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| Spirit Varnish On Acoustic Guitars http://w-ww.luthiersforum.com/forum/viewtopic.php?f=10101&t=31498 |
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| Author: | Brian Forbes [ Thu Mar 17, 2011 1:33 am ] |
| Post subject: | Spirit Varnish On Acoustic Guitars |
I know a fellow luthier who makes upright basses as well as electric basses with a very unique style to them. He uses a spirit varnish that he believes to be similar to the old violin maker's finishes that he sprays. I'm thinking about trying my hand at the old fashioned spirit varnish with the high tech spraying technique, and was wondering if anyone else out there does a spirit varnish and do they get good results? My friend loves it, and I've seen the work he's done and I agree it's a beautiful finish. I am looking into doing a better finish than tru-oil, and wondering if the spirit varnish is a good investment to get into? Any info would be greatly appreciated. Thank you. |
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| Author: | Michael.N. [ Thu Mar 17, 2011 2:38 am ] |
| Post subject: | Re: Spirit Varnish On Acoustic Guitars |
It doesn't have to be high tech, you can brush it on if you wish. Takes practice to get decent results when using it with a brush. You might find that many of the recipes for spirit varnish result in a finish that is a little on the soft side. I haven't a huge amount of experience with it but at the moment I'm trying a variation of the well known 1704 recipe (I call mine 1705). Most of the recipes call for something that adds flexibilty to the finished film, it can be something like lavender Oil or perhaps the addition of a little drying oil. The 'trick' for using it on a Guitar is to find a recipe that results in a finish that is reasonably hard and durable but without becoming brittle and chippy. |
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| Author: | Laurent Brondel [ Thu Mar 17, 2011 5:39 am ] |
| Post subject: | Re: Spirit Varnish On Acoustic Guitars |
Spirit varnish is shellac with added oils and resins, and depending on the mix it can be all over the place in terms of hardness and elasticity. Most can be French polished. Even for bowed instruments it's a relatively recent finish (19th century), before that oil varnish was the standard. In any case it is not going to be much harder than shellac. It also takes longer to cure. Behlen has a ready made spirit varnish called "Violin varnish", it's an excellent product. As long as the finish is thin it is fine, too thick and it remains soft forever. |
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| Author: | ernie [ Thu Mar 17, 2011 9:06 am ] |
| Post subject: | Re: Spirit Varnish On Acoustic Guitars |
I concur, I just used a violin spirit varnish from germany (gewa) that was thinned down with alcohol, to make it flow and brush out better . I used a squirrel hair 1 in violin brush (germany) still got stray hairs. Waited 3 weeks and buffed with 800 grit paper , pumice and rotten stone. It gave the uke a warm soft natural glow. I don/t always care for the plastic embalmed look . If it was thinned down more, it could be sprayed with a touch up gun. But with 3 coats, felt it was not necessary.. Hidersine (england ) makes a spirit varnish. There is a co. kremer pigments in NYC that sells supplies , brushes , resins, etc to artists and makers . There are several companys on internet selling supplies. |
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| Author: | Michael.N. [ Thu Mar 17, 2011 9:53 am ] |
| Post subject: | Re: Spirit Varnish On Acoustic Guitars |
It seems that the Behlens is pretty similar to the 1704. Probably has a limited shelf life like many shellac based finishes. Ernie. You did 3 brushed coats and that was it? I'm using a cattle hair brush that works fairly well. I've tried one of the synthetic Golden Taklons and found it hopeless. It was an extremely well made brush but I found myself having to recharge the brush far too frequently. Some people swear by them and won't use anything else. Many years ago I had a pure squirrel. Beautifully soft hair but I found that I lacked control because of the hair length. Shorter and I feel it would have been much better. Going by the images of Squirrel haired brushes on the net the hair seems much shorter than the one that I had. |
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| Author: | Brian Forbes [ Thu Mar 17, 2011 12:09 pm ] |
| Post subject: | Re: Spirit Varnish On Acoustic Guitars |
