Preparazione del Mastice e Trementina - Mastic and turpentine refractive ground

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  • Опубликовано: 30 окт 2024

Комментарии • 35

  • @josemauricio8763
    @josemauricio8763 Год назад +1

    Um herói da luteria mundial. Parabéns!

  • @ВиталийВойтович-д9э

    Grazie mille Maestro Dаvidе.

  • @simonecamplani2430
    @simonecamplani2430 Год назад

    Lei sta svolgendo una minuziosa opera documentaristica degna di onoreficenze e studio.

  • @catalinquercinola7553
    @catalinquercinola7553 Год назад

    Once again thank you for another wonderful video!

  • @davidc3808
    @davidc3808 Год назад +1

    Many thanks.

  • @bluehoo0
    @bluehoo0 Год назад +2

    Very interesting and informative video David meany thanks for the demonstration. Does this seal the wood before the application of the varnish, and do you put on one or more coats?

    • @DavideSora
      @DavideSora  Год назад +2

      It is more of a refractive ground than a real sealer, but it also has a sealing effect, especially if you use it at a higher concentration without diluting it too much. One or two coats should be enough, but it depends on the dilution, the degree of absorbency of the wood, whether you first apply other protein sizes, or whether you put it directly on the wood ((it can be used both ways). After application it must not form a layer on the surface, the excess must be removed with a rag leaving just a few microns into the wood. A video on the application coming soon.

  • @ChrisC811
    @ChrisC811 Год назад +1

    Master Sora, thank you as always for sharing your knowledge. My question : I am used to using pure gum artist's turpentine in my varnish. Is turpentine essence the same thing?

  • @albertomendo776
    @albertomendo776 11 месяцев назад

    Gracias maestro! ¿ Have you had any experience with cypress resin, specifically Cupressus arizonica? ¿could it work instead the gum mastic?

    • @DavideSora
      @DavideSora  11 месяцев назад

      Sorry, I'm not familiar with this resin, but pretty much any resin that is soluble in turpentine and has a refractive index around 1.5 would be fine, unless it's too soft, in which case it could be detrimental to the sound because it would cause excessive damping

  • @marcelocavanna8303
    @marcelocavanna8303 Год назад

    Meravglia!!!!!!

  • @camilolutier6173
    @camilolutier6173 Год назад +1

    Grazie Davide. Cercavo questa ricetta da tanto tempo.
    Dopo l'applicazione è possibile utilizzare vernici ad alcool e olio? Quante mani di questo fondo riflettente suggerisci di applicare?

    • @DavideSora
      @DavideSora  Год назад +1

      Va bene sia con vernici a olio che ad alcool. Una o due mani dovrebbero bastare, ma dipende dalla diluizione, dal grado di assorbenza del legno, se si applicano prima altri impregnanti proteici, oppure se lo si mette direttamente sul legno (si può usare in entrambi i modi). Dopo l'applicazione non deve formare strato sulla superficie, l'eccesso va rimosso con uno straccio lasciando penetrare solo pochi micron nel legno. A breve il video sull'applicazione.

  • @karzankarem3198
    @karzankarem3198 Год назад

    ❤❤❤

  • @ghlscitel6714
    @ghlscitel6714 Год назад +1

    surprise - I have exactly the same cooker. I bought mine 50 years ago.
    Maestro, how long is the maximum shelf life of this mixture?

    • @DavideSora
      @DavideSora  Год назад +1

      My cooker also dates back to the time of yours, which is why they are the same. I "stole" it from my mother's kitchen😃
      The shelf life is potentially many years, but due to the turpentine essence reacting with oxygen it will tend to become denser and less drying over time, and will need more time and possibly UV lamps to dry properly. So I prefer to make it in small batches, and to use it within a couple of years

    • @ghlscitel6714
      @ghlscitel6714 Год назад

      @@DavideSora Thanks for the details. How long is the curing time according to your observations on spruce and on hardwood like maple, oak, beech?

    • @DavideSora
      @DavideSora  Год назад +1

      @@ghlscitel6714 I keep the violin for 24/48 hours in the UV box to let it dry well. Without a UV box it is better to wait a week to be safe, but with a UV box it is better

    • @ghlscitel6714
      @ghlscitel6714 Год назад

      @@DavideSora Understand. Found UV curing equipment in the shop of Cremona tools. UVC seems to be the most effective.

