Rien secrets, here my system en Anglais:
1 - Quite strong "undrinkable" tea to make the wood darker plus sun light (or UV BOX), 2 or 3 coats;
2 - My oi varnish (Marciana recipe) diluted in turpentine (very thin), 2 coats.
3 - My oil varnish (Marciana) with some pumice and a bit of Terra di Siena Naturale burnished over the wood with a thick rag, leaving no pumice residue over the wood (I take the excess with a rag with some kerosene).
4 - Immediatly after that my oil varnish (Marciana) spread in a thin coat with my fingers (it has a honey like consistency).
5 - If I see that there is too much ground over the wood when it's dry I may remove the excess with allcohol and a rag. I don't want to see a thick coat of ground over the wood, the thinner the better (sometime it will be all inside the wood).
6 - after that 2 coats of Magister's Doratura Rossa heavily coloured with Alizarin and bitumen diluted in Kerosene to brushing consistency.
Here the Marciana recipe in a manuscript in Venice (circa 1550):
book:
"Item Vernice che si distende come olio et seccha presto et è molto lustrante et bella et pare uno specchio di vetro et per stare alla cosa et sopra liuti et simile cose è mirabile;" ma nel testo, queste "simile cose" sono descritte come manufatti in legno, ferro, carta, cuoio e opere dipinte:
"Togli per una misura: una libra d'olio di linseme, et quocilo come si fà in una pignatta invetriata netta, poi vi metti su mesa libbra di pece greca chiara et bella et polverizzata et mesta quando la metti, tanto che si incorpori bene a fuoco dolce, poi vi metti su mezza libra di mastice macinato, et quando lo metti perché ei rigonfia leverai però la pignata da fuoco et mettilo su a poco a poco mestando et incorporando bene, poi torna la pignata al fuoco et mesta tanto che si solva ogni cosa bene, poi mettivi quanto una noce di allume di roccha arso pesto et mesta che si solva et incorpori bene poi lievala dal fuoco et colala per peza lina vecchia et serbala, et per legname, et per ferro et per carta et corame et per ogni dipintura et lavoro farà un opera bellissima et per stare alla aqua, et quando ti pare soda stempera con olio di lino come si fa etc. ".
Claire (who speaks some Italian) offered this translation on MAESTRONET, that I find good (Tradutore, traditore!):
"put a pound of linseed oil in a glass vessel, then half a pound of good greek pitch (clear, attractive, and pulverized). Mix on a gentle (?sweet) heat. Add a half pound of minced mastic. It will swell up so remove the vessel from the fire and mix until every thing is dissolved well. Then add the walnut-size amount of ground burnt alum and mix until it is all incorporated, then filter through a piece of old linen."
Neil Ertz uses it too, and he discussed his methods in this interesting thread:
http://www.maestronet.com/foru...2136&messageid=272165
I pre cook the rosin alone (from Kremer) for about 4 hours in low fire, I do the same with the mastic for about 20 minutes. The resins will get friable, I grind it prior to add it to the hot oil.
Of course making varnish is allways dangerous (you can get severely burned) and should be made outside, etc., etc.