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What is the knock against polyurethane?
I have used Poly for many instruments...I have noticed that many builders prefer other finishes. What is the general source, if any, of reluctance of using Poly---I find it easy to apply, good drying, and deep luster if applied in thin coats with sanding prep between applications.
Feedback, please.
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Re: What is the knock against polyurethane?
Quote:
Originally Posted by
pelone
I have used Poly for many instruments...I have noticed that many builders prefer other finishes. What is the general source, if any, of reluctance of using Poly---I find it easy to apply, good drying, and deep luster if applied in thin coats with sanding prep between applications.
Feedback, please.
My understanding is that nitro is thinner, therefore helping the instrument "breathe,"
Also, an instrument coated in nitro will wear naturally, whereas one coated in poly will essentially look new forever (except for the chips and dings).
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Re: What is the knock against polyurethane?
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Re: What is the knock against polyurethane?
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Re: What is the knock against polyurethane?
I've heard the comments regarding polyurethane affecting tone before.
First, are there any studies supporting that viewpoint?
Second, polyurethane is a curative finish as contrasted to a evaporative one like lacquer. Generally varnishes like oil varnish or spirit varnish are considered to be superior to lacquer for instrument finishes so that concept seems counter intuitive to me?
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Re: What is the knock against polyurethane?
Quote:
Originally Posted by
Bernie Daniel
Generally varnishes like oil varnish or spirit varnish are considered to be superior to lacquer for instrument finishes
As a lifelong professional finisher (NOT instrument builder nor luthier) I keep up with a lot of these posts but rarely dare to chime in.
When making a general statement like this one, it's not very helpful unless you state just who considers oil or spirit varnishes to be superior to lacquer. I understand that many people do. I understand that even some of the great luthiers of today do. I also believe that maybe one or two just know that there are some in the market who believe this, so they use those finishes and advertise them as a selling point, whether they are fully sold on the concept themselves.
It is not a given that oil or spirit varnish are superior to lacquer as a final finish on a musical instrument as a general fact; at least I'm unaware of any scientific evidence of that.
What I would say to the OP is that film finishes are an interesting study in and of themselves, and that perhaps one should experiment with different materials and techniques. If someone in a forum says that the film you are using is ruining the sound of the instrument you produce, and yet you know better, then don't worry about it. Do what you do, just don't expect to make many converts, and don't expect to find any scientific evidence on why different makers prefer this over that in the final finish.
What you'll find are a full spectrum of beliefs that range from "the finish makes no appreciable difference as it's contribution to the sound is too small" to "I am one of the very few who has the actual recipe used by Stradivarius and I'm not telling you what it is".
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Re: What is the knock against polyurethane?
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Originally Posted by
pelone
if applied in thin coats with sanding prep between applications.
I think you answered your own question. Many use Poly as a quick finish and it often is way too thick.
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Re: What is the knock against polyurethane?
Quote:
Originally Posted by
Mark Gunter
As a lifelong professional finisher (NOT instrument builder nor luthier) I keep up with a lot of these posts but rarely dare to chime in.
When making a general statement like this one, it's not very helpful unless you state just who considers oil or spirit varnishes to be superior to lacquer. I understand that many people do. I understand that even some of the great luthiers of today do. I also believe that maybe one or two just know that there are some in the market who believe this, so they use those finishes and advertise them as a selling point, whether they are fully sold on the concept themselves.
It is not a given that oil or spirit varnish are superior to lacquer as a final finish on a musical instrument as a general fact; at least I'm unaware of any scientific evidence of that.
What I would say to the OP is that film finishes are an interesting study in and of themselves, and that perhaps one should experiment with different materials and techniques. If someone in a forum says that the film you are using is ruining the sound of the instrument you produce, and yet you know better, then don't worry about it. Do what you do, just don't expect to make many converts, and don't expect to find any scientific evidence on why different makers prefer this over that in the final finish.
What you'll find are a full spectrum of beliefs that range from "the finish makes no appreciable difference as it's contribution to the sound is too small" to "I am one of the very few who has the actual recipe used by Stradivarius and I'm not telling you what it is".
Well the main point of my post was" "What is the evidence that polyurethane varnish kills the tone"?
This point was stated or implied in the two posts before mine.
I made a comment in passing about the perceived merits of varnish versus lacquer. I stated many people prefer varnish to lacquer on instruments. I think that statement is pretty well documented by the market place.
A lacquer finished Gibson F-5 Fern will sell from between $5,500 to 7,000. That identical instrument with a varnish finish albeit with with a Sitka top & aliphatic glue construction) will command at least $2,000 - 3,000 more. Q.E.D.?
You later agree and also state many do consider varnish superior to lacquer so I do not think we have any disagreements there.
Later you assert that you do not think varnish is superior to lacquer as an instrument finish.
