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A number of builders that I know think that they can hear the difference in some instances that the finish on a guitar makes. I believe that I can too.

Ervin Somogyi mentions in his new DVD that he believes that a steel string with a french polished top is the best solution for sonic performance.

Classical guitars have been finished with french polish probably most of the time and for all of the time that they have been around.

So what do you think? Can you discern the difference that a guitar with too much finish on it may make? Do you think that a french polished top is sonically superior to any of the other commonly used guitar finishes?

My own thinking is that I believe that a guitar with a tough finish i.e. poly, urethane, nitro on the back and sides with a FPed top may be the best of all worlds provided that... the end user for this specific guitar does not use a windmill style and a pick.....

So what say you - what are your thoughts on if the finish on a guitar matters from a sonic view point? And... if you agree with me that the finish may matter why do you suppose that is?

Thanks

Oh and I almost forgot - if you have any thoughts about oil finishes on guitars this might be a good place to discuss.

Thanks!

No doubt that finish with lesser elasticity per equal thickness or greater solids weight per thickness have a greater dampening affect. it has always (since I have been building anyway) been the common community belief that FP was the least dampening finish generally speaking. This all subject to so many variables like thickness. That said a hard rule is fleeting. However comparing apples to apples I agree

This is one of those areas in which the conventional wisdom makes me go "hmmmmmmmmmmm." I don't pretend to know the answer, but I've never been persuaded by the old logic.

But here's what I think.

For most builders, A THICK finish would be .01". A THIN finish is probably around .005". Maybe a little less if you FP. Certainly, that extra .005" of finish has some weight, and it also has some stiffness. But how much? Maybe one of the engineers on the forum can tell us. I don't personally know. My gut tells me that it's not very much, especially with a soundboard roughly .125" thick, and a boatload of braces in addition to that. I suspect that an extra .005" of finish has an extremely marginal impact on overal weight and stiffness.

The impact may be so marginal that it is less than the margin of error introduced in other parts of the building process. For example, you voice your top BEFORE you scrape and sand the bindings (and the area of the top adjacent to the bindings), sand the top to prep for finish, and do various other tasks that remove material from the top, right? Well, assuming you voiced your guitar PERFECTLY during the voicing phase, then you remove material when you sand the binding/purfling area, then remove more material when you prep for finish, you have now made the top lighter and more flexible than the "perfect" place you were at during voicing. Then you add some of that stiffness and weight back during finishing. I doubt there is any way to tell whether the weight/stiffness ADDED by the extra .005" of finish is more or less than the weight/stiffness that was REMOVED by scraping the area around the bindings, sanding the top prior to finish, etc. Which is a long way of saying that, while there is always some marginal difference, I think we may well be talking about an impact that is far within the margin of error created by other steps in the building process that there's no way to know whether our final instrument will end up a little heavier/stiffer or lighter/more flexible than what we were when we finished voicing the instrument.

Everyone needs to assemble a guitar and string it up and play it with no finish. Then put a "normal" 4 mil, (.004") finish on it, and play it. Then...... put another "normal" 4 mil finish on top the the finish that's already there. The first finish makes a subtle difference, but in my case wasn't a bad thing. It "calmed" the guitar a little. The second finish, on top of the first one was almost like stuffing the body full of wet socks. It's not just the weight of the finish. Any finish is kinda like putting a glove on a guitar.


I believe there's subtle differences between finish choices, assuming they're all done right.

I haven't messed with penetrating oil finishes, but I've used most others.

I've stripped and re finished "factory" guitars that had finishes as thick as 14 mils.

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I didn't mean to say it, but I meant what I said.
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I don't by any stretch have "good ears" but I can and have heard consistent differences in the sustain and "liveliness" of hollowbody electric guitars with a thin satin finish and those with a thicker gloss finish. The satin finished instruments were much better tonally, but everyone wants a shiny guitar and they never sold as well. I'm referring to some experience I had when I worked at PRS - the instruments are their hollowbodies and the differences were audible unplugged.

On a steel string acoustic .010" of finish should noticeably affect the voice of the instrument. The tops are only about .125" thick so the finish makes up about 7% of the total top thickness. This is another situation where the infamous "cube rule" applies...and the differences are even exaggerated beyond this since the finish is most likely stiffer than the wood (the "cube rule" itself only applies for like materials and does not take into account materials with varying stiffness).

Best,
Trev

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http://www.PeakeGuitars.com

I'm in the less finish , the better camp.So i prefer FP over any.If not for having protection, i would go with no finish being the best for tone.

