Finishes

adorshki

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Long ago and far away we had one of those marathon threads about finishes, but that one was just about "poly vs nitro".
The recent revelation that Oxnard is using catalyzed varnish on new D20's and M20's caused me to look into the use of varnish as an instrument finish over time, and I found a fascinating (well, to me, anyway) article, here:
http://www.aitchisoncellos.com/publ...-about-the-cello/understanding-cello-varnish/
One of the details that caught my attention was that the original 1000-year old recipes called for pine resin combined with linseed or walnut oil and boiled slowly.
Walnut's been favored by our member KostasK for fretboard dressing ever since I've been member here.
Another fact gave me a chuckle:
"the extraordinary fact that linseed oil varnish becomes alcohol soluble after about 200 years."

And we worry about how long it'll be before we need a neck reset.
Let the veering begin!
 

davismanLV

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Ooooooh-kay, Al!! You hooked me on this one and I'm ready for a debate, BUT... I'm a little tanked and I need to PLAY my guitar for a while but.... before I read the article and knowing a little about finishes, I'm going to just say how AWESOME my Taylor poly finish is. It keeps its shine (people think it's thick but it's not, it's been measured) and it handles a beating a keeps on repeating. Lacquer is awesome for it's repairable qualities. Shellac is the same way. But they're fragile and ..... this conversation will go on through the end of the planet. I think. Unless aliens have a better finish.

So, tomorrow, sobriety. Then a more considered response. Okay, amigo? :stupid:

p.s. - leaving these bombs in the evening when I'm at Happy Hour and then BOOM!! You're gone!! Not fair..... LMAO!! :encouragement:
 

kostask

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I honestly don't know the difference between "catalyzed varnish" and the regular plain old varnish, to be honest. The regular old varnish type has been used on musical instruments for hundreds of years on piano, violins, mandolins, and all sorts of musical instruments. as well as other uses for the protection of wood. My assumption would be that the catalysed varnish is a two part system involveing a chemical catalyst, unless it is Heat or UV catalysed.

DavismantV, your Taylor's finish is no dobut beautiil, and tough. It is not, however thin. You may consider it to be thin, but how thin is thin? Is a .010" thickness thin, or is it thick? Hand applied nitro finishes, after final buffing out, are in the range of .003-.004". The other part is that poly finishes are never completely dry, as they actually remain somewhat flexible, even after many years. It can be thought of as an extremely thin rubber/latex sheet covering the guitar. Nitrocellulose lacquer will continually out gas solvents until there are only solids left, which is part of what contributes to the so called "opening up" phenomenon; it is true that most of has to do with the wood, but the finish (by completely drying out or "crystalizing") has a small. but significant effect on improving tonal quality on nitro finished guitars as time goes by. I don't think it is possible to spray poly as thin as nitro, due to the chemistries involved. By the way, for the record, when I say nitro, I mean the real, solvent based stuff, not the "catalyzed" or water based so called nitro finishes. I know that nitro is almost unavaiable these days due to environmental concerns, but there are still hand builders using it.
 

chazmo

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. . . By the way, for the record, when I say nitro, I mean the real, solvent based stuff, not the "catalyzed" or water based so called nitro finishes. I know that nitro is almost unavaiable these days due to environmental concerns, but there are still hand builders using it.

umm.. kostas, are you saying that there are different kinds of nitrocellulose lacquers??? I.e., some more environmentally-friendly than others. I was not aware of that. I thought NCL was NCL. And, it is my understanding that that NCL was used to build most USA Guild acoustics since the company's inception, except for possibly some exceptions in Corona and recently with the M-20/D-20s in Oxnard.
 

Rayk

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My Blueridge poly seems thin compared to my ibanez electric which is like heavy gauge pick thick hahahahaha
I can see the wavyness and feel it in the top would but I don't really how thick it is but it sounds great and won't check and I can sit outside by the fire and not worry . ;)

Tom you get ranked a lot can you do a live stream for us ? :)

Speaking with my Builder I asked about finishes , I mentioned my dislike of nitro because of its checking issues .