    • @DavideSora
      @DavideSora  Год назад +2

      @@ghlscitel6714 UVC is extremely dangerous for your eyes and your health, I do not recommend it because UVA is already sufficient, and much less dangerous. UVC are faster-curing because it is stronger, their wawelength is much higher and therefore much more energetic, but it has a more superficial penetration, while UVA, thanks to its longer wavelength, is able to penetrate a little more in depth. With UVA it takes a little longer, but it works just as well. However, if you decide to use UVC, it is necessary to take absolutely all the necessary precautions, i.e. sealed box with extraction system for the gases produced, automatic shutdown system when the box door is opened and keep the UV box in a separate room from the one you work in (this also applies to UVA).
      For risk-aware use, please read this:
      en.wikipedia.org/wiki/Ultraviolet

  • @BhushanMoretti
    @BhushanMoretti 8 месяцев назад

    Per l'essenza di trementina immagino avrai fatto una ricerca, tra le varie marche, sulla migliore volatilità e minor residuo non siccativo. Potrei sapere per cortesia che marca usi? Grazie

    • @DavideSora
      @DavideSora  8 месяцев назад +1

      Non ho fatto una ricerca vera e propria, l'essenza di trementina Lefranc&Bourgeois ( www.cremonatools.it/lefranc-bourgeois-ess-trementina-rettif-250ml.html ) funziona bene, non mi ha mai dato problemi e non ho sentito il bisogno di provare altre marche diverse. Ma sono sicuro che qualsiasi essenzadi livello "artist grade" potrebbe andare altrettanto bene, escluderei tutte quelle troppo economiche o che non forniscono specifiche adeguate del contenuto. Poi l'essenza di trementina è un solvente che reagisce con l'ossigeno trasformandosi nel tempo, quindi è importante che non sia vecchia o ingiallita, ed è sempre buona cosa fare il test su vetro per valutare se evapora completamente o se lascia residui appiccicosi. Per questo motivo sconsiglio di acquistarne grossi quantitativi in modo da averla sempre fresca

    • @BhushanMoretti
      @BhushanMoretti 8 месяцев назад +1

      @@DavideSora grazie!

  • @colstom
    @colstom Год назад +2

    teacher, when how to apply it to the violin? Thank you very much as always giving high quality lessons

    • @DavideSora
      @DavideSora  Год назад +2

      I apply it after the protein size, but it can also be applied directly to the wood. If you put it directly on the wood it is better to keep it more concentrated to limit absorption. After application it must not form a layer on the surface, the excess must be removed with a rag leaving just a few microns into the wood. A video on the application coming soon.

  • @andrzejtruchan5236
    @andrzejtruchan5236 Год назад +1

    My gum mastic is white is good or needed find yelow color

    • @DavideSora
      @DavideSora  Год назад +1

      I always prefer to use raw resins, to be sure that they have not been treated in any way. The Mastic I use is food-grade. If yours is whiter and lighter, it may have been treated in some way to whiten it and make it more neutral in color. You should try to dissolve it and do a test by drying a few drops on glass to evaluate the drying and transparency properties. You can also find many commercial Mastic and Turpentine varnishes, because it is a very ancient recipe used as a protective varnish over oil paintings, but these are always almost colorless so as not to alter the colors of the painting, while for violins if it is yellower it is better because it increases the contrast of the wood figures a bit more

  • @andrzejtruchan5236
    @andrzejtruchan5236 Год назад +2

    Wen use this ground befor casein

    • @DavideSora
      @DavideSora  Год назад +3

      I put the casein first and then the mastic.

  • @BhushanMoretti
    @BhushanMoretti Год назад

    Molto molto interessante. La colofonia potrebbe andar bene lo stesso?

    • @DavideSora
      @DavideSora  Год назад +1

      Praticamente qualsiasi resina con un'indice di rifrazione (IR) simile a quello del Mastice e un basso numero di acidità potrebbe andare bene. La colofonia si usa ma ha un numero di acidità un po' alto, e andrebbe trattata con una cottura molto più prolungata intorno ai 160° (di solito una settimana) e magari in presenza di sali di calcio e zinco. Il Mastice ha già un numero di acidità piuttosto basso, come anche la colofonia di Larice (trementina veneta), mentre le colofonie di pino e abete vanno trattate e alla fine saranno più gialle., solo se si scurissero troppo non andrebbero bene perchè potrebbero macchiare il legno.

    • @gil_evans
      @gil_evans Год назад

      ​@@DavideSoraWhy is the acid number important (and where to find it for different resins)?

    • @DavideSora
      @DavideSora  Год назад +2

      @@gil_evans If the acid number is high as in the case of pine or fir rosin, the resin will tend to react chemically with the other substances it comes into contact with, changing its color or physical characteristics. If the acid number is low, as for mastic or Larch rosin, or sandarac, the resin will be less reactive and more stable over time, so its behavior is more predictable. There is a specific laboratory test to calculate the acid number, which corresponds to how many milligrams of potassium hydroxide are needed to neutralize the acidity of one gram of resin. This number is sometimes reported in the chemical data sheets of the resins, but not always. It can certainly be found in specific texts on natural resins, a web search usually works