eliminator, but I put it on the Treble-side of the instrument about 8 cm below the f-hole. Note, this type of eliminator is normally used on the bass-side. There was still the usual wolf on the D-string but a brass thingy on the D-string afterlength took care of that. I use 35 grams of rare earth magnets as my version of the Krentz eliminator. I buy magnets that are 1/2 inch in diameter but at a couple of different lengths so that the smallest magnet is on the outside to hold the thing in place. And I use some cork on the outside magnet to prevent varnish damage.
  14. Rehaired a Glasser carbon fiber bow the other day. It had a plastic frog. Thought about this for a while--used one drop of medium thick superglue on wedge. I use hide glue on wood frogs. Mike D
  15. Give it a french polish. It will fill the scratches and give the right level of warm shine.
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