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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. I just got on the VSA website and discovered there is no Table of Contents for "The Scroll." Is there any way we can see the Table of Contents for the most recent journal (as well as the earlier issues)? Mike D
  2. Fred, I would like to see a picture of this stuff. I know you are aware of the history of black oil, maroger's medium, megilp, etc as mediums in the oil painting world.; so, I will not say any more. Have you considered transparent yellow pigments such as W&N transparent yellow? This could be added to a thick linseed oil and rubbed on the surface to enhance the yellow-ness of the ground as well as seal the wood. There are a bunch of transparent and semi-transparent pigments of various yellow hues that would also work since you are putting them directly on the wood. Disclaimer: this is not Strad's or Amati's ground--It's Fred's ground. Mike D
  3. After listening to Echard's lecture, I reread the work of Barlow and Woodhouse. Their Stradivari sample with the particulate layer has no date--in other words, they do not know what instrument it came from. Maybe the early Strad instruments used a particulate ground and Strad moved away from it. I was thinking there was a connection between Amati and Strad, and thus, the Amati instruments might show this particulate ground. Barlow and Woodhouse did examine a Nicolaus Amata of approximately 1660, and they found no particulate layer. But the varnish did not penetrate the wood, either, causing them to suggest that some type of sealer was used. So, no particulate connection with Amati. I have no problem with using gesso as a ground, but it would leave clear evidence of a particulate layer. So, we are left with more confusion, but we now have many methods of sealing the wood, and sealing is the important point. I hope Echard directs some attention to Amati instruments. regards Mike D
  4. The question about proteins starts with Christian at 1:26:21. Thanks in advance Mike D
  5. Thank you, Davide. I found this video very useful. At the end, there was a question about proteins, but I did not understand the answer. I think it concerned whether there were proteins under the varnish. Could anyone help me interpret what was said? best regards Mike D
  6. Rather than yelling for help, it is time to go back to the literature. Bruce Tai wrote a very good review: "Stradivari's Varnish--A Review of Scientific Findings" in J. Violin Soc of November 2009. He has a section on proteins and carbohydrates which you will all find interesting. And yes, Echard has found proteins in a lute, a violin, and a viol. Tai says "In summary, there is fairly convincing evidence that at least a small amount of protein was incorporated into some classic Italian violin finishes." I found a very recent paper of Echard on varnish: "Reconstructing Historical Recipes of Linseed oil/colophony varnishes: influence of preparation processes on application properties." J. Cultural Heritage. September 2017. First author is Sophie Tirat. Colophony goes from 20-66.6 W%, temperatures 170-250 C, and times at temperature of 10-100 minutes. The best varnishes seem to have spent the most time at the higher temperatures. Some varnish which were inadequately cooked appeared to have separated on cooling. Mike E
  7. Let me quote from Nagyvary's review of the Brandmair and Greiner book: "The cross-sections of 7 instruments were stained by fuchsin that revealed the presence and location of proteins..." Greiner is quoted as saying "Stradivari's process began with the application of a thin coat of protein as a sealer, and the protein could have been derived from milk, eqq white, or animal glue. This was in most instances stained brown by an unidentified stain." The idea of a protein sealer is taken seriously. I did not read where Nagyvary dismissed the idea of a protein layer. Mike D
  8. I think the Echard paper you are referring to is the Angewant chemie paper of 2009 where he looks at the Provigny violin varnish at the wood, lower layer, and upper layer--this is Figure 2. (you should all look at it) This is the FTIR spectra. The important region is at 1725 to 1715 wave numbers where he makes a conclusion that an oxidized oil is in the wood. This peak is at 1714 wave numbers in the varnish region and 1720 in the wood. There are only 6 wave numbers difference between what is in the wood (and he calls an oil) and the upper layer (which he calls a varnish). I think this is too close to make such a definitive statement about oil in the wood as a ground. FTIR spectra are not that definitive. What I am saying is this is not adequate evidence to set makers on the path of putting oil into the bare wood as a ground. Mike D
  9. Advocatus Diaboli, you need to look at these X-sections under the high magnification of an electron microscope in order to see the stratigraphy. That is, determining oil penetration depth as well as any other layers. I have not seen any data from Echard or other scientists that points to the use of flaxseed oil penetration as a ground. Can anyone quote any one who has made this observation? Your X-section of the 150 year old wood shows the coloration of the wood that takes place with time, and that will help with coloring the ground layer. In other words, the color we are trying to match comes with time. Mike D
  10. I suggest you all reread the book "Violin Varnish" by Helen Michetschlager--Koen Padding made a lot of progress on this issue. If you are intrepid and also reread Hargrave's book on Basses, you will make a lot of progress in addressing all the issues. This problem of ground never seems to go away. Padding never left any detailed notes. It is my surmise he left this stage out because it was so obvious to him. I think he arrived at his conclusions by studying how artisans treated wood and canvas at the time these musical instruments were made. Mike D
  11. Naptha also known as mineral spirits or lighter fluid is the thing to try, first. I would be careful with d-limonene--some of the instruments have a glue ground and contact with this solvent might lift the varnish without dissolving it. Be cautious. It is going to depend upon the instrument, but naptha is the safest. Mike D
  12. Ask your local library to get a copy. This is a fast and inexpensive way to get a copy. In my experience, the Abstract always has nuggets of information that tease you into reading the entire paper. This Abstract does not have that information. It is important to note (again) that the varnish film is a historical encyclopedia (that is, a collection) of all the repairs and polishing that has been done over the centuries. These studies are disappointing if you are trying to figure out what the maker did. regards Mike D
  13. Don, 3-phase motors voltage are nominally 240 and 400 volts, and even higher. Dual voltages are common. Mike D
  14. For a small grinder like a 6" wheel diameter, a 1/4 HP motor will be adequate. That means it doesn't require a lot of electrical power. Here in the United States we have 110 volts, and the unit Don Noon has posted will provide 3-phase power with 110 volt input. Thus, you do not need the 220 volts input that most of these 3-phase units require (220 volts may not be conveniently located to the grinder). Here in the US, 220 volts is saved for the clothes dryer, water heater, furnace/AC, and electric stove--so every home has 220 but there is usually not an outlet for convenient use. Mike D
  15. David, I do not know the clear answer to your question. Any motor which is single phase and runs at a single speed and has a start circuit is going to be a problem for variable frequency control. If I was trying to do this, I would identify each type of motor in my machinery and then do the internet search to find out if variable frequency speed control is feasible. There are a huge variety of electric motors. The cheaper ones are capacitor start because they have good starting power (but I suspect they will not work for this modification). Mike D