He told me he uses nitro but s new kind that is very check resistant and it's some high end stuff. I don't know what it called though .

Either way not taking it anywhere close to a fire ! Lol
 

kostask

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Chazmo:

I don't know that the waterborne or catalyzed lacquer finishes are chemically the same as real, solvent based nitrocellulose lacquer, but they are often represented as such. I just wanted to make the distinction, as the catalyzed lacquers (not as sure of the water borne) will not continue to harden up as time goes on like the solvent based lacquers will. In the case of the catalyzed lacquer, once the catalyst has been used up (in the case of chemical catalyzer) and the catalytic reaction is completed (UV catalyzed nitro), there will not be any significant hardening of the finish, pretty much the same as with poly finishes. As I have stated above, I don't know where water borne lacquers fit.

It is the solvents in the "real" nitro that are the problem for the environment. The solvents are VOCs, and there has been a big push by bodies like the EPA to eliminate VOC release into the atmosphere for many years. This has made both obtaining real nitro more difficult, and getting a nitro paint/spray booth licensed more difficult, which is why poly, catalyzed, and water borne lacquer usage is increasing, even with hand builders.

The solvent based nitro finishes are more delicate, and will, in time, tend to check/crack more often, due to their loss of flexibility as the solvents continue to out-gas ("crystallize"). in return for that, you get better tone. Take your pick, either crack resistance/appearance, or better tone. Right now, you can't have both in the same finish.
 
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davismanLV

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Here's a great video about what's happening to poly finishes at Taylor. I'm not using this as any type of argument but just putting it out for informational purposes. The great thing about poly is it's beautiful and mostly it's DURABLE. Anyway, great video to watch.

 

kostask

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Thanks for that. I know that .006" is doing really well with a poly finish. Taylor getting it down to .0035" is a real breakthrough, and will definitely make a difference in tone. It would be interesting to find out how they got that done. From the past, poly was too thick/viscous to be sprayed with a gun that had nozzles as thin as the nozzles used to spray nitro. Looks like they have figured out how to get the poly thinned out/lower viscosity enough to allow for a thinner poly finish. Taylor does have the financial resources to do that kind of research, and they seem to have the motivation as well.
 

adorshki

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I honestly don't know the difference between "catalyzed varnish" and the regular plain old varnish, to be honest. The regular old varnish type has been used on musical instruments for hundreds of years on piano, violins, mandolins, and all sorts of musical instruments. as well as other uses for the protection of wood. My assumption would be that the catalysed varnish is a two part system involving a chemical catalyst, unless it is Heat or UV catalysed.
Kostas, right, didn't realize you hadn't seen this link I posted in another thread:
http://www.woodshopnews.com/columns...47-for-resistance-varnishes-are-tough-to-beat
He goes over some formula variations for different categories of varnish in there.
It just got me started thinking varnish was the original finish like you say, and that led me to that cello maker's article.
Purely for those of us who get off on that stuff, no intentions of starting a "which finish is better debate".
I actually had a buddy with an old beat up cello and was saving to get it re-finished, it was way gone. I had no clue about what it takes, but I'd certainly love to hear a genuine varnish finished guitar with some age on it.
p.s. - leaving these bombs in the evening when I'm at Happy Hour and then BOOM!! You're gone!! Not fair..... LMAO!! :encouragement:
tumblr_lw80vfKeXS1qaselw.png

Certainly you wouldn't be accusing me of actually planning it that way, would you?
 