More finish not only will dampen the top but also increases the top's stiffness which will make the pitch rise exponentially. Here is an easy way to understand the principle and to actually measure the change. Take a scrap piece of spruce, place a piece of masking tape about where the bridge would be located and then measure the deflection. Coat the entire surface with the finish of your choice and allow the dry it over night. Next day weigh the top and measure the deflection and record the data. Repeat this process for 10 days and record the data. Now peel the tape off, measure the thickness of the tape which will tell you how thick your 10 coats were applied. You can divide that number by 10 to find out how thick each coat is and you can calculate the weight of each coat based on your data collected. At the end of 10 coats you will notice the exponential rise in stiffness and weight. Both of these factors will impact the tone of the completed instrument.

Sorry for going off on a tangent to the OP but FWIW, I too believe that a "correctly applied" FP finish on the top offers the best tone possible.

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tim...
http://www.mcknightguitars.com

It's generally accepted that guitars "play in" and gradually sound better once they have been played for some time - lots of variables, and certain top woods sound "open" more quickly than others (e.g., red cedar versus spruces), but I don't think this is a controversial statement.

This thread has made me wonder how much of that "playing in" is the result of the finish continuing to dry out, "gas off" and become stiffer. It would seem logical to me that a finish that was two weeks old when buffed would be less hard (and perhaps more damping to a top) than the same finish 6 months or a year later, (or a finish that was allowed to harden for a month before buffing).

In my case, I'm using water based finish (KTM 9). Probably some variability in terms of the finish - well beyond my level of understanding.

What do you think?

The 2 guitars I have made lately, were both the same shape and braced, thicknessed in "almost" the same way.
The first I had Fp as a sealer then trueoil.
the second Was all FP. they sound extremely different.
The trueoil guitar sound beautiful BUT mellow, had a nice overall tone but again soft and mellow, I think its mostly cause of the "oil" finish.
The FP guitar sounds extremely "crisp" you can really hear the "Wood" its sounds dry with a crisp tone. So I akm in the camp that finish is really changing the tone alot.
To answer Kelbys reply: Its a big differens to take of wood from an existing piece than to add a different material to a piece of wood. If I scrape of wood its alters the tone and pitch. But if putting on finish its being dampened. if just touching a guitars top slightly with a finger while tapping the guitar the tone is gone, so if spraying 8-12 layers of material on the top then ofcause the tone will change. and as FP is so thinly put on way less than a 8-12 layer nitro.

The only thing I think (not sure of, but think ) FP can be a negative factor for are cracks. This as the top has so little protection from humidity and weather changes.

Lars

This just kind of reaffirms what people have already said and what is known to be true, but I have had one of my guitars finished twice actually. The first time it was finished there was some flaws, once it got back from finish the second time the finish was thinner and it was astonishing the difference you could hear in the guitar. The volume increased drastically and where there was little bottom end before it now had plenty.

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--Kyle Burner--

No prob Tim your input is very valued. I completely agree with you too.

Here is some food for thought since I am a "weigh-everything-freak.."

My french polished guitar the FP added just over 1 ounce to the over all weight of the guitar.

A guitar that I finished myself with nitro added 4-5 ounces to the over all weight of the guitar.

A guitar that Joe White finished for me with cat poly added 3 ounces to the over all weight of the guitar.

In all cases the guitars were weighed before finish but after the pore filling was done so this is the weight of the finish.

If those of us who subscribe to the idea that a FPed top is sonically superior why is this so? My own thought is something that I learned from Al C. when discussing if bridge pins matter. At the end of the day the best presented reason why swapping bridge pin material may have a sonic difference to some of us was that the difference in the mass of the various pin choices is not unlike a heavier or lighter weight bridge.

So with the weights above is it possible that a FPed top can weigh an once less than other finishes? Possibly IMHO and that ounce is 28 grams not far off from the weight of most of the braces on a top either. This leads me to believe that if the finish is too thick not only as mentioned is the top stiffer now but it's heavier too and that may be the difference, if any in fact, in what we think that we hear.

What do you guys think about what I just offered, possible or am I smoking the drapes.... again....? And this notion of changing the stiffness of the top is worth a look too. We go to a lot of trouble, thin the edges, get a specific free plate tap tone, use glitter etc. to have some control over what our guitars may sound like and then we pour on the finish.... Counter productive?

I read some specs here for what a thin finish is and I would agree that .003 - .005 is acceptable depending on the type of finish of course. That thickness in FP would kill an arm for sure.... Do you give any thought to how thick you want your finish and what controls can you use to help you achieve this?

Thanks

Hesh, IMO, we not only need to consider mass but ALSO flexibility of the finish. My ear keeps getting drawn more and more to FP and I think one of the traits that it has that we don't consider is its natural flexibility. It may offer less resistance to movement therefore less inhibiting to the top's movement. Varnish also seems to share this flexibility trait as well though I have little experience with Varnish. Nitro becomes very stiff and brittle over time and we already know that Urethane and Polys are quite stiff as well. Pass me the drapes please...

