Gluing the violin back and apply the inside treatment from start to finish

(vedi sotto per la traduzione in italiano)
Place the ribs on the back making sure that the respective center lines match, temporarily blocking the upper and lower blocks with three clamps. Then place the rest of the clamps starting from the four corners, making sure the ribs position corresponds with the contour marks traced on the plate. Proceed with the gluing using hot hide glue, removing a few clamps at a time so as not to change the position of the ribs. Wait overnight for the glue to dry (minimum 8 hours), remove the clamps and drill the hole for the endpin, leaving it a little smaller than the definitive size that will be optimized once the violin is finished. With a sponge apply the internal treatment (casein in my case) spreading it evenly and sparingly, to avoid affecting the gluings. Let it dry thoroughly for at least 24 hours and smooth the surfaces made rough by the swelling of the wood fibers caused by the absorption of water.
Incollaggio del fondo di violino e applicazione del trattamento interno dall''inizio alla fine
Posizionare le fasce sul fondo assicurandosi che le rispettive linee di mezzeria combacino, bloccando temporaneamente i tasselli superiore e inferiore con tre morsetti. Quindi posizionare il resto dei morsetti partendo dalle quattro punte, assicurandosi che la posizione delle fasce corrisponda ai segni della tracciatura sul fondo. Procedere all'incollaggio utilizzando colla di pelle a caldo, rimuovendo pochi morsetti per volta per non modificare la posizione delle fasce. Attendere una notte che la colla si asciughi (minimo 8 ore), rimuovere i morsetti e praticare il foro per il bottone, lasciandolo un po' più piccolo della dimensione definitiva che verrà ottimizzata una volta terminato il violino. Con una spugnetta applicare il trattamento interno (caseina nel mio caso) stendendolo in modo uniforme e con parsimonia, per evitare di intaccare gli incollaggi. Lasciar asciugare bene per almeno 24 ore e lisciare le superfici rese ruvide dal rigonfiamento delle fibre del legno causato dall'assorbimento dell'acqua.
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[@jaminvincent5690]

Complimenti!!!! I tuoi video sono di altissima qualità. É come essere in presenza. Ciò aiuta tantissimo a vedere e capire le diverse fasi del tuo eccezionale lavoro !! É la liuteria che mi piace di più in assoluto con le linee belle senza interuzioni. The best 👍👍

[@jucamartins1201]

Con ogni video imparo sempre da te. Grazie

[@moneypenny174]

You’re videos always keep me motivated! Thank you for posting them. Would you please tell us the recipe for the casein treatment and what grit sandpaper you’re using.

[@DavideSora]

You can find the recipe for casein preparation at the beginning of this video: kzbin.info/www/bejne/oXrPhX6Qhc2WiNk Find the translation of the text in English in the description window below the video. Regarding the sandpaper, it is not sandpaper at all, but it is Equiseto (commonly called Asprella or horsetail in common Italian jargon). This one: www.kremer-pigmente.com/en/shop/fillers-building-materials/599960-scouring-rush-whole.html It is the stem of a herbaceous plant that was used in ancient times to finely smooth the surface of the wood. What you see is glued onto a piece of masking tape (the blue backing) to keep it flat, but you could also use it as is without this backing. It differs from sandpaper by the arrangement of the cutting edges which are unidirectional and cut rather than abrade the surface as sandpaper does. A modern replacement with a similar edge arrangement and similar grit would be the Micromesh 2400 or 3200, not the same but quite similar as an effect on the wood surface. After the Horsetail (Equisetum) I pass with a horsehair brush (the same one used for bows) which has somewhat the same characteristics, and at the end I pass with common absorbent kitchen paper to polish (the cellulose that makes up the paper has a slightly abrasive effect). Obviously, since it is only the inside of the violin which will not be visible from the outside, you could also use the common 600 grit sandpaper to finish and it wouldn't be a big deal, but you must be careful not to insist too much so as not to remove the very thin layer of casein that lightly covers the wood fibers. I simply prefer to use the systems that were used in ancient times, because they ensure better results with less risk of removing and ruining the thin finish.

[@ViolinVarnishItaly]

Grande lavoro e impegno Davide , complimenti .

[@DavideSora]

Grazie!😊

[@Jeff034]

Thank you so much - just about to glue my back so this is gold!

