Michael Szyper

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About Michael Szyper

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    Munich, Germany

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  1. If that would be the real color that we see on this picture, then it is simply wonderful.
  2. Hi friends, would anybody of you be so kind and could take pictures of the measurements of the conte vitale poster? Since it is discontinued I have hard times getting any info about this instrument. Thanks a lot in advance!
  3. I use the dominant e as a first string up on my instruments. It emulates some kind of a worst case scenario.
  4. How can you prove that a layer consists mainly of substance x and not substance y if a method (EDX) is only capable of detecting substance x? As I mentioned, what I wrote is only an interpretation - i.e. the same what Barlow did with his data. I would like to discuss the methods used in those papers and mainly their weaknesses, because only then we can interpret the data in a better way. I just find it intriguing that the data provided by the publications is not all that different, but the interpretations does. I agree with you that FTIR alone is not sufficient to provide exact resin:oil ratios. Brandmair wrote that the FTIR spectra compared best in the case of 80:20 varnishes. This does not necessarily mean it is definitely a 80:20 mix.
  5. Dear friends, Finally I arrived at a stage where I would like to share and discuss my thoughts about the following publications: B Brandmair, SP Greiner „Stradivari varnish“ J-P Echard, S Vaidelich et al; „The Nature of the Extraordinary Finish of Stradivari’s Instruments“; Angew. Chem. Int. Ed. 2010, 49, 197-201 CY Barlow and J Woodhouse; „Of old wood and varnish: Peering into the can of worms“ JCAS Vol 1 no. 4 (Series II) Nov 1989 pp2-9 First of all, I would like to explain the very basics of the used and discussed methods: FTIR: Fourier transformation of infrared spectra. Objects are irradiated by blackbody radiators. The specific absorption spectrums are analyzed and help to identify especially OH, C=O and CH2/CH3 groups. Scanning Electron Microscope (SEM): Electrons are fired at an object, a very sharp picture is achieved. Conductive coating and vacuum are needed. SEM/EDX: The electrons fired at a sample induce electromagnetic radiation (x-rays) with specific spectra, depending on the atoms. The radiation spectrum is detected and analyzed by its peak distribution. This method CANNOT detect atoms with lower atomic number than sodium. That means, that for example carbon, hydrogen nor oxygen can be detected by this method. (This point will be important later on, since these are by far the main components of colophony and linseed oil) Let’s start with the naked results without any interpretation. 1. Brandmair & Greiner B&G compared the FTIR spectra of fresh applied varnish made by Stephan Peter Greiner to the Strad varnished. Greiner made several varnishes with different oil:resin ratios. The FTIR of Greiners 80:20 varnish (final and applied product) matched best to the Strad FTIR spectrum. UV and vis microscopy could not identify filler-type particles within the ground layer. SEM pictures were not provided in the book. Side note: UV and Vis microscopy can not identify colloidal suspensions of very small particles, they would appear as a homogenic mass. Brandmair also commented about this issue in the pigment chapter. 2. Barlow and Woodhouse This is the only SEM picture provided in the publication, which can be attributed to Stradivari with sufficient confidence. I colored the left side to discern between the different layers. They found a very basic porous layer (red). There are almost no particles penetrating the porous structure. Then there is a ca. 60 µm thick layer (green colored). It appears inhomogenic, with amorphous particles of different sizes between 1 µm up to around 10 µm. A third layer (blue colored) sits on top of that, it is around 2 µm thick and appears quite homogenic. In the SEM/EDX different minerals were found. Please keep in mind, they can not provide information, if and how much of organic material is in the sample due to the method. So, the varnish/resin content within this particulate matter can not be provided. 