I believe the luthier I was talking to uses something in the mixture (it looks like small white sap balls from a tree) that helps it be flexible and actually dry out over time. I don't know exactly what it's called but the tweo bottles he showed me were fiiiled with shellac flakes for one, and these little white globs in the other. I am not at all interested in a finish that does not dry completely, but I really like the look of violin finishes, and I like that I can blend shellac flakes to get a certain hue if I want something lighter or darker. I'm also really leaning towards spraying because of the perception I have that it will be a little easier to get a better and more even finish that way. I already to a rub on finish, I want to try and make the leap into spraying, but I dont want to spray Nitro really. I don't like how some guitars look like thy were dipped in plastic and allowed to dry. I want a finish that is going to have the least effect on the tone of the wood as possible, and I would think that a thick plastic casing around the entire instrument would restrict the vibration of the plates. |
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| Author: | Michael.N. [ Thu Mar 17, 2011 12:18 pm ] |
| Post subject: | Re: Spirit Varnish On Acoustic Guitars |
Just a guess but I think your white sap balls sound like Gum Mastic. Expensive stuff, although you don't need a lot in the mix. |
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| Author: | WaddyThomson [ Thu Mar 17, 2011 2:00 pm ] |
| Post subject: | Re: Spirit Varnish On Acoustic Guitars |
Just a point about spraying shellac. It will not get as hard as a French polish finish. The rubbing causes the shellac, over time, to harden into an amalgamated finish, more than when it is sprayed. When it has aged (years), it's about as hard as lacquer, and is more repairable. However in the early years it is more fragile. |
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| Author: | Michael.N. [ Thu Mar 17, 2011 2:14 pm ] |
| Post subject: | Re: Spirit Varnish On Acoustic Guitars |
I've heard that as well Waddy. It seems to go against my limited logic. Shellac is shellac and I fail to see how applying the stuff with a rag results in a harder film. Perhaps it just seems harder, possibly because it has been applied thinner. |
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| Author: | johnparchem [ Thu Mar 17, 2011 2:52 pm ] |
| Post subject: | Re: Spirit Varnish On Acoustic Guitars |
Michael.N. wrote: I've heard that as well Waddy. It seems to go against my limited logic. Shellac is shellac and I fail to see how applying the stuff with a rag results in a harder film. Perhaps it just seems harder, possibly because it has been applied thinner. French Polish is not just applying the stuff with a rag. There is a tremendous amount of energy that is applied to the finish while polishing or burnishing the finish. That energy results in a different a different finish than spraying layers of shellac on to the guitar. |
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| Author: | Michael.N. [ Thu Mar 17, 2011 3:28 pm ] |
| Post subject: | Re: Spirit Varnish On Acoustic Guitars |
Yes I'm sure it results in a different optical effect, however slight that may be. What I'm trying to understand is how it makes the film harder. In other words how does applying pressure/circles create a harder finished film? |
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| Author: | alan stassforth [ Thu Mar 17, 2011 3:49 pm ] |
| Post subject: | Re: Spirit Varnish On Acoustic Guitars |
http://www.archive.org/search.php?query ... nishing%22 found this informative read this morning. Learned something. Read the first book on the list. 58 pages. |
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| Author: | johnparchem [ Thu Mar 17, 2011 5:16 pm ] |
| Post subject: | Re: Spirit Varnish On Acoustic Guitars |
Michael.N. wrote: Yes I'm sure it results in a different optical effect, however slight that may be. What I'm trying to understand is how it makes the film harder. In other words how does applying pressure/circles create a harder finished film? Shellac is a plastic material, it is not hard to understand that the combination of the solvent and pressure can combine and compress the material. For a given thickness of finish you have more shellac, a higher density, in a French polished surface. Think shoveling asphalt on a road without rolling vs. with rolling. |
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| Author: | Laurent Brondel [ Thu Mar 17, 2011 5:34 pm ] |
| Post subject: | Re: Spirit Varnish On Acoustic Guitars |
Oy ve… Shellac is an evaporative finish, no matter how it is applied the solvent (DA) will gas out eventually and the remaining resin will be the same (i.e. shellac flakes). It is true that spraying shellac results in a finish that is softer in the short term. My understanding of this is that in spraying coat after coat the solvent does not completely evaporate and the film contains more moisture, whereas French polishing moves things around and successive coats are extremely thin. The sprayed (or brushed) shellac will remain soft for a few months, perhaps a year, and will eventually harden and be the same as the French polished version of it. Using a faster solvent (acetone mixed with DA, definitely fresh DA) may go some way in solving the issue with spraying. |
