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View Full Version : which guitar varnish?


Armando
04-29-2004, 08:37 AM
Hello

I have recently finished my first selfmade flamenca blanca. Now it comes to the varnishing. The more books i read about that topic, the more uncertain i get about which varnish gives the best results.
Some Luthiers swear on french polishing and others consider french polish as inaproppriate for classical or flamenco guitars. They argue, that french polishing is not beeing used by violin makers because it changes the tonal qualities of the violin in a negative way. I'm aware, that a guitar varnish must be harder than a violin varnish as it must be more resistent against exposure.
The alternate solution is to use an oil based varnish. They are known to be usually very slow drying. I have no experience with either of them. I don't have the opportunity to compare guitars with both kind of finishes.

I would be glad to receive some oppinions about it.

Thanks

NGiorgio
04-29-2004, 09:05 AM
Armando,

First, let me say that I am not an expert on guitar finishes but I will be happy to comment on some of the finishes which I have experience with on my own guitars.

I currently own guitars with nitrocellulose lacquer, oil based varnish and one with a french polished top and lightly lacquered back and sides. The advantage of lacquer and oil based varnish is long term durability and appearance. The french polish finish is most likely going to allow for the top to vibrate better and produce a nicer quality of tone but will not be very durable. I find that my guitar with the french polished top (which is a blanca) seems to have a richer, fuller and more pure sound, compared to the others. I would think that a completely french polished guitar is the best way to go for overall tonal quality but with the tradeoff of long term durabilty and appearance.

I have recently seen guitars by luthiers Manuel Velazquez and Robert Desmond who are using oil based varnish for back and sides and french polish for the tops.

There are many ways to go with the finish of a guitar. You have to find which will work the best for you. Probably with a lot of trial and error.

Congratulations on the completion of your first guitar and good luck with the finishing of the instrument.

Faya
04-29-2004, 05:39 PM
Must be nice to be able to make your own guitars. :)

I like the sound of French polish, but wish it was as durable as laquer.


Later.

compagnito
04-29-2004, 11:33 PM
I don't know for sure but wouldn't French Polish be easier for an amateur to apply (assuming you are an amateur - otherwise apologies).

Apply lacquer might be run prone - difficult to perfect - dunno?

keith
04-30-2004, 02:45 AM
i would contact a luthier in your area for advice. although french polish may appear to be easier, from what i have heard from folks who do it, and through books, it is damn difficult--it is an art that requires a long training period. get expert advice or maybe have a luthier do it for you or work with you. you could always have the top french polish and everything else lacquer.

now, i am going to give you an idea that may, well, knock your socks off. go to the home depot (or the swiss equivalent of a massively large hardware store), get a couple of cans of florescent orange paint, spray paint your guitar. whoala! you now have a glow in the dark conde hermanos paint job. :wink:

jens
04-30-2004, 02:52 AM
I think, if you want to get an authentic flameco sound out of your new built guitar (by the way: congratulations, I wish I had the mechanical skills, to make a guitar myself), French polishing with shellac will be the only alternative for you. And don't mind what some violin makers may say: French polish is absolutely appropriate for finishing guitars. In the violin making tradition oil varnishes only established themselves, as the baroque Italian school of violin makers with its prominent exponents Stradivarius and Guarneri chose this kind of varnish to give their instruments the tonal characteristics they had in mind. And as you may know violin makers already deify those baroque Italian builders and most of them try to copy their idols as exactly as possible.
Every kind of varnish will influence the sound of an instrument. The French polishing technique was first employed by instrument makers from northern countries like Germany or France where the sun light because of certain atmospherical features does not contain much ultraviolet radiation that is needed to harden oil varnishes. They decided to choose fast drying varnishes based on alcohol mixed with shellac. And that is what has since then also been used on classical and flamenco guitars. French polish is definitely not a very durable varnish, but it will make your guitar sound very good. Furthermore it is rather easy to repair. So as you are capable of doing this yourself, French polish would from my point of view be the best choice. I would use it at least for finishing the top. If you want the rest of your guitar to be more durable, you can use a synthetic acrylic finsh or nitrocellulose lacquer for the back and sides. But be aware of the fact, that those synthetic finishes will be a pain to repair, if at some time there will nevertheless occur a damaged area in the lacquer.