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tim...
http://www.mcknightguitars.com

Being a novice at building, I don't have enough experience to have a valid opinion on finishes from the build perspective. But I have done a lot of playing over many years on a lot of different guitars. I tend to agree with Filippo
that if you're playing driving music with a medium or heavy pick in a style like flat picking, differences might be difficult to perceive, whereas if you're fingerpicking w/o fingerpicks it's probably possible to discern more subtle tonalities. That would hold especially true for the classical style of guitar, I imagine.

Something that I wonder about - wouldn't the addition of a pickguard distort the top's sound enough to mask most or all of the tiny differences in finishes? For what it's worth, on the guitars I play myself, I tend to prefer those w/o pickguards. I suppose there is a risk of getting carried away and scratching the top, but as a player - if you're scratching your tops - probably ought to reevaluate your picking technique.

John

I've done your expiement with several finishes. I believe the weight, as well as the flexibility matters alot. I used to think Nitro was the ONLY finish, because there's some really great sounding vintage guitars finished with it. Then I realized these really good sounding vintage guitars finishes were cracked all to heck. The makes the flexibility the same as, or at least close to an unfinished guitar.
I'm next in line for the drapes.

One of my jobs with I was a kid in my "mentors" shop was french polishing. I prefer other finishes due to these memories.

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I didn't mean to say it, but I meant what I said.
http://www.brackettinstruments.com/

I agree 100% the flexibility is what makes a FP finish among, if not the lease dampening finishes. Most steel string players hate it because they see the pick scratches and loss of sheen due to handling as a negative attribute despite the ease in returning it to its pristine sheen with very little effort. But classical players tend to prize tonal attributes over the cosmetic shortcomings of shellac and varnishes

The funny thing is most of those same steel string players would give there right arm to own a 1920 Martin whose shellac finish is extremely worm and dull. Go figure.

One thing to keep in mind, if there is 2 ounces difference in the weight of a french polished guitar and one from Joe White, the bulk of the weight difference is on the sides, back, and neck. So not that much difference in weight on the top.

If we accept that the flexibility of the finish matters, could some of you compare the flexibility of some of the differennt sprayed finishes? For example, how does the flxibility of Nitro, EM-6000, urethane, and spar varnish (like Rick Turner and Muthers use) compare? I probably won't french polish initially on a steel string so a little more info on the sprayed finishes would be nice.

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Formerly known as Adaboy.......

Kyle and I had both our guitar refinished at the same time. So we had the benefit of hearing them with two different finishes. Same type of finish (poly), but two different ones.

I'm in agreement with Kyle's statement that his guitar was much better after the 2nd finish.... however....

My guitar was not near as loud after refinishing as it was before. I should have kept (been happy with) the "warts" and kept it (the original finish) for the sound.

The finish work was amazing - but I'm here to tell you that two guitars - two finishes - both poly finishes - and the guitars changed drastically to our ears.

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P A U L B U R N E R
Burner Guitars

Some years ago Martin Schleske did a very careful study of the effects of violin finishes, but he included nitro and shellac. He put the same amount of each sort of finish on strips of wood, and noted the changes in weight, stiffness, and damping, re-testing again over time to track changes. The biggest effects were on cross-grain spruce strips, as you'd expect.

Basically, any finish that contained oil raised the damping factor: the rate of energy dissipation as the piece vibrated. That went for oil varnishes and for drying oil finishes. The straight oils tended to be absorbed, and did not form good protective films, so they would have had to be re-applied to be effective. This adds more weight, and damping, so plain oils seem like a bad idea if damping is not your friend.

Film-forming finishes tended to add to the stiffness of cross grain spruce strips. Lacquer added the most stiffness, followed by shellac, iirc. Lacquer also had the lowest damping: in fact, the damping of a lacquered cross-grain strip seems to have been lower than that of a plain one. Shellac had the same effect, but, again, to a lesser degree.

There is no 'ideal' finish; in fact, IMO, there are not even any 'good' finishes, in the sense that they all have pretty big drawbacks of one sort or another. Any finish done well, and put on thin, seems to work OK from an acoustic standpoint, although I do much prefer to FP a classical top if at all possible. Given the difference in high-frequency content of the different types of strings, I don't think a low-damping finish is as important on a steel string as it is on a classical.

The fact that all finishes have their problems does not mean that there are not some really bad ones out there. For a while we used a water-based finish in the shop I was in, and after a couple of years it became apparent that is was not all that one could have hoped. For one thing, it tended to react with perspriation and turn into chewing gum on necks. My partner decided to re-do the cloudy finish on one of his guitars, and proceeded to scrape the stuff off, without removing the strings. Every few minutes he would play it a bit, and you could hear it getting better. We tossed the stuff.