adorshki

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umm.. kostas, are you saying that there are different kinds of nitrocellulose lacquers??? I.e., some more environmentally-friendly than others. I was not aware of that. I thought NCL was NCL. And, it is my understanding that that NCL was used to build most USA Guild acoustics since the company's inception, except for possibly some exceptions in Corona and recently with the M-20/D-20s in Oxnard.
Because it surprised me it stuck with me, but Hans confirmed recently we saw a mid 80's FS46 or FS47, one of those acoustic/electrics with the "fake soundhole" that had a poly finish from Westerly. They did experiment with it there for a very short time.
Also Corona for sure used poly on at least some of the electrics like Aloha Joe's X170 (150?), but not acoustics, and I think Westerly did too, but that I can't remember for sure.****See edit below****
Chazmo:
I don't know that the waterborne or catalyzed lacquer finishes are chemically the same as real, solvent based nitrocellulose lacquer, but they are often represented as such.
https://www.google.com/search?q=water+based+NCL+lacquer&hl=en&biw=1024&bih=653&site=imghp&tbm=shop&s
A quick google search yields consistent references to acrylic bases in water-based lacquers and a couple of direct distinctions from "real" NCL lacquer. I was always under the impression that nitrocellulose requires the highly volatile solvents, it's not soluble in water. That quick search seems to confirm it.
I just wanted to make the distinction, as the catalyzed lacquers (not as sure of the water borne) will not continue to harden up as time goes on like the solvent based lacquers will.
And like you I'm in the school that believes that's a good thing about NCL.
What surprised me in that cello article was the time spent on explaining that it in the case of varnishes as small degree of flexibility as the finish ages is seen as very desirable.
Specific reference was made to the fact that if the oil/pine resin is boiled too hot and/or too quickly, the resulting varnish is too hard.
What we have in pine resin is the source of the VOC's that break down the oil into a different polymer and walnut and linseed also contain high concentrations of VOC's, for oils with their viscosity. Apparently the degree of heat affects what kind of polymers are formed.
For anybody unaware: Polymers are just chains of molecules with repeated component molecules and the length of the chains and structure of the sub-units and the strength of the bond between them are what determine a given polymer's properties.
So varnish appears to be one of the world's oldest man-made polymers.

**** update 12/11/18, just posted an update clarifying that Westerly used lot more "poly" than I remembered when I originally started this thread.
See post #79 here.
 
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adorshki

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Here's a great video about what's happening to poly finishes at Taylor. I'm not using this as any type of argument but just putting it out for informational purposes. The great thing about poly is it's beautiful and mostly it's DURABLE. Anyway, great video to watch.

I can't help but wonder if I was that guitar if I'd feel like I was being probed by an alien.
 

davismanLV

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Great link, Snidely.... er, I mean, Al!! It explains a lot about finishes. I remember learning the hard way about the differences between lacquer and poly finish. I layered the poly coat after coat. Then after a good dry time, I started to level the finish so I could then polish and buff it out. It was almost perfect and then in one spot, I went through the top layer of poly. It just broke through and then there's this SPOT where ..... well, it's just ruined. Lacquer is very forgiving, AND it also is its own solvent.

I wonder why they don't use the water based Polyacrylic on guitars? Easy to use, and dries hard as a rock. Maybe it's TOO hard? No flexibility? I dunno.
 

adorshki

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I wonder why they don't use the water based Polyacrylic on guitars? Easy to use, and dries hard as a rock. Maybe it's TOO hard? No flexibility? I dunno.
Actually that google link shows at least one reccomended for instruments (by its maker) right on the first page.
Without digging into it, and knowing them, I'd bet that what Taylor is using is already the most cost-effective solution they could find.
It also occurs to me that even if there was a cheaper or more durable option "workability" is probably a big consideration too:
How easily does it spray, how thin can it be sprayed, how long to dry and sand/buff between layers.
In a volume manufacturing environment those issues become relevant, like a hideglue neck joint needing to be set pretty quickly compared to Tite-bond.
Sometimes it's not that something takes too long but maybe that there's not enough time to fix goofs before the material's unworkable.
As has been mentioned NCL is extremely forgiving for workability and that's often forgotten when comparing to more durable finishes even if they might be acoustically equal or even superior. (Don't worry, I'm not abandoning my preference for NCL, I'm just getting educated to the possibility)
That workability might also have played a larger role in the original manufacturing use than we've considered so far.
It also wouldn't surprise me to learn that when it began to be used on instruments it was touted as a low-cost alternative to varnish and the instrument maker purists were dead-set against its use compared to varnish. It's just how things seem to go, you know?
The original industrial application was auto paint.
From Wiki:
"Slow-drying solvent-based lacquers that contain nitrocellulose, a resin obtained from the nitration of cotton and other cellulosic materials, were developed in the early 1920s, and extensively used in the automobile industry for 30 years....General Motors Oakland automobile brand automobile was the first (1923) to introduce one of the new fast drying nitrocelluous lacquers, a bright blue, produced by DuPont under their Duco tradename.
These lacquers are also used on wooden products, furniture primarily, and on musical instruments and other objects.... The nitrocellulose and other resins and plasticizers are dissolved in the solvent, and each coat of lacquer dissolves some of the previous coat. These lacquers were a huge improvement over earlier automobile and furniture finishes, both in ease of application and in colour retention. The preferred method of applying quick-drying lacquers is by spraying, and the development of nitrocellulose lacquers led to the first extensive use of spray guns
."
THAT was kind of interesting.
Kind of a symbiosis in mass manufacturing.
 