Armando
04-30-2004, 10:10 PM
Thanks everybody for the opinions and comments.

Yes, i'm an amateur builder. With only one guitar i cannot be a professional. Neverthless my intention is to professionalize my skills as much as possible.
I will not be satisfied with my guitars until i have built a guitar that can be compared with those with a big name.

I think i will use shellac for my first guitar. I know, that the technique is quite difficult for a beginner, but i will get advice from an experienced luthier in my area.

I think that there is no other way for me to learn, than to learn be try and error. This may be costly and timeconsuming but i consider it as the best way to learn.

I will tell you the result, when the french polishing job is done.

Regards

Armando

Crazy_Horse
05-03-2004, 09:19 AM
It's a myth that French Polishing is like some dark art that only a select few can learn. I started learning about 4 years ago by buying Ron Fernandez's video "French Polising for Guitar Makers" then searching for every other source of information I could find. A good one is on http://www.milburnguitars.com. I use all the materials described in the video, but I find pulling straight across the wood with the grain gives a smoother finish without the swirls that come from rubbing in a circular fashion. If you're analytical, good with your hands, willing to invest the time and money in the materials, and willing to practice, one can become a fine French Polisher in a short time. I wouldn't recommend starting out on a good guitar, however. I reglazed the top of my Velazquez with fantastic results -- much better than the original finish. The tone will soften for a few months while the shellac cures, but once it's totally hard (about a year) the tone is unchanged.

jholcomb241
05-11-2004, 05:59 AM
I am sure by now that you have finished your guitar and learned something about French Polishing. I believe finishing is a evolving art and you must go through trial and error to find what works best for you and what results in the most pleasing sound. I am a novice and still learning. I have French polished 4 classical guitars and to my ears I prefer the sound of my french polish guitars to a lacquered top guitar that was made for me by a world renowned builder. I have also experimented with lacquering the back and sides and just French Polishing the top. I like the result. Why would I do that? Time mostly and it fairly easy to get that deep glassy look with lacquer. It also does not have a noticeable affect on the sound- to my ear anyway. With French polish it takes many hours of hand work and patience. I believe in the final analysis the sound, playability and durability of an instrument is the result of wood selection, construction technique, experience and how you apply the finish. Lightly applied lacquer can rival French Polish. I like doing French polish because it is non toxic, easily repaired and beautiful. One other note. I French polish the necks because I can later reshape a neck and refinish it very quickly. There are no short cuts or majic tricks. Also, on the subject of durability, I think most serious classical players treat their expensive instruments with care and thus they don't need to be built like a Dreadnought going to battle.

NGiorgio
05-11-2004, 06:37 AM
How does the french polished neck hold up to the perspiration and oils etc. of the hand? Is it almost as durable as lacquer because you can apply more polish than to a top?

stevec
05-11-2004, 09:45 AM
Jack,

All very helpful info. Could you elaborate on "Lightly applied lacquer can rival French Polish". When you say "Lightly", do you mean just enough to seal the wood or just enough to seal pores. I think I would prefer this just for the durability. I think the best combo might be Lacquerd, back, sides, and neck, with French top.

Stevec

Pepe Vergara
05-11-2004, 11:46 AM
The theory of French polish is easy to learn, but difficult to apply. For the first guitar, I advise you go with Tru-oil (Kmart, gun section for $4). My first guitar was done with Tru-oil few years ago (it looks better and better every day). You cannot go wrong with Tru-oil (it is a varnish that uses linseed oil and other catalizers). You just apply and wipe it off, apply it and wipe it off, etc. If you care for your health, you can stay away from nitrocellulose. Although, I have finished some guitar's back and sides with nitro. Some clients prefer it like that. I always use Fpolish for the top (except my first guitar, which has tru-oil). Tru-oil does not affect negatively the tone of the gutiar. Nitro does if applied to the top, and in lesser scale if applied to the back especially of light wood guitars. Flamencos are light.

jrethorst
12-10-2004, 06:27 PM
I found the following on usenet. It may have been from Al Carruth:

Martin Schleske, who has a PhD in physics AND a master's rating in the German violin making guild, published some results of experiments he did with different finishes several years ago in the Catgut Society 'Journal'. Some of the more interesting things he found were:
1) Plain drying oils have _very_ high damping factors, and really soak into the wood, so they can add a lot of weight. All of this gets you no particular protection. I don't think he tried any polymerized oils.
2)Oil-based varnishes are much better than drying oils, and can give good protection in thin layers.
3) Shellac adds a fair amount of stiffness across the grain. Shellaced wood strip samples had lower damping than bare ones.
4) Nitrocellulose lacquer is about 1/3 harder than shellac, and has about 1/3 less damping.

