DonLeister

Happy New Year Everyone! Cheers to old friends and new!

Mike, I might not say ‘cold’ but precooked to the point that it is more of a pigment than a resin. Although it doesn’t behave like a pigment because it will fully dissolve in hot varnish or hot rosin or acetone. I dunno what you would call it in a technical sense

The 1711 Stradivari 2 weeks ago.

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Jim I think your sample looks good. Of course what goes under it will make a difference like you say. From reading Hargrave's recipe for making varnish I was always left with the impression that his long slow resin cook is the resin component of the whole varnish. In other words he is not adding the darkened resin to an already made varnish. I just now realized that he was adding this dark resin to the already made 'boring' varnish that he described earlier. And that is how Joe taught us.

Jim, thanks. We are doing the same thing pretty much then. The only difference is I add my dark rosin in powder form directly into the first cook, (sprinkle it in slowly) instead of blending it with oil first. it dissolves completely into the varnish. It can make a very dark and thick varnish so it needs some oil added at the end of the cook. I tried mulling the dark powdered rosin in oil like Joe's but mine wouldn't dissolve into the varnish cook. I mulled it in raw oil and left it for a day (sealed) and it basically dried like rubber almost. I think I might try your way of melting oil into the dark rosin at the end of it's cook. Is that how you did it? While the dark rosin is still hot? I know after I have cooked the rosin down to darken it, I can't get it out of the pot before it hardens mostly so I scrape it out after it cools. It's very brittle. It looks like it is burnt but it will completely dissolve in acetone or hot varnish.

Thanks Jim. Just to be sure of your process, you melt the darkened rosin with oil at 200c then add that to the first cook of rosin and oil (which is not nearly as dark). And the first cook is hot when you add the dark rosin oil cook? If I have that right, when your final varnish cools and is too thick, you then thin it with raw oil?

If I understand correctly you cook a varnish , 50:45:5 , which is not very dark. Mastic added at the end of the cook at a lower heat than the rosin/ oil cook. To that you make 50:50 raw oil and very well cooked rosin ( mulled together ?). That basically looks like black paint right? Then you add that 2 parts to 1 part previously cooked varnish. And it is added under heat at 100c., right ?

Jim, what is the ratio of oil to resin? And is that all the varnish ingredients?

I agree with you about taking note of the inflection point on the arching. I see it as a helpful way to define or reproduce the overall arching scheme.

If I understand your drawing correctly, the arc going from the lower bout to the upper bout is the inflection point, right? I have observed and mapped the inflection points on some good instruments and they are not similar to your drawing at all. I have to ask, have you mapped the inflection points on good instruments and seen anything like what your plan shows?

I would disagree. Using electric (or flame, but I wouldn't) thin metal will have some very hot spots and thicker metal will be considerably more even.

I have been using it as a ground, one coat, really thin, it is indestructible. Make a paste with fumed silica, rub it on, wipe it off well until nothing shows on a rag, rub it with chalk, rub that off well and the instrument will look burnished almost and is practically dry at that point. It does need UV to cure though. The instrument will be sealed 100%, then you can put other really dark varnishes on. The sealing effect will happen with other oil varnishes too, it is the technique, rather that that particular varnish.

An asparagus pot works well, I use this one;

Put the fiddle in a box with a tray of ammonia and fume it for some hours or days.