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actonern Super Member
Joined: 15 Aug 2007 Posts: 444
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Posted: Tue Oct 02, 2007 4:35 pm Post subject: Henry Strobel Varnish |
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In his "cello making" book Strobel sets out a recipe for varnish, which is 1 part cooked down colophony and 2.5 parts unprocessed walnut oil. Color is achieved in the resin by adding rusty nails while cooking it down (about 8 hours) prior to incorporating the oil and cooking some more.
I did up a batch recently and while the color is a lovely reddish brown, I find that a coat fades visibly when set in the sun to dry. Does anyone with experience with this type of iron colour based varnish know if the color will eventually reach a point of maximum fade... that is to say it will fade some and then no more?
I have until next spring to continue experimenting, but it seems otherwise like an excellent varnish. I just wonder how much additional pigment/colorant I need to "over-add" to end up with a lasting result.
Best regards |
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MANFIO Super Member
Joined: 11 Apr 2007 Posts: 458 Location: Sao Paulo
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Posted: Tue Oct 02, 2007 7:42 pm Post subject: |
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Hi! I've just cook some 2 parts linseed oil, 1 part colophony (dark, from Kremer) and one part mastic. Thanks God no fire ignition!!!.
I'm using Kremer's alizarin in oil from SINOPIA:
236107 Alizarine Crimson dark in linseed oil
I use some alphalt also (roof tar) dissolved in Kerosene, together with the above mentioned alizarin in a strong solution to colour my oil varnish. Kerosene makes brusing easier. _________________ www.manfio.com
http://www.flickr.com/photos/7875988@N02/with/464604020/ |
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actonern Super Member
Joined: 15 Aug 2007 Posts: 444
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Posted: Wed Oct 03, 2007 7:17 am Post subject: |
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Manfio:
Your varnish is so successfully applied! Can you tell us how you apply such intensity of colour without streaking? |
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MANFIO Super Member
Joined: 11 Apr 2007 Posts: 458 Location: Sao Paulo
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Posted: Wed Oct 03, 2007 7:39 am Post subject: |
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Hi! Kerosene makes brushing easier. This is my varnishing process (ok, I'll change somethings every time...):
I start with a somewhat dark coloured wood, this way:
Sun tanning,
strong tea,
4% potassium nitrite in water followed by exposition to direct sun (6 hours), perhaps 2 times that (test in samples first, take care with the top, it can get blotched),
some of my oil varnish (the recipe in Biblioteca Marciana, Venezia, also on Baese's book: 2 parts oil, one part colophony, one part mastic) diluted in turpentine, 2 coats,
strong tea,
light glue sizing with a bit of alum,
stain (harmell)
more tea,
light fumigation with amonia.
If it gets too dark in the middle of the above mentioned process, stop it. It's a bit intuitive, like cooking (I love cooking...).
After all that the wood will have a strong cinamon colour and the wavings will be darker. This method would not be used by people with a faultless and very clean work, but it's good for a "Guarneriesque" work as mine.
Ground: my oil varnish (2 parts oil, one part colphony, one part mastic) in a paste with fine white tripoli (or fine pumice) rubbed into the wood (don't leave it build up, don't leave it thick anyway). I take off the excess with a rag with kerosene, apply a bit more of my oil varnish and rub it over the wood with my fingers to develop a very thin, but quite reflexive surface. This ground will penetrate a bit in the wood and that will make the contrast in the flames more visible, I think. The penetration in the wood will be stoped in different depths of the wood (this process had already started with the aplication of my thinned oil varnish) causing the holografic and tridimensional effect.
Varnish:
one coat of Padding's "Doratura Cremonese" (or "Doratura Rossa") thinned with Kerosene and heavily coloured with asphalt (roof tar) and Kremer's Alizarin Crimson in oil. The kerosene/pigments thinner will be very very concentrated, a residue will form in the bottom of the jar, so filter it;
two coats of Padding's "Doraratura Rossa" used the same way. Used 1500 Micro Mesh betwen the coats, as well as tripoli. Polished with tripoli and polish. _________________ www.manfio.com
http://www.flickr.com/photos/7875988@N02/with/464604020/ |
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actonern Super Member
Joined: 15 Aug 2007 Posts: 444
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Posted: Wed Oct 03, 2007 8:11 am Post subject: |
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"one coat of Padding's "Doratura Cremonese" (or "Doratura Rossa") thinned with Kerosene and heavily coloured with asphalt (roof tar) and Kremer's Alizarin Crimson in oil."
Thanks, Manfio! But how do you apply these coloured coats? Do you use your fingers? Do you stipple it on with a hard brush and then feather it out with a soft brush? It is so even. |
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MANFIO Super Member
Joined: 11 Apr 2007 Posts: 458 Location: Sao Paulo
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Posted: Wed Oct 03, 2007 9:25 am Post subject: |
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Hi! I apply the DORATURA ROSSA and CREMONESE with a soft brush, I dilute them with kerosene to brushing consistency and apply with the brush.... I find applying it with my fingers too time consuming and irritating...
The darkened wood helps avoiding streaks, but with the kerosene you will be able to "paint" your varnish, you will have time to correct faults. Try on samples first.
I use 5 grams of Padding's varnish for each coat on these large violas, but perhaps 4 grams will be suffient for a violin. _________________ www.manfio.com
http://www.flickr.com/photos/7875988@N02/with/464604020/ |
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actonern Super Member
Joined: 15 Aug 2007 Posts: 444
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Posted: Wed Oct 03, 2007 12:16 pm Post subject: |
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Marvellous results... thanks for sharing so freely. |
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Andres Sender Super Member
Joined: 23 Mar 2007 Posts: 275 Location: N. CA
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Posted: Wed Oct 03, 2007 1:21 pm Post subject: |
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Actonern–that recipe is based on a recipe provided to Mr. Strobel by the late Robert Lundberg. I made some of the varnish at Robert Lundberg’s shop one warm summer day. Mine did not end up with a strong red color, and although I did not notice any fading in the sun, I have noticed the varnish darkening over the approximately 10 years I’ve watched the samples.
You should call Henry Strobel and ask him about it, I’m sure he’d be glad to tell you his experiences. |
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actonern Super Member
Joined: 15 Aug 2007 Posts: 444
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Posted: Wed Oct 03, 2007 1:28 pm Post subject: |
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Andres:
With the benefit of 10 years of observation, can you comment on the quality of the varnish? |
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Andres Sender Super Member
Joined: 23 Mar 2007 Posts: 275 Location: N. CA
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Posted: Wed Oct 03, 2007 3:29 pm Post subject: |
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Actonern– It seems fine so far, durable but flexible, and the color relates well to what I see as the ‘base color’ of historical varnishes (although it seems to be getting rather dark unless the process is nearing its end). Transparency’s fine. I can’t tell you how it works with added colors though.
I don’t currently imagine that I will ever use it on an instrument, for various reasons. The reason specific to this recipe is that due to comments in the literature and from experienced violin makers, I am mistrustful of the iron content and rosin-based varnishes in general. It might be fine, but I veer away due to a slight preference toward using something that doesn’t have two strikes against it, even though they’re all pretty much hearsay. |
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