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Giovanni Corazzol

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About Giovanni Corazzol

  • Rank
    Member
  • Birthday 02/09/1970

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  • Website URL
    giovannisworkshop.blogspot.com
  • Skype
    gio.coraz.sky

Profile Information

  • Gender
    Male
  • Location
    Atelier Tranin, Lyon, France
  • Interests
    audio electronics and acoustics
    vintage audio effects
    guitar, piano and double bass
    classical, alternative, jazz, progressive rock music
    foreign languages

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  1. Dear fellow makers, I have been living and working in France for three months now. During this time I have started to do a thorough cleaning and inventory of some areas of the workshop. A large cupboard containing many bottles of old varnishes and chemical products has given me some concerns. I have found some products that are well known in the trade, like Potassium dichromate, K2Cr2O7 this was obviously used as a chemical dye - probably for necks. I wonder if some safer replacement exists. Unfortunately, some folders containing notes by the previous owner have disappeared and we
  2. who's the maker of this product? Do they provide application instructions? as my experience with Super Nikco suggests me, this product actually cleans and degreases the varnish surface very efficiently but I don't believe it leaves a protecting coat over it. If this product has been formulated after the traditional popote of the French ébénistes, and based on the safety documentation, it may be just a mixture of distilled water, alcohol (ethyl- and isopropyl-), mineral oil, glycerol, powdered abrasive. The methyl-ethyl ketone may be just coming from the denaturing of commercial ethyl
  3. Don, it's a very good remark you made here. I don't have my notes from my Cremona school years at hand, but I remember some articles from the Catgut Acoustical Society written in the 90s. The main vibrating frequencies from the violin corpus, neck, fingerboard and tailpiece were listed, and the modes were illustrated and placed over a piano keyboard for reference. I don't remember the process that was described in the papers, but it probably was making a set of tailpieces available in different weights and lengths, plus some plasticine and small weights (I have found small metal pr
  4. you will be able to find one as part of a template set - for example: https://www.dictum.com/en/measuring-inspection-instruments-jbo/herdim-outline-templates-5-piece-set-violin-guarneri-kreisler-1733-739403 or https://www.grandiliutai.com/negozio/molds/violin-internal-mold-kit-messiah/
  5. Moving to Lyon, France in two weeks!

  6. Hello Mr Koo! in my experience, basses are like big cats. I don't know if you have pets, but you see, dogs want the toy, cats want the box. I have never seen such a wedge on flatbacks - I wouldn't place a wedge-shaped shim under the post because, even if the fit would be better in one particular point, I expect that there would be a great difference in tension when the soundpost is adusted. It seems to me that basses "like" a looser fit (I mean, the post has to be fitted well but it should allow wider movements). A light chamfer on the top of the post is very useful. We have a relat
  7. Could it be that your customer installed a fine tuner for the A string and the tuner is cutting into the string? I know about the defective Dominant strings but I remember it was years ago. I had a problem with another brand recently. Some Warchal violin strings (Ametyst?) had a tendency to break, and when I met Mr. Warchal at Mondomusica I asked him. He said that he was aware of the problem and that they had just modified the shape of the ball ending because they noticed that when the string was installed with the "trench" in the ball misaligned to the direction of the string, the string
  8. with the P&H Carbon bow, you are planning to use their prepared bow hair hanks, what if you are not satisfied with the quality of the hair they supply? It may be worth trying though, since it's a bow that you can easily re-sell if you don't like it. I have a customer who is a professional orchestra player and touring musician. He bought a series of carbon fibre bows (the Carbondix, which is a popular brand here) , he chose the best two for use in touring and recording studio (yes!) and sold the other ones.
  9. Hello Mr. Preuss. I think I have a similar problem here in Syracuse, Sicily. I have experimented with using a different solvent for shellac-based retouching varnish. Ethyl lactate seems promising. It is sold in Italy as a xylene substitute in cleaning operations but I found that it acts differently from xylene. For example, it's not practical to treat and remove hardened rosin spots on old varnishes with ethyl lactate. But, when mixing pigments and applying retouching varnish, I think that ethyl lactate works well in humid environments. For me, adding a few drops of ethyl lactate to pigments/v
  10. @Goran74 as far as I know the only violin varnish that can be made with colophony without heating it, is Michelman's varnish. The problem with colophony, it' s that this resin is too acidic and has too low melting point. converting it into rosinate can be made in two ways. one is by heating colophony with a chemical like quicklime and this was the method used in the beginnings of the modern varnish industry. a better way is to convert colophony to rosinate by dissolving it in an alkaline solution and precipitating it with a salt solution (alum, zinc sulphate etc.). This method allowe
  11. Antonio Turco, "Coloritura, Verniciatura e Laccatura del Legno" - Hoepli, Milano Italy 1969 (ISBN 88-203-0947-5) Page 237: Poly-resinous spirit varnishes [for French polishing] [some practical examples are cited] a) Seedlac, 120 grams -- Sandarac, 15 grams -- Manila Copal, 5 grams -- Elemi, 15 grams -- Ethyl. Alcohol, 1 liter this book cites other man-made components that were already common in the trade: nitrocellulose and PVA resins - the latter ones were made soluble and clear by adding 10% ethyl-acetate or benzole. Colophony (heat treated) is also cited as a common
  12. I have written a post on my blog also covering my finger planes. For all those who may be interested, here is the link: https://giovannisworkshop.blogspot.com/2020/05/miscellaneous-tools.html I have been using some of my tools for more than 15 years now. It wasn't common for all makers in Cremona to have access to many sources unless we had friends willing to buy and bring home new tools from abroad. Now e-commerce has made a lot of cheap tools readily available, but sometimes the adjustment work that is necessary on cheap tools is not financially acceptable and returning defective i
  13. The finger planes I have made myself are made entirely of brass. I used small sections of a (gas?) pipe and a sole that I connected by brazing with a silver alloy (castolin in Italian). It can be done with minimal equipment but I am aware that not every violin maker likes to do that. Wooden planes are simple to make and they can be basically made in 4 pieces with a bandsaw. After cutting the center section you make the angled cuts for the blade seating and the escapement for the chips and then you glue the two "cheeks" by keeping everything squared and true. You can use pins if you want.
  14. @Nestorvass I see that the opening in front of the blade may be too wide; I believe that if you manage to glue a small plate underneath as Davide suggested, the plane will improve significantly. It is annoying because you will have to find a suitable material (I have used some cut-out from a small company in Cremona where they make brass doorbell plates) then drill and file the new mouth as precisely as you can. A small engineer's file can be very handy for this task. For roughing out, and planing rib stock, etc., making a wooden plane may be an interesting project. You can also make a to
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