Well guess what? I AGREE with you on that too! And certainly you are correct that there is no scientific evidence to show that. I have long felt that varnish is not worth the money (again my opinion) and I would not pay a nickel extra for it.
Now for the record the whole point of my post - it was a question or a challenge. What is the evidence that polyurethane varnish kills the tone?
So it looks like we agree on almost everything regarding this topic so I'm not sure why you commented on my comment! :))
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Re: What is the knock against polyurethane?
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Originally Posted by
colorado_al
I think you answered your own question. Many use Poly as a quick finish and it often is way too thick.
Well no that is a little off the mark and does not address the central question. You answered a "process question" that may or may not happen. Improper application should not reflect poorly on the finish but on the finisher.
If you put oil varnish or nitro lacquer on "too thick" it will kill the tone too.
The question raised by the OP was what is it about polyurethane varnish per se that makes people claim that it "kills the tone" (see posts # 3 & #4).
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Re: What is the knock against polyurethane?
Since I have chimed in here, probably only fair to state my own preferences, though that's pretty meaningless in the big scheme of things and there are some great luthiers and finishers here who have different preferences - and as luthiers, their opinions count for more.
1. Nitrocellulose lacquer or pre-catalyzed lacquer
Most finishes I do use one or the other of these. The reasons are ease of use (spraying), fast drying time, and in the case of nitrocellulose, ease of repair/touch-up, etc. since this is a fully reversible finish. The pre-cat is even easier to work with, and offers a very small degree of greater protection because of its "plasticized" nature. I find most pre-cat lacquer finishes to be a easier to repair and manipulate than other "plasticized" (cross-linked) finishes like conversion varnishes and polymers. I don't believe that lacquers have any intrinsic ill-effects on the sound of an instrument, but nitrocellulose lacquer is prone to checking after a number of years. Note: I do not use "sanding sealers"
2. French polish (spirit varnish)
I use shellac-based finishes with a french padding technique extensively in repair work and as final finish on some small items including musical instruments. The reason it is second to lacquer is that it is labor-intensive. The benefits are that you have the greatest degree of control since this is applied by hand with the thinnest possible coats, it is fully reversible thus easy to repair/touch-up, and can be built to a nice film. Less durable than the lacquers. No intrinsic ill-effects on the sound.
3. Oil
I use oil finishes (not oil varnishes) for certain applications, and only rarely on musical instruments.
4. Water-bourne poly
I use this for convenience in certain settings, but never on musical instruments. Cross-linked, non reversible finish.
As for polyurethane, oil varnish, etc. I do not use them - I mean I have used them, but these types of finishes are rarely a finish of choice for me. They tend to build too quickly, they are difficult to manipulate in many ways, they cure too slowly, they are not reversible finishes.
By reversible, I mean a finish that dries or cures to a film but is otherwise not chemically altered, so that re-introducing the proper solvent will re-liquefy the film.
By cross-linked, I mean a finish that undergoes a chemical change so that the molecules become cross-linked, and re-introducing the solvent does not re-liquefy the film.
By oil, I mean natural oils that have not been cooked and chemically altered, like linseed or tung oil finishes.
By oil varnish, I mean finishes that are derived from cooked oils and other ingredients that become cross-linked finishes.
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Re: What is the knock against polyurethane?
Quote:
Originally Posted by
Bernie Daniel
Well no that is a little off the mark and does not address the central question. You answered a "process question" that may or may not happen. Improper application should not reflect poorly on the finish but on the finisher.
If you put oil varnish or nitro lacquer on "too thick" it will kill the tone too.
The question raised by the OP was what is it about polyurethane varnish per se that makes people claim that it "kills the tone" (see posts # 3 & #4).
I'll repeat myself, people claim it kills tone because it is usually applied too thick. The problem is not inherent in poly as a finish, but people claim that it kills tone because their experience with poly finishes is that they are applied to heavily. Poly is more difficult to apply in thin coats as compared to French polish for example, but poly is much faster to apply and in a factory setting for less expensive instruments, the speed and reduced labor time helps to keep budgets low. This also tends to result in a thick finish which has a deleterious effect on tone. That is what make people claim it kills the tone.
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Re: What is the knock against polyurethane?
Bernie, it wasn't my intent to nit-pick you, and you are probably right that at least in the mandolin world (maybe violins too) "Generally varnishes like oil varnish or spirit varnish are considered to be superior to lacquer for instrument finishes" - and maybe in this forum as well. I really don't know, but as you've pointed out, the marketing seems to bear this out.
I'd think in the case of hand-padded finish the price difference may be justified; otherwise, I believe it is simply market hype.
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Re: What is the knock against polyurethane?