[@Lancer0047]

Delicate work. thank

[@dasryu3569]

Hi. Is your violin all red? I think it is, but are you using only red varnish?

[@DavideSora]

I always use the same varnish system, which is a "straight and uniform" varnish job, the same as the Stradivari one when his violins were new and came out of his workshop. I don't like varnish that imitates worn ones, that is, I don't make antiqued violins or copies, they give me too much the impression of fake and unnatural. That said, the color of my violins is always quite similar (that's the color I like) but never the same, sometimes lighter and sometimes darker, and with different shades of red-orange. Unfortunately, computer and cellphone screens do not do justice to varnishes, because they tend to emphasize and make colors, especially red, too bright. A paint has transparencies and refractions that do their best when seen in real light and this way they are much more beautiful.😍

[@brahmsbratsche]

I love your videos more than any movie. Question ( i presume the reply is not brief): why do you prefer the gluing of the ribs and back without the mold instead of - i have seen many luthiers doing this one- ribs with mold? The removal of the ribs structure, as you show us in a previous video, doesn’t seem very easy specially when you have the linings in both sides. Thank you

[@DavideSora]

A straightforward answer could be: "since Stradivari and all the ancient Cremonese did this way, why change? It works very well"😊 Clichès aside, even if it might seem so, it is not at all difficult or particularly delicate to remove the form with linings glued on both sides, while on the contrary removing it after gluing the back presents more risks, i.e. when ungluing the blocks from the form with sharp hammer blows, which is a bit traumatizing for the gluing and for the back itself (risk of cracks in the worst cases). Then, gluing the linings on both sides when the ribs are still on the form allows to definitively stabilize the outline, with the advantage of supporting the ribs well and so being able to do all the necessary finishes. If one side is without linings, it will be too flexible and will flex differently under the scraper, moreover an excessive pressure could cause cracks in the ribs. Then the outline is not stable, and will be modified when the linings are glued once the back is glued to the ribs and the form removed, so there will no longer be the perfect correspondence with the tracing on the top plate, made previously without the linings. I prefer to do this tracing with the finished and stable ribs, all linings glued, so as not to have to force during the gluing of the top by pushing and pulling the ribs to make them return to the correct position, creating unwanted tensions that could also have negative acoustic implications. There would be many other details to mention, but as you said, the story would be almost endless...😊

[@SOOAH04]

Another question arises. According to Google search, in the case of Stradivarius copy, it is possible to imitate sound to some extent, but Guarneri copy is almost impossible to imitate sound. Is that true?

[@DavideSora]

No, it is not possible to replicate the sound of any violin. Unless you give to "imitate" a very vague and approximate meaning. In this case, Guarneri or Stradivari makes no difference, it is possible to vaguely and roughly imitate the sound of both.

[@gk1841]

Dear Mr. Sora, I have three questions, could you please help: 1) what is the best glue for the front of the violin (the two front pieces), 2) Violin Glue in general; the rips etc, and 3) what is the best varnish recipe you recommend. Appreciate your help, thank you for all your efforts, have a great time!

[@DavideSora]

The best glue for all violin gluings is hot hide glue. I don't think there is a better varnish, there are many good varnishes around. Usually the best is the one most skillfully applied.

[@EmilianoGirina]

Maestro, mi conceda una domanda. Ho notato che alcuni (pochi) liutai invece di utilizzare un grande numero di piccoli morsetti come fa lei preferiscono utilizzarne pochi (normalmente 6 e autocostruiti) di grandi dimensioni e sagomati come l'esterno dello strumento. In questo modo, dicono, possono incollare tutto (colla animale) in una sola volta. È una questione di preferenze personali o ci sono ragioni che non conosco alla base di queste scelte? Grazie mille in anticipo e complimenti, la seguo con passione.

[@DavideSora]

Preferenze personali e priorità diverse. Io preferisco avere un maggiore controllo della situazione sia per l'allineamento del bordo che sulla temperatura della colla durante l'incollaggio. Questo sistema consente di agire senza fretta e assicurarsi un incollaggio e un posizionamento perfetto. Con il sistema tutto in una volta bisogna essere molto rapidi per evitare di far gelificare la colla prematuramente, e per la fretta il rischio di non poter tenere sotto controllo eventuali scivolamenti delle fasce è alto. Non fa per me.