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kostask

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Just so there is no confusion (there seem to be a lot of "polys" floating around), when I was talking about poly finishes, I was talking about "polyester" and "polyurethane". Polymers (see definition by adorshiki) of various types are present in all finishes.
 

kostask

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.....

And like you I'm in the school that believes that's a good thing about NCL.
What surprised me in that cello article was a the time spent on explaining that it in the case of varnishes as small degree of flexibility as the finish ages is seen as very desirable.
Specific reference was made to the fact that if the oil/pine resin is boiled too hot and/or too quickly, the resulting varnish is
too hard.
What we have in pine resin is the source of the VOC's that break down the oil into a different polymer and walnut and linseed also contain high concentrations of VOC's, for oils with their viscosity. Apparently the degree of heat affects what kind of polymers are formed.
For anybody unaware: Polymers are just chains of molecules with repeated component molecules and the length of the chains and structure of the sub-units and the strength of the bond between them are what determine a given polymer's properties.
So varnish appears to be one of the world's oldest man-made polymers.

Flexibility in varnish can be a good thing (as when used strictly to protect wood from the elements or water, in spar varnish), or a bad thing (for musical instruments, where a very hard finish will help tone). All depends on what the intended purpose for applying the varnish is.

One of the so called secrets to Stradivarius and Guarneri violins is their finish. A lot of work has been carried out to try to discover the exact formula used in order to try to get modern violins to come closer to the violin tone of the old masters. This is another example of how important the finish is to a musical instrument. A finish can only detract from the sound of the bare wood instrument; the ideal finish minimizes the tonal loss while protecting the wood. I have heard a couple of assembled guitars prior to their having their finish sprayed on. The sound is remarkably good, and extremely loud, all out of proportion to what would be expected out of a guitar of its size (000/OM sized). Still great after the nitro was sprayed on, but nowhere near as impressive.
 
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kostask

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Davisman LV:

Some do. See LMI's website (lmii.com), go to Finishes > Finishes > KTM Water-Based Finishes (KTM-9). They specifically call out John Greven and Mike Doolin as using this type of finish, two exceptional hand builders. They seem to be happy with it, according to the quotes.

Another point: Hard is also relative. Poly finishes feel like they are hard. They are not, they are somewhat flexible, which is why they don't crack and are as durable as they they are. Nitro starts off somewhat flexible as well, but as the solvents outgas over time, it becomes pretty much only solid resins, with no flexibility at all. That helps the tone come through, but also makes it more crach/chip prone. Hardness can be measured, but needs to be done with instruments, not by look/feel.

Anecdote: In 2004 or 2006 (I forget the exact year), I was at the Healdsberg Guitar Festival. Pretty much heaven for any person who has a passion for guitars. Anyway, I was walking around with my guitar builder friend, all the while wishing that I had an infinite supply of money so that I could take every guitar home. Anyway, as we are walking around admiring all of the handmade works of art. my guitar making buddy stops me pretty much in the middle of the main exhibition floor. I asked him what was going on. He asked if I could spot all of the non-US made guitars from where I was. I said no, not without going to each exhibitor's stand and reading their information sheets. He said he could spot every single one, right from where he was. Figuring he was yanking my chain, I said, bull. He siad its easy. Just look for the guitars with the tops that shined the most. I siad that isn't right. He said that all of the US hand builders were using either poly. or water based finishes, and when polished out, the nitro finished guitars always come out with a higher, smoother shine. He was right.
 
