French Polish or Bust?

Construction and repair of Classical Guitar and related instruments
GEO

French Polish or Bust?

Post by GEO » Mon Feb 05, 2007 2:04 am

Traditional wisdom holds that the best finish for a fine CG is french polish. Now, we're seeing some fine guitars with just the soundboard finished with french polish.

So, my question is: how much a factor in preserving the best sound is french polish over other finishes like lacquer? And is it worth having french polish over more than just the soundboard?

Cheers,

geo

Azalais

Post by Azalais » Mon Feb 05, 2007 4:05 am

The back and sides are made of the densest, stiffest materials possible (rosewood, ebony, etc) It is their very lack of flexibility (and the lack of movement at the rim) that makes them desirable... The soundboard on the other hand needs to be as flexible as possible. French Polish is beautiful and much thinner and more flexible... but is not very durable or bullet proof :(

From a user's standpoint, a stiffer, more durable finish on the back and sides is probably more practical... I suppose each luthier has preferences for how they set up their production... (spray versus french polishing or a combination of the two)... even in the "old days", luthiers often used different finishes... more durable oil varnish on the back and sides, and french polish (or an even lighter finish on bare wood for lutes) Many (like me) don't want to deal with toxic chemicals that require humidity controlled spray booths and serious respirators to apply... I have not yet tried any of the water based polyurethane finishes, but have used all french polish, and combinations of oil varnish and French Polish, or lute wax on bare wood.

French polish, oil varnish and lute wax all have visual and tactile qualities that really can't be imitated... so on a very expensive hand finished instrument, that is obviously a consideration as well... (much of the added cost is because these finishes are time consuming to apply and cure properly (hours, versus weeks)

GEO

Post by GEO » Mon Feb 05, 2007 9:51 pm

Thanks for your in-depth reply, Azalais.

So, judging from what you have said, a light flexible finish such as french polish makes a noticeable difference on the soundboard but it would satisfy just aesthetic factors when used on the sides and back (apart from the environmental issues of using polyurethane and such compounds).

geo

Ramirez 1a Rio

Post by Ramirez 1a Rio » Mon Feb 05, 2007 10:19 pm

I think I'd have to agree on that. So does Bernabe for instance. He does it that way all the way from M30 to M50. Only the Conciertos, Imperials and Especials are french polished on back and sides.

:wink:
Last edited by Ramirez 1a Rio on Wed Feb 14, 2007 4:13 pm, edited 1 time in total.

Sasquatch51

Post by Sasquatch51 » Mon Feb 05, 2007 10:29 pm

For a concert instrument, I prefer French Polish. The exception for me is that Ramirez seems to have (through vast experience) found a way to use varnish that is thin enough not to damp the soundboard.

On an Estudio or Conservatory instrument, I don't think it is as important.

That having been said, I think that there is something to be said for a durable finish on the back, sides and neck and FP on the top.

I know one luthier that uses tung oil on the entire guitar and manages to get a very thin, durable finish with that, but I've never had an opportunity (yet) to audition one of his instruments. He also uses some pretty interesting woods for the backs and sides..such as Australian Sassafras.

Azalais

Post by Azalais » Mon Feb 05, 2007 10:43 pm

I would guess that practicality plays into it too... it depends largely on the size of the atelier and the "other" production guitars that a luthier may be building simultaneously... Someone who is building a small number of very high end instruments may use only FP because it isn't time or cost effective to set up for FP and spraying... If the shop is already equipped to spray, that is a very logical alternative to offer. It cuts production time from weeks down to hours... The top is the easiest part to FP... and it can be done after the backs are sprayed and cured. FP is very labor-intensive and time consuming process (as is oil varnish) in addition to requiring more skill, experience and patience, the curing times between and after each "session" or coat are much longer. Few people are willing to pay for the additional labor, nor are they prepared to maintain the instruments on a recurring basis.

Fingerless

Post by Fingerless » Wed Feb 14, 2007 2:45 pm

Is there a reason any finish is used on the guitar? Does the finish actually improve the sound, or just the look?

I have many wooden items that are not finished in any way, and over time they develop their own patina that is attractive in itself. I don't believe the finish offers much protection, apart from encouraging people to handle the guitar carefully so as not to damage the finish.

So why use a finish at all?

Thanks,
Fingerless

Ramirez 1a Rio

Post by Ramirez 1a Rio » Wed Feb 14, 2007 3:59 pm

With finish the woodgrain of the guitar is much more beautiful. When you drop water on the guitar by accident, it leaves traces without finish immediately. Also dirty oiled Fingerprints would stay eternally.