Interesting that this post came up when it did....

As a Noob... I was assuming that my finishes so far are on the Extra-thick side... It sure seems like I brush on about 1/2 quart of Varnish to get the darned thing coated... But.. I also do a whole lot of levelling and sanding out bad brush work, drips, etc between coats....

When I was chiseling the varnish off of Oakie's bridge location... I decided to measure a couple of the varnish shavings that shaved off... (Behlen's Rock Hard, Thanks Al...)

I was amazed... I measured 3 -- All were at or below 0.002" thick!

Now, granted.. there is a thin, hard layer absorbed into the soundboard spruce that had to be scraped off... but it was applied heavily diluted.. Could not have been more than 0.001" -- so the total finish thickness was less than 0.003"... with my money on close to 0.002" there in the lower bout....

I think a 0.010" thick layer of Finished/Polished/Done varnish on a Guitar top would probably take me 3-4 gallons of varnish to build at my current rate! I would easily believe it would be nearly that on the Back though... as my goal is to build some finish thickness on the back and sides for protection if nothing else...

Anyway, at the end of the day, I really wonder if you can hear much difference between any "Hard" finish that is finished out after all the levelling and polishing at under 0.003"... Not saying you can't or you can... I just wonder.

Thanks

John

This is a great thread and very much what I was hoping for! Thanks everyone for your participation!

Tim your point that the flexibility of the finish is important is a excellent point. To sum it up so far we want thin, flexible finishes that are tough enough for the particular kind of playing that an individual guitar will encounter.

John I have a FPed L-OO here that I built to be very light weight and have minimal finish. It has only enough shellac on it to offer the very least amount of protection. It sounds clearly different than my other guitars and much more like when I have strung up a guitar prior to finish. Subjective statement? Yep but at some point if we discount every observation for lack of empirical data we just may step in that thing that looks like, but we have no evidence that it is, a pile of....well you know.

Al your partner's experiment indicates that you guys like to smoke the drapes too - I mean that you could hear the finish as well. Great example!

The other take-away from your post is that oil finishes do damp more so than other finishes and it can be a bit of a long walk on a short pier too with additional finish required over time hence increasing the problem of damping.

Paul thanks for that my friend. So you guys can hear the finish too. It makes me wonder if any finish is capable of adding anything pleasing to the sound of a guitar?

Darryl's question is an excellent one and I would like to hear people's thoughts regarding how the various finishes stack up for flexibility? Anyone care to comment please?

Good point Michael and I still wanna build and own for myself a guitar with a shellaced top.

Woody fear not there are lots of drapes left enough for all.... So with your memories of FP you have tennis arm?

John pickguards are a great thread in the works.... But Ervin has something to say about them too on his DVD and it is not positive.....

More thoughts please?

I don't like pickguards as i believe they are tone killers just like most finishes.They restrict top movement which i believe is the biggest tone killer.

It's kinda like geting the top exactly how we want it..................and then gluing the bridge on


Right elbow from pitching baseball, left elbow from FP

If a top is too thin, too light, or too...........something else, a thick finish (or any finish) might actually help. Also, tone is subjective. I've refinished several manufacturered guitars, and they all sounded better after the re finish. I strip them with a heat gun, but I'd say it would be next to impossible to strip a finish without removing some wood. There's always a few nicks and scratches to sand out. Most "manufacturered" guitars are overbuilt, so a re finish (and the slight thinning of the top) is going to make them sound better. Again, tone is subjective.

I would build a guitar, finish it, record it, re finish it with something else, record it, and so on, but I bet the top would loose a little thickness with every re finish. It wouldn't be a fair comparison.

_________________
I didn't mean to say it, but I meant what I said.
http://www.brackettinstruments.com/

This is a really fascinating thread. One thing that jumps out at me is the idea of a guitar left free of any finish whatsoever. It would get dirty and stained, of course, but that might be kind of cool. Am I being daft?

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George :-)

Corky:
I very strongly feel that KTM9, being water based, puts a lot of water into the wood that it is sprayed onto. After it skins over, and with usually zpoxy underneath, that water is trapped between the two hard layers and takes a LONG time to escape. I also have wondered about " opening up", I am beginning to think that the phenomenon is mostly a matter of the solvents (either thinner or water) finally evaporating out of the finish. I do know that I don't level sand until I can't smell any "paint smell", that indicates to me that the KTM9 is hard enough to sand and polish. Afterwards, it takes another two weeks for the newly released solvents to finallly dissipate . I would bet dollars to donuts that if I sanded again that there's still more solvents in the paint.
I'm thinkin that maybe some of the newer multipart finishes that chemically cure and have fewer solvents might " open up" faster................. Mikey

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