John Harte

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About John Harte

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  1. The pH of whatever you use to extract colour from the dyestuff material (cochineal beetle, madder root etc.,) will have an influence on the final colour of the pigment. There are other contributing factors including temperatures used at various times within the process, speed with which the precipitate is formed etc., that can also influence final colour. Making a cochineal lake pigment doesn't seem any more difficult than making any other lake pigment. (Madder can be more tricky.) From what you describe, a cochineal lake pigment could give you what you want.
  2. I have also downloaded the Plowden Revealed and am hugely impressed with the whole package. This is a resource of rare quality.
  3. There is a front and back view of a 1958 example (copy of a Francesco Rugeri, 1672) plus a brief chapter on Jacklin in this book: https://books.google.co.nz/books/about/The_Violin_Makers.html?id=Jeu7lQEACAAJ&redir_esc=y
  4. Equisetum can relatively easily be thinned and then attached to various backings. The example in the attached photo works well in the area Mike Molnar has been concerned about.
  5. Another shot of Strad maple showing pores/vessels and medullary. (Ignore the colour! Bad camera settings on my part....) I can possibly post more detailed end grain shots of maple that show the relationship between vessels, tracheids, medullary and grain lines if anyone would like to see that.
  6. Mike, Echard has considered protein presence in more than one Strad (and a range of other instruments). As a starting point, the conclusion in this paper is possibly worth noting: https://www.researchgate.net/publication/47511057_Identification_of_the_finishing_technique_of_an_early_eighteenth_century_musical_instrument_using_FTIR_spectromicroscopy His Ph.D thesis should also be mentioned. Included are papers, some of which provide more detail on protein detection and presence. Future results from the Arvedi Lab may prove interesting. If Stradivari's varnish system is your focus, basing anything on the Sgarabotto sample results may be slightly premature....
  7. Thank you Dave! This is very good information. FWIW I should make it clear that I am not advocating the use of a casein or casein based size and do not use one myself.
  8. @ Michael Molnar I'm not sure whether the stain Brandmair describes is necessarily pore filling. Figure 2 on p.64 of this book: https://www.scrollavezza-zanre.com/en/1690-tuscan-antonio-stradivari-violin/ suggests that coloured varnish layer material is able to and has, in this case, penetrated into pores to a considerable extent. My impression from looking at these instruments is that colour filling pores often relates to the coloured varnish layer.
  9. Scordatura, these are good questions but difficult to answer. You touch on factors that will have a significant influence on how things work or don't. The best that you can do is to try as many options as you can and find what works for you. A casein size can absorb stain. However the concentration and/or thickness, what you use to create the casein size; i.e., quicklime, ammonia etc., the extent to which the casein size has dried/hardened, the type of stain involved, the nature of the wood etc., etc., will all matter. Nitrites are normally applied directly to wood. A casein size might be applied after that if you want to avoid varnish penetrating into the wood structure. Other stains might be best applied after some form of glue size is applied. It depends on what you are using and the look that you are after.
  10. Scordatura, you may find some answers to your initial queries in this thread: https://maestronet.com/forum/index.php?/topic/328546-darkening-the-violin-wood/ A discussion of casein grounds starts on page 3.
  11. Hello Francois, I have probably missed something but am wondering where your measurement of 202mm has come from. All of the published measurements that I have seen for the P1705 LB width are listed as 200mm. A printout of the ms-44 outline on your website is very close to this while 199mm is mentioned for generating your drawing of the P1705. Is the 202mm from the CT scan? John
  12. Excellent photos!! Michael, thank you for posting these!
  13. Colour within varnish can be an influencing factor in how flaming might appear. However I have also seen colour in flaming in worn areas where coloured varnish no longer exists (e.g., red, orange, crimson hues...). Colour temperature of the lighting under which an instrument is viewed seems to be a significant player.
  14. A couple of shots of a c.1738 f-hole. Sorry about the quality (Photos of my old 6 x 4s).