Here is more specific evidence -- in the past 6 months, I have talked with three shops that specialize in poly guitar finishing. In all three cases, the guys running the shop said essentially the same thing, "While I work to get as thin a poly finish as is possible, you will not get the quality of tone that you are currently getting from a oil Varnish and Shellac French Polish finish."
In all three cases, the bluntness and finality of their feedback was extraordinary. There was absolutely no waffling or lack of clarity in their indication that the tone would be affected in a negative way.
Steve
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Re: What is the knock against polyurethane?
I could be way off but I was always under the impression that poly was a harder and a more reflective finish and therefore the sound/tone tends to be brighter and shinnier, particularly with acoustic instruments, although there's ongoing discussion about it in the world of solid body guitars and it's thought of as less warm than a lacquer or in this case varnish finish.
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Re: What is the knock against polyurethane?
For cheaper instruments isn't the finish polyester, or more accurately catalyzed polyester? Rock-hard, often dipped like a lollipop, difficult to repair. I have read that very thin polyester can be an excellent finish sound-wise, but it's very difficulty to apply that thinly.
Polyurethane is something different, i.e. polyurethane varnish. Many high end guitar builders use high end polyurethane varnish with some success.
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Re: What is the knock against polyurethane?
+1 on finish thickness being the number one criterion.
My experience with Poly is EnduroVar, which is perhaps not a typical poly finish, but I honestly detect no tonal difference between shellac, TruOil or EnduoVar finished instruments. There is certainly a difference in both the "look" and ease of application though (though I make no distinction as to which has the "best" look, that depends on personal preference).
With regard to "reflective" finishes, what I certainly have noticed is that a high gloss rubbed-and-buffed finish will generate more highs and a brighter tone regardless of the material used in the finish. Or at least that's my rather unscientific opinion ;)
Repair-ability is a good point, certainly evaporative finishes have the edge here, though they are also less durable than some of the "harder" alternatives. Interestingly EnduroVar appears to be an in-between finish here: it seems to be almost infinitely repairable with more Var, but not much else (which is to say most solvents won't touch it). One week after delivering a guitar to a customer, he dropped it face down onto concrete, lumpy bumpy old street concrete that ripped a suave across the lower 'bout. After partially refinishing the effected area, I could (just) tell the difference between new and old finish, the customer couldn't, and one year later it's so blended together that I can't spot the repair any more either.
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Re: What is the knock against polyurethane?
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Originally Posted by
Tavy
Repair-ability is a good point ... EnduroVar appears to be an in-between finish here: it seems to be almost infinitely repairable with more Var
I've found that the pre-cat lacquers are fairly easy to repair as well, a bit trickier than the 'evaporative finishes', but worlds easier than polyurethane, oil varnish or polyester. I've only ever used two brands, Mohawk and Sherwood, but those have consistently equal characteristics.
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Re: What is the knock against polyurethane?
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With regard to "reflective" finishes, what I certainly have noticed is that a high gloss rubbed-and-buffed finish will generate more highs and a brighter tone regardless of the material used in the finish. Or at least that's my rather unscientific opinion
I need to understand this. Are you saying that buffing an instrument to a higher gloss will change its tone? I hope you're not saying that.
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Re: What is the knock against polyurethane?
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Originally Posted by
StevenS
Here is more specific evidence -- in the past 6 months, I have talked with three shops that specialize in poly guitar finishing. In all three cases, the guys running the shop said essentially the same thing, "While I work to get as thin a poly finish as is possible, you will not get the quality of tone that you are currently getting from a oil Varnish and Shellac French Polish finish."
In all three cases, the bluntness and finality of their feedback was extraordinary. There was absolutely no waffling or lack of clarity in their indication that the tone would be affected in a negative way.
Steve
That is hard and substantial evidence of what those guys (and you) believe, Steve. And regardless of what you believe, you make some gorgeous instruments with a fantastic finish.
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Re: What is the knock against polyurethane?
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Originally Posted by
colorado_al
I'll repeat myself, people claim it kills tone because it is usually applied too thick. The problem is not inherent in poly as a finish, but people claim that it kills tone because their experience with poly finishes is that they are applied to heavily. Poly is more difficult to apply in thin coats as compared to French polish for example, but poly is much faster to apply and in a factory setting for less expensive instruments, the speed and reduced labor time helps to keep budgets low. This also tends to result in a thick finish which has a deleterious effect on tone. That is what make people claim it kills the tone.
Right the knock is on how it is applied not on the finish itself. So comments like polyurethane kills tone are misguided or unfair. Thick finish kills tone -- regardless of what it is.
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Re: What is the knock against polyurethane?
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Originally Posted by
ProfChris
For cheaper instruments isn't the finish polyester, or more accurately catalyzed polyester? Rock-hard, often dipped like a lollipop, difficult to repair. I have read that very thin polyester can be an excellent finish sound-wise, but it's very difficulty to apply that thinly.