In theory nitro would be a better finish than shellac, if it only stayed put. It breaks down over time, which is why old lacquer turns orange and crazes. You'd also have to apply it hinner than FP to get the benefit, which would be hard to do. I suppose you _could_ FP with it, but I'm not going to sit in a room full of lacquer fumes and pad the stuff: I like my liver too much.

Many people who do use lacquer say it should sit and outgas for a month before it's realy cured. Alcohol is less volatile than lacquer thinners, and takes longer to go away. Still, a two week wait is a big help, and a month is even better.

jjjaallen
12-11-2004, 07:38 PM
Pepe is right - Tru-Oil is the ticket. You won't get the 'plastic' nitro look, but the wood grain will be much enhanced (make sure that your surface prep is flawless and polish the wood to at least 600 grit). Besides, when all is said and done (20 + coats) it will be at least 10 time thinner than nitro. Also, neck action is much better because your thumb will not stick as in a 'plastic' surface finish. This stuff is a no brainer for a first guitar finnish. Highly recommended.

schrammguitars
12-21-2004, 07:56 AM
With FP thinner is better. Thick FP is soft. The thinner it is the more durable it will be.

daniel711
12-21-2004, 11:47 AM
I've been reading this thread with much interest, and since there are some very interesting opinions, I have a few questions... What exactly is nitrocellulose? My Australian-made guitar has a sprayed-on nitrocellulose finnish, and I was under the impression that this was less toxic (to the finisher) than laquer? Is it? The back and sides of this guitar are high gloss and very durable, while the top is a very thin layer satin finish. All in all, a very beautfiul looking instrument. What is the difference between nitrocellulose and laquer, chemically and practically?

C. Vega
12-21-2004, 12:00 PM
Nitrocellulose is a type of lacquer, very toxic and very flammable. Not particularly pleasant stuff to work with. Proper equipment and safety precautions are a must.
Many of the so-called "lacquer' finishes on guitars these days are actually polyester or a catalyzed urethane though "nitro" is still pretty common.
You don't want to be snorting the fumes from any of them.

Pepe Vergara
12-21-2004, 01:23 PM
French polish uses:
1) shellac (a natural resin) the wax extracted from the natural shellac mixture is used to cover the M&M candies
2) Oil: You can use olive oil
3) Alchohol: If you use pure Ethanol (97% proof) is better.

It will smell good around you, you may get high with the vapors and even get a zip of booz. French polish becomes then a very pleaseant experience.

If you inhale nitro vapors, you may be dead or with a very nice cancer before you get the age of retirement.

jetiii
12-21-2004, 05:33 PM
Pepe isn't crazy here about the M&M's. About 30 years ago I was looking for French Varnish in LA. A manufacturer gave me a sample dissolved in ethyl alcohol. It was lableled "Food Glaze". I was told M&Ms was one use but thought it was the varnish and not the wax. Other uses were medical pills and they were trying to get it used on apples to preserve them. Shellac has many industrial uses. Not bad for a bug juice and, after all, it is organic.

jjjaallen
12-21-2004, 06:28 PM
http://antiquerestorers.com/Articles/jeff/shellac.htm http://heritage.dupont.com/floater/fl_nitrocellulose/floater.shtml

jja

Pepe Vergara
12-21-2004, 07:52 PM
I was told M&Ms was one use but thought it was the varnish and not the wax.

I may be wrong though!! It's being a long time since I learned that.

fmorelli
02-23-2005, 09:43 PM
I've not gotten around to following Jeremy's instructions but have read them several times .... certainly a well done and worthy reference:

http://www.classicalandflamencoguitars.com/FrenchPolish.htm

Cheers,

Filippo