Violin Forum/Message Board

[okawbow]

Finally getting back to work on a fiddle I started 8 years ago. I decided to try and finish making the Fulton's terpene varnish I started about the same time.

About 8 years ago; I pumped air into a clear glass gallon jug of pure gum turpentine. The jug sat outside, bubbling in the summer sun for about 6 weeks. The clear turpentine was reduced down to about 1 quart of thick, dark reddish brown liquid. I put this away in a metal can. The recipe for terpene varnish, calls for the thickened turp to be cooked down to flakes. There are warnings about exothermic reactions, and dangerous flare-ups, as well as trips to the emergency room, if not properly done.

I took 1/2 half of my thick turp and began cooking outside in an iron pan that had vinegar evaporated in it. I didn't get any kind of dangerous reaction. Probably, because my thickened turp had sat for 8 years, and the reactive elements had evaporated. However; something went wrong, and I ended up with black ash, instead of resin flakes.

I heated the other 1/2 of the thick turp to 300c for about 10 minutes, and stopped before it reduced down too much. I reduced heat and added the linseed oil. Brought the mixture back to 300c, and held for about 25 minutes, until the varnish would pull a long string up from a drop placed on a glass plate. I reduced heat, and added small amounts of turpentine, until the varnish seemed thin enough to brush on smoothly. Less turpentine was needed than the recipe called for, because I didn't cook the thickened turp all the way down.

I tried a little of the 8 year old raw, thickened turp mixed with fresh turpentine, on a scrap of wood. It made a nice yellow varnish, and dried in a few hours, to a tough finish. At the same time, I tried some of the cooked oil terpene varnish. It brushed on nicely and left a great looking red brown color. The oil varnish took almost 24 hours to dry. The color left is very distinct and clear. It's the best looking varnish I've ever tried for 1 coat.

I'll get back with pictures in a while, once I get the violin finished. Right now, I'm using the varnish on a muzzle loading flintlock rifle I just completed. The color matches the varnish on the original 1770 era rifle I copied. Gunmakers often used violin varnish on their guns, and the terpene varnish is probably a close match.

[Chet Bishop]

Looking forward to seeing the photos. Congratulations on completing the project.
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Chet Bishop
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[kubasa]

I'd love to see some photos as well. Sounds like it turned out really nice.

[Michael Darnton]

I'd like some pix, too. Like you, I have a very ancient bottle of the thick stuff sitting forgotten in a cabinet. Maybe I could do something with it!

I have heard that you are right about age and the explosive reaction having been lost over time.
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[okawbow]

Here is 2 thin coats on bare spruce. It takes about 24 hours under good conditions for this varnish to dry. I may have a little too much oil in the mix. There is no colorant in this varnish at all. This is the basic terpene varnish made with old, thick, polymerized turpentine that was cooked down at 300C, in an iron pan treated with vinegar, and then cooked with linseed oil at 300C, until it would form a firm "pill", then reduced with turpentine at 230C.

P7280577 by okawbow, on Flickr

[rs]

Nice.
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Randall Shenefelt