3. Echard et al UV-Microscopy shows three different layers. The lowest one being the wood, covered with a green-whitish fluorescing layer and the top layer with yellow-salmon like fluorescence patterns. Here are the according FTIR spectra of the three layers. The main difference lies in the OH-band, which is very weak in the lower varnish layer. Echard stated this to be the lower varnish layer, comprising of pure linseed oil. My interpretation of the results You all know the interpretation of the authors, so I left it out. First of all, let us begin with the SEM picture of Barlow/Woodhouse. They state that the bottom layer (red) is wood, the middle (green) being the particulate mineral ground, and the blue colored stratum should be the color varnish, which was in their opinion almost gone (but they stated about the same sample that it had a striking brownish color). If you assume that the middle layer are the varnish layers, the thin top layer (blue) could be a restorers french polish. The middle stratum with around 50-70 µm does not appear way too thin to be a full varnish layer. Barlow/Woodhouse did not perform an FTIR analysis on this layer, only SEM/EDX. Therefore, there is lacking evidence against the middle stratum being a varnish layer without a mineral filler. What if the middle layer (green) would be the actual varnish, for example a cold-combined high-resin low-oil varnish. This would be rather a colloidal suspension of oil and amorphous colophony particles than a solid („firm pill stage“) varnish. You could easily obtain a SEM/EDX spectrum like the one Barlow measured. You still would not know if it is 0,1% Si and 99,9% organic material. So, with the lacking FTIR, the Barlow/Woodhouse results could also fit my interpretation. Echard et al. In contrast did an FTIR of the base layer stating that this would be pure drying oil. I do not disagree with their results, the FTIR fits (if the base varnish has not treated with a lye). If I make a cold mixed varnish and put a drop on a paper, the colophony stays where it is, the oil soaks in the circumference of the paper. So the varnish disarranges - drying oil leaves the varnish and soaks into the wooetd. Et voila, here we have the pure drying oil as a base coat layer in the varnish. After the solvent evaporates, the dissolved colophony may form small amorphous particles surrounded by linseed oil. And what about B&G? They did not found a mineral layer in the base coat and used FTIR AND SEM/EDX. On the other hand, uv- and vis-microscopy would be too low in resolution to show the varnish actually as it is - a suspension of colophony particles and dried linseed oil. I have the lack of a modeled experiment to approve these claims. I would need to apply cold-combined varnish on a well prepared wood and let it polymerize. After a bit of aging, SEM, SEM/EDX and FTIR needs to be done on my prepared samples. If they would match, this could support my theory. Until then this is not more than a humble theory. I would enjoy any comment about this. Michael
  6. I am not sure about that, have to check it. There are reasons to assume that Strad did also cold mix his varnish. As I said before, I want to explain my point a bit more in detail...
  7. Yes, clearly: 80% per weight of heavily cooked Rosin, (weight after cooking), and 20% per weight of cooked oil. Rosin is the major ingredient. yes sir.
  8. B&G compared the FTIR spectra of fresh applied varnish made by Stephan Peter Greiner to the Strad varnished. Greiner made several varnishes with different oil:resin ratios. The FTIR of Greiners 80:20 varnish (final and applied product) matched best to the Strad FTIR spectrum. If the methodology and explanation in the B/G book is correct, it states that 80:20 is the ratio of the final, dried product. I made several 80:20 varnishes using heavily cooked rosin, and it definitely is possible to use this kind of ratio. The more I compare B/G, Echard and Barlow/Woodhous, the more I think that all their scientific results are correct and the huge differences in the Interpretation are not based on the completely different qualities of the examined varnish but just on the Interpretation of the result. I will try to post an overview with citations of the articles and try to bring the different interpretations together in the way I would interpret it.
  9. If you can afford it easily, then it should be the way to go. In this case I would absolutely second the advise of Jacob Saunders. Just out of curiosity, what price range this instrument would be?
  10. Arching (from what you can see), setup (fingerboard), edgework and varnish seem a bit odd to me. Varnish seems to have plenty of dirt inclusions. You might strip the whole varnish and revarnish it, but unless you are really experienced in this kind of work, it won’t improve the look IMO.
  11. Sem/edx is the spectrum analysis and not the em picture. I suppose that brandmair would have shown those pictures if she made them, but who knows. The pictures are no objective analytical method, but imo can be quite useful. It is also possible that the particulate layer detected by the pictures is the actual varnish layer and the upper layer just the fp.