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Christopher Cozad

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..I wonder why they don't use the water based Polyacrylic on guitars? Easy to use, and dries hard as a rock. Maybe it's TOO hard? No flexibility? I dunno.

Davisman LV:

Some do. See LMI's website (lmii.com), go to Finishes > Finishes > KTM Water-Based Finishes (KTM-9). They specifically call out John Greven and Mike Doolin as using this type of finish, two exceptional hand builders. They seem to be happy with it, according to the quotes…

First, a deep bow to NCL; long live the king! If I were not so incredibly sensitive to solvent-based lacquer I would still be using it. It goes on thin, sounds great and looks even better. And it is easy to repair. But it can be deadly!

KTM-9 is my (current) personal favorite. A water-based urethane/acrylic, I believe it to be every bit as durable as NCL, goes on just as thin, and I still retain mental and lung capacity after spraying. With a nod to environmental and personal health friendliness, I love French Polishing a shellac finish, though I (currently) only offer shellac on request. A French Polish is downright therapeutic to apply, and it is quite possibly the thinnest (and safest, healthwise) finish available. Repairs are a snap! Sadly, it is also the least durable finish. It looks and sounds great, but it is happiest in the arms of a very discerning owner.

Following John’s lead, I apply KTM-9 over an epoxy pore seal. I believe Chris (AcornHouse) made a comment recently regarding the current penchant for thorough pore filling. I tend to go really light on the filler, as I personally like the look and feel of the wood with some pores visible. I do not personally care for the “plasticky” appearance of a perfect pore fill. Regardless, the epoxy contributes to a depth and luster visible in the final product that is otherwise not obtainable, something we have come to expect from NCL.

Regarding the environment, Greven’s shop is beneath his living quarters, in his basement. He has a small spray station that is wide open to the rest of his shop. He catches the spray solids in a furnace filter that sits in front of a fan that simply vents outside his home. NCL requires an explosion-proof exhaust system, personal filtration and protection, and your next-door neighbors probably aren’t homeowners a mere 12 feet away. When I last visited John, I was impressed with the utter lack of overspray and odor. I mean, the man is putting out the equivalent of a guitar a week and all I smelled was sawdust!
 

rwmct

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Flexibility in varnish can be a good thing (as when used strictly to protect wood from the elements or water, in spar varnish), or a bad thing (for musical instruments, where a very hard finish will help tone). All depends on what the intended purpose for applying the varnish is.

One of the so called secrets to Stradivarius and Guarneri violins is their finish. A lot of work has been carried out to try to discover the exact formula used in order to try to get modern violins to come closer to the violin tone of the old masters. This is another example of how important the finish is to a musical instrument. A finish can only detract from the sound of the bare wood instrument; the ideal finish minimizes the tonal loss while protecting the wood. I have heard a couple of assembled guitars prior to their having their finish sprayed on. The sound is remarkably good, and extremely loud, all out of proportion to what would be expected out of a guitar of its size (000/OM sized). Still great after the nitro was sprayed on, but nowhere near as impressive.

I remember a guitar mag from a decade or more ago, they interviewed a couple of electric guitar makers. On the topic of finishes, they both said that if they had their way, there would be almost no finish on their guitars at all, but that they can't sell them that way. They have to look good in the store.
 

kostask

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Same as what the master builder in the Taylor video said. The majority of it is to look good so that the guitar sells, but the finish is also there to keep the top from getting dirty and to keep liquid damage (anything from body sweat from hands to just random sprays a variety of liquids) to a minimum for all of the guitar's wood. The top, being a very porous wood (spruce and cedar specifically, although mahogany is also porous) is quite susceptable to damage.
 

adorshki

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Kick-starting this puppy back to life after several comments about finishes in another thread:
http://www.letstalkguild.com/ltg/sh...-leaving-Guild&p=1737462&posted=1#post1737462

The aging part if you ask me haha yeah it will look all shiney and new if you don't use it . My old Yamaha was poly and she aged wood wise now I had it outside a lot in the sun over the yrs she turned a nice Amber color that was in Florida beach side . Should have never sold it ,