:roll:

tritone

Post by tritone » Wed Feb 14, 2007 5:00 pm

To answer your question and ask another... my thoughts on a shellac finish is that the top only finish is no less superior than the entire guitar shellac finish. It is a matter of taste, but I will say that all other things constant, the shellac top is better than lacquer top most of the time.

Have you ever finished a guitar with shellac dissolved in alcohol applied with a circular rubbing motion using a cotton wad or ball? Want to share some tips?

My first guitar that I build took me 1 year working part time about 10 hours a week. By the time the guitar was ready for the finish to be applied, I was so exhausted that I decided to use "True Oil". This stuff you can get at FLEET MART (I could be wrong on the name) or where ever they sell riffles. Most riffles are finished with this oil. All I had to do with this stuff was brush it on and wait for it to dry, you can apply as many coats as you dare to go.

The guitar turned out ok, but no way professional and I would not do it again or advise you to use it unless you want to experiment.

My second guitar I used shellac. It did not take me a year this time only half. The finished was too thin just barely acceptable for commercial standards, however I liked the properties of the guitar with this light shellac finish so I'm convince that this is the superior method for top finish.

I'll will have to spend more time on the next finish job that's for sure! I anticipate problems around the fingerboard, soundhole edge, bridge, purfling, you name it!.

Any thoughts, tips or stories you want to share?

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James Lister
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Post by James Lister » Wed Feb 14, 2007 11:11 pm

tritone wrote: Have you ever finished a guitar with shellac dissolved in alcohol applied with a circular rubbing motion using a cotton wad or ball? Want to share some tips?
This is the traditional method of appying shellac, known as french polishing. It is an art in itself, and requires lots of practice and patience. There's an awful lot to it, but I'll just mention a few of my favourite tips:
1) Don't load the rubber with too much shellac - if you press the rubber onto a paper towel, it should leave a mark, but not make the towel really wet. This is the most common mistake when statring out.
2) Leave plenty of time between coats - I recommend only 1 coat per day for "beginners"
3) If things start to go wrong STOP! Wait for the polish to fully dry, rub back to a smooth surface, and start again.

James
James Lister, luthier, Sheffield UK

nuuanupali

French Polish Oui!

Post by nuuanupali » Thu Feb 15, 2007 12:07 am

I had a guitar with the French polish and it always sounded great. However, not more than a few days after I bought it, and got my mitts on it, the top looked a disaster. Nothing you can do about that I suppose. Even a minor nail touch will register in the finish - not to mention sweat from the arm. But really, who cares what a guitar looks like as long as it sings?

Sasquatch51

Post by Sasquatch51 » Thu Feb 15, 2007 4:09 pm

Fingerless wrote:Is there a reason any finish is used on the guitar? Does the finish actually improve the sound, or just the look?

I have many wooden items that are not finished in any way, and over time they develop their own patina that is attractive in itself. I don't believe the finish offers much protection, apart from encouraging people to handle the guitar carefully so as not to damage the finish.

So why use a finish at all?

Thanks,
Fingerless
Actually, many early guitars had unfinished tops. Herman Hauser Sr. frequently left the tops of his guitars unfinished. There is no sonic reason to apply a finish (in fact, the opposite may actually be true), the reasons for it are aesthetic and for protection.

I don't think the type of finish applied to the back and sides matters much at all, but I do think that a very thin finish of French Polish is best for the top from a sonic standpoint, although admittedly it doesn't offer much in the way of protection.

dan711

Post by dan711 » Thu Feb 15, 2007 4:27 pm

Some makers are using a very thin (sprayed on?) layer of nitrocellulos, which is MUCH more durable than French polish. The main things in favor of French polish are (as someone said) its non-toxic, and it gives the wood a very earthy, old school look. It also smells great!
Last edited by dan711 on Thu Feb 15, 2007 4:45 pm, edited 1 time in total.

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James Lister
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Post by James Lister » Thu Feb 15, 2007 4:40 pm

Oil finish is another option. As with shellac, it doesn't offer much protection against nail marks, etc, but it's very easy to repair any small dents. I finish about half of my guitars with shellac, the other half with Danish oil. Interestingly, of all the guitars I've made over the past couple of years, the best ones have all been oil finished. Coincidence?

James
James Lister, luthier, Sheffield UK

jebejava
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Post by jebejava » Thu Feb 15, 2007 5:45 pm

-- Interestingly, of all the guitars I've made over the past couple of years, the best ones have all been oil finished. Coincidence? --


Hmmm.....

I'm going to refinish the top an old guitar soon and was going to do a french polish.

Is there a particular brand of oil finish you would recommend or is it your own recipe?

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