[@EmilianoGirina]

@@DavideSora Maestro, la ringrazio per la risposta più che esaustiva. Immaginavo che la ragione fosse questa ma essendo ignorante nella sua materia ho preferito chiedere. Grazie mille.

[@smailchalal8793]

Dear master, maybe I missed something but you don't use anymore the positionning pin to align ribs form and back/top plates. And how do you plug this remaining holes. thanks for your response

[@DavideSora]

You get it right, in fact I use the back pins only during construction to quickly and correctly position the back on the ribs whenever I need it, but I don't use them for gluing. The positioning pins are not really necessary for gluing the back, because there should not be any significant deformations in the rib garland. They are however necessary for gluing the top, because the back will have deformed the surface of the ribs once glued, and the pins are used to return the blocks (and so the ribs outline) to the correct place. Since I purfling before closing the soundbox, but I want the back pins to be partially hidden by the purfling for aesthetic reasons, I glue them before starting to cut the purfling channel leaving only the top plate pin holes empty, which are positioned just inside the purfling, to be used when gluing. I close the holes with poplar sticks, making sure that they are smaller than the diameter of the hole, so that, swelling due to the absorption of the glue, they do not press against the walls of the hole, creating a dangerous tension with the risk of causing cracks. PS: If you like to use the pins to glue the back, you should place them well inside the purfling or make all the purfling work with the sound box already closed as Stradivari did.

[@smailchalal8793]

@@DavideSora Thank you very much for these very interesting clarification, but I have a last question on this subject. Poplar is usually white coloured and on the video N°8, I can see those pins blackish, do you treat the polplar to get it black. I think it's only for aesthetic reason.

[@DavideSora]

@@smailchalal8793 No treatment, it becomes dark because the visible part is endgrain, and absorbs more ground and varnish

[@Aecarvalho007]

Maestro I do have a doubt, after treating the inside with the casein sealer, later if you use sandpaper to rub out and expose the wood again, would the sealer not be less effective as compared to leaving the sealer without sanding since it's already quite a thin layer?

[@DavideSora]

Yes, the layer is very thin and you have to be careful not to take it off. In fact, I don't use sandpaper which is too aggressive, but I use Horsetail (Equisetum) which is very very fine and only serves to remove the surface roughness (only the wood fibers that have risen) without affecting the layer in depth. Equisetum in fineness is comparable to a 3200 grit Micromesh sandpaper, very very fine. You must be careful not to apply excessive pressure, and it is also possible not to use the horsetail and rub only with pure cellulose kitchen paper if you are afraid of ruining the layer. However, the dried casein layer is quite hard, so if you are careful, the risk of ruining it is quite low.

[@Aecarvalho007]

@@DavideSora would it be alright though to leave the sealer as is since the wood is pretty close to smooth? Is there any tonal difference in making the wood smoother or is it just for aesthetics?

[@DavideSora]

@@Aecarvalho007 It is probably fine, it is very difficult to know if there will be an influence on the acoustics. The only thing I can imagine is that a surface that is too rough could affect the internal reflections of the sound waves, but it depends on how rough it is and basically they are just guesses that are difficult to quantify. However, this is why I prefer not to leave inside surfaces that are too rough.

[@Aecarvalho007]

@@DavideSora that's a brilliant method maestro, instead the casein sealer could probably be reapplied very lightly one final time so as to cover any exposed wood I guess? Also wanted to ask if it's alright, has shellac been used as an inside sealer? I noticed a 20th century unlabeled violin which seems to have like a coat of shellac inside, and the violin sounds pretty brilliant (almost bright probably because I'm using stranded steel strings) and projecting well

[@DavideSora]

@@Aecarvalho007 Yes, you can reapply a second very light layer, the important thing is to avoid creating a glassy layer that remains too much above the surface, especially in the area of the soundpost where a surface that is too smooth and slippery could accidentally make it move. De-waxed shellac is a sealer widely used in the guitar maker environment, it works well but stiffens the wood less than the proteins, moreover it is never found inside the historical violins. I don't know if this is a problem for you but for me it is😊. In addition, it forms a more slippery surface than proteins, which for the stability of the soundpost is not the best. Of course, you can also leave the bare wood inside, many luthiers believe that this is better, and there is no certainty that the inside of historical instruments was treated in any way, only opinions because the proteins that have been found could simply derive from gluing or subsequent restorations, we will never know for sure and everyone must decide for what they consider most convenient