If it will get beat up looking and the top can still color change and deliver great tone that works for me better then a kracle glass collection on my guitar . But hey talk about it anymore they have crack resistant NCL Yaaaaaay

I might be doing a NCL repair as my Cv fell over and chip in between the tuner and the NCL Is stained now that gets my goat ��
And lemme reiterate the whole point is to explore the pros and cons of the various finishes without trying to prove one is "best", in spite of personal preferences.
Hey, I might wind up getting converted myself.
:friendly_wink:

So...getting back to the original point, Guild's now using 2 finishes for sure: "catalyzed varnish" and traditional NCL.
Let's make very clear that a unique property of of true NCL lacquer is that readily dissolves and blends if new NCL applied over it, it's its own solvent and crystallizes much like hide glue (or amber or pine resin) does as it dries.
Any of the water-based lacquers won't be chemically identical; on drying, NCL is only re-soluble with organic solvents, which are the "VOC" 's that are the primary environmental concern.
Nitrocellulose is insoluble in water therefore any lacquer that's waterbased cannot be an NC type and I suspect they're acrylic lacquers.
Which aren't re-soluble like NCL.
Here's an interesting discussion about the state of waterborne finishes from a banjo forum in '09:
http://www.banjohangout.org/archive/149219
Consensus seems to be that water-based is still somewhat inferior to what they call "spirit-based" lacquers, recognizing that was 7 years ago.
Let's make it clear that polyurethane based finishes aren't very eco-friendly either, releasing large amounts of formaldehyde as the cure and in fact the expandable poly foam that used to be so popular for conformal cushioning packaging up until the late '70's was one of the first targets of environmental regs. That's why you don't see it anymore, in the USA.
Essentially the issue with "polys" as a generic class is that they are chemically catalyzed and once the catalyzation is complete, that's it, no more evolution of the finish.
Is that a good or a bad thing?
The only "real" "bad" I can think of is difficulty of repair if needed.
Varnish:
As mentioned is a generic term for a protective coating but traditional instrument types are chemically is closer to NCL than polys as they also continue to evolve as they age.
Guild's use of the term "self-catalyzing" definitely means that their varnish carries a catalyzing as it's applied, the inference being that it needs no more than some air curing time, as opposed to the increasingly common UV-curing technique used on "true" polys.
It is possible to repair poly. Taylor has a course on how to do it with their finish. Doing it without leaving any witness lines is a whole different story. It is extremely difficult. Poly finisheS, after the catalyst has done its job, cannot be un-catalysed....
Once the catalyst is consumed in the process of hardening the poly finish, the poly finish is done, it won't change chemically in any way. Nitro continually outgasses, getting thinner with the passage of time. The other part of this is that nitro also crystallizes, meaning the out-gassing of the solvents leaves solids behind, These solids tend to improve the tone of the guitar. While it may look to be very hard, poly is actually somewhat flexible, and doesn't change over time as discussed above. This acts as a very slight tonal absorption. That will NOT get better with time
Here's where I think the real "tone question" comes in:
In at least a couple of sources (the one I linked above and this one Ray cited http://proguitarshop.com/andyscorner/nitro-vs-poly ) that varnish and NCL lacquer is actually "softer" than poly and that a certain amount of flexibility is actually desirable.
So I get that yes the finish needs to be able to expand and contract with the wood's humidity fluctuations, and in the case of a varnish finished cello especially, the whole top is actually a giant speaker cone after all, and it does need to be able to vibrate as freely as possible, and it seems that poly, no matter how thin, would tend to inhibit that as it's far less "stretchable" than traditional oil varnish or NCL.
Perhaps polyester based finishes (which are really the norm for guitars right now as I understand it) do offer a degree of "flexibilty" even though their surfaces are supposed to be "harder"?
That does tend to contradict my traditional understanding of Kostas' point that NCL hardens and gets more resonant, but perhaps the 2 issues should be addressed as an interacting phenomena with NCL, which isn't present with the other 2 finishes?
 
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