Polyurethane is something different, i.e. polyurethane varnish. Many high end guitar builders use high end polyurethane varnish with some success.
On very cheap instruments, yes. And on many solid body electrics.
But on most factory made instruments less than $1000 the finish is a sprayed on nitrocellulose lacquer or sprayed on polyurethane.
For example, the new Breedlove Crossover $500-$750 and they use sprayed catalyzed polyurethane. The finish is very nice looking, but tends to be thick in order to get a high gloss with low labor and short production schedules. I don't know how much this affects flat top guitars compared to carved/arched top mandolins.
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Re: What is the knock against polyurethane?
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Originally Posted by
Dale Ludewig
I need to understand this. Are you saying that buffing an instrument to a higher gloss will change its tone? I hope you're not saying that.
:)
I guess what I'm saying is that there is a clear difference between an instrument strung up in the white and finished rubbed-and-buffed out. With minimalist "in the wood" finishes like TO somewhere in between the two. I actually prefer the "finished" sound, it gains some clarity and focus, though perhaps some of that may be down to in-the-white tests being conducted on rather unfinished/unsanded instruments with very rough and ready tops at that stage.
Or perhaps - and this is quite possible - that I'm largely imagining this ;) Subjective old game this tone stuff!
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Re: What is the knock against polyurethane?
Quote:
Originally Posted by
StevenS
Here is more specific evidence -- in the past 6 months, I have talked with three shops that specialize in poly guitar finishing. In all three cases, the guys running the shop said essentially the same thing, "While I work to get as thin a poly finish as is possible, you will not get the quality of tone that you are currently getting from a oil Varnish and Shellac French Polish finish."
In all three cases, the bluntness and finality of their feedback was extraordinary. There was absolutely no waffling or lack of clarity in their indication that the tone would be affected in a negative way.
Steve
That's fine but am skeptical of opinions that are not based on some kind of blind testing that eliminates preconceived expectations.
Comments exactly the opposite of those you quote exist -- so where are we?
Quote:
Originally Posted by
ProfChris
For cheaper instruments isn't the finish polyester, or more accurately catalyzed polyester? Rock-hard, often dipped like a lollipop, difficult to repair. I have read that very thin polyester can be an excellent finish sound-wise, but it's very difficulty to apply that thinly.
Polyurethane is something different, i.e. polyurethane varnish. Many high end guitar builders use high end polyurethane varnish with some success.
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Re: What is the knock against polyurethane?
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Originally Posted by
Bernie Daniel
am skeptical of opinions that are not based on some kind of blind testing that eliminates preconceived expectations.
Put me down as a skeptic as well, Bernie. Steve has offered indisputable evidence of what they believe. Are they correct? Who cares. As long as Steve makes those gorgeous mandolins, I couldn't care less what he believes. (I'd like to be able to do what he does though). ;)
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Re: What is the knock against polyurethane?
well, I too think much has to do with thickness and hardness of the finish.
I have an old fender strat elite with thick poly, like end table thick. looks great. possibly adds a good deal of weight to the instrument. have no idea how it affects the sound, if at all.
as for scientific evidence, don't gots.
and imho, in this regard, Bernie makes an important point, sorta the forum equivalent of "urban legend"
(ive long believed that fingerboard material, ie rosewood, pao ferro, ebony, might make a difference, but not one I can hear, not one that has a characteristic sonic signature-try this pov on the les paul forum , and there are cork sniffers that will tell you they can hear the dif between braz and EIR on a LP fingerboard....I was pilloried by the Cars Elliot Easton for not being able to clearly hear a difference between a LP custom with ebony and an LP standard with rosewood, hard to fight that kind of thing, being merely me.....)
otoh, as we lawyers are prone to say,
I find over the years , in reading certain instrument reviews, forums, etc. often there seems to arise certain observations that are common, and not coincidental. these have weight, for me. but I have also seen a thread going one direction, and if a contrary opinion is politely inserted, the thread may reverse with a new dog pile.
tis a ponderance!
but................Charlie Derrington said in a mandozine interview that while the difference was small, a seasoned ear can distinguish between varnish and lacquer finish on an F5.
on the presumption that CD wasn't full of himself, and had enormous experience in playing, repairs, and builds, this non scientific observation carries weight with me.
personally , due to the durability, I prefer lacquer, and, while I am in the camp that most poly is way too thick, it is relatively bullet proof.
my varnish mandos seem to react a great deal more to heavy playing than does lacquer, ie cloudiness /smudgyness which must be polished out with Dave Harveys stuff, doesn't wipe clean like nitro and a bit of moisture.
I know first hand, from my heavy hand polishing out a deep scratch in my fern, Gibson does not skimp on the lacquer, ie its relatively thick. on my historic LP, its paper thin, so thin, I can see the growth line ridges on the maple in the finish surface.