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| Author: | ernie [ Thu Mar 17, 2011 7:58 pm ] |
| Post subject: | Re: Spirit Varnish On Acoustic Guitars |
To michael k in the uk. I brushed on a coat of shellac before applying the violin varnish. The varnish had thickened over time, and was thinned with more( spirit) or alcohol. I think I added some castor oil to make it flow better . I varnished a small tenor ukulele. and did not want to put in huge amounts of time. The bridge( walnut) split today, and am now replacing it with a sturdier one of osage orange , similiar density to indian rosewood , but yellow in colour. |
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| Author: | WaddyThomson [ Fri Mar 18, 2011 10:04 am ] |
| Post subject: | Re: Spirit Varnish On Acoustic Guitars |
IMO, the difference between French polished shellac and sprayed shellac, is that FP shellac becomes an amalgamated finish, while sprayed shellac, is coats. Yes the successive coats bite into the previous coats, but it's the rubbing process that amalgamates the finish. What you end up with when spraying is a thicker build of less density, as so cleverly described in the asphalt description. Certainly it will become harder over time, but I don't believe it'll ever be as hard as a FP shellac finish. I also think that over time, it may be more subject to crazing, depending on how well the coats blend together. |
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| Author: | Michael.N. [ Fri Mar 18, 2011 10:28 am ] |
| Post subject: | Re: Spirit Varnish On Acoustic Guitars |
I'm not sure about the Asphalt analogy. I think I will have to do some scratch tests and do a direct comparison between brushed and a french polished finish. If you try scratch a flake or a piece of Button Lac it seems pretty hard. I don't believe they are subject to any pressure in the process. Then again they haven't been dissolved in a solvent either. The Spirit Varnish may be more susceptible to crazing but that really would depend on the particular recipe. I have several late 19 th century German trade Violins. One shows crazing and chipped areas, with the varnish darkening to almost Black. I have another that shows absolutely no signs of it and it seems no softer than your average french polished surface. It has a few very small chipped areas to the Back but considering it's 120 years old that's hardly surprising. |
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| Author: | Laurent Brondel [ Fri Mar 18, 2011 11:49 am ] |
| Post subject: | Re: Spirit Varnish On Acoustic Guitars |
Waddy, with all due respect the asphalt analogy doesn't hold water. Amalgamation or not, the solvent will eventually escape from the finish. The fact is that sanding through layers of sprayed shellac or lacquer one does not see any witness lines, so the finish is pretty well amalgamated… Michael, I think the process of preparing (and eventually de-waxing) shellac flakes involves the raw product to be dissolved more than once and left to dry in sheets that are then broken into flakes. As a side note, I restored a 1928 0-18K a few years ago that was entirely finished with shellac. I do not believe Martin FP the guitars, most likely the finish was sprayed. It was relatively thin, but too thick to have been FP'd. That finish was pretty tough, and in very good condition considering age and (ab)use. Still dissolved with DA though. |
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| Author: | WaddyThomson [ Fri Mar 18, 2011 8:27 pm ] |
| Post subject: | Re: Spirit Varnish On Acoustic Guitars |
I can't argue my point any better. I only know that both Milburn and Michael Payne both feel that it is the pressure of rubbing that amalgamates the finish. |
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| Author: | CWLiu [ Sat Mar 19, 2011 2:31 am ] |
| Post subject: | Re: Spirit Varnish On Acoustic Guitars |
I've read somewhere that shellac with different solvents cure differently. IIRC, the film of ethanol-shellac is more porous than the film of isopropanol-shellac. If that was true, I suppose french polished shellac could be less porous than sprayed. |
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| Author: | Michael.N. [ Sat Mar 19, 2011 4:14 am ] |
| Post subject: | Re: Spirit Varnish On Acoustic Guitars |
Yes. IF it is true. People say many things. Unless there is irrefutable scientific evidence it's probably best to do the experiments yourself and reach your own conclusions. I'm old enough to remember Guitar makers telling everyone that Hide Glue was weak and that glues such as PVA were better for instrument building. Some of these makers weren't exactly unknowns either. |
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