Nitrocellulose vs. Other Finishes

[adorshki]

Re: Would you buy a polyester-finished Guild?

... All that, and everything I've read indicates nitro has better acoustic properties when new, and WILL get better as it ages. Poly simply won't. It IS as it will always ever be. I will admit I'm open to more evidence about poly.

Hi Al; what did you read that indicated 'nitro has better acoustic properties'? I'd be open to more evidence about nitro.

When we discussed this about a year ago, the point was made that nitro's crystalline structure is a better resonant mediium than cross-linked polymers, to try to put it in a nutshell.
A gross and sloppy comparison would be like the difference between leaded crystal glass and plastic water bottles.
At the thicknesses at which the finishes are applied, I'm back to my original question, which is "not sure if human ears can hear it".
Like you, trying to be realistic and keep an open mind. The actual physics may say nitro's better, but, "At what magnitude are the differences actually perceivable?" might be a better question.

 

[capnjuan]

I wonder if there are enough facts to form an opinion about guitar finishes and tone.

so it'd be pretty much impossible to do a true scientific comparison. With guitars, anyway.

Yes; the top being fastened to the guitar changes things.

Meanwhile Ridgemont has asked a question to put the focus where it should be, in my opinion, on what the effect of the finish is on the top's ability to resonate.

My apologies ... but I thought that's where it had been; what - if any - impact either of the two finishes has on resonance ...

The last time this was taken up, I believed the guys who explained that polyester won't allow wood to resonate as freely as nitro. Assuming that's correct, that's the "factual" basis for my opinion and preference. Operative phrase being "I believed". I gotta admit though, I'd love to see some kind of test data for the "real" facts.

Sorry if this is a re-hash for you ... I must have skipped school that day :wink:

If I was gonna try to construct a comparison test, I'd start with a thin sheet of metal and cut it in half so I'd be as sure as I could be that each sheet was identical to the other. Paint one with nitro and the other with poly. Put a mic in front of each one, wired into an O-scope, and start tapping. Even better, cut several different length/width combos from one big sheet to see variations in response of the finishes at various resonant frequencies.

Yes; that might work. You'd know the vibration enhancing (or damping) characteristics of the finishes.

But if you can't make two identical guitars with the same finish that produce the same tone, then there must be other factors besides finish that effect tone of which resonance is considered an important part, no? There's a problem with establishing an optimum: how much top movement is good? If you spoke to ten qualified guitar builders, their ideas of what is 'too tight' or 'too loose' might vary all over the place:

Luthier A: "I like my tops tight so they resonate (move back and forth at the desired frequency) well"
Luthier B: "I like my tops loose enough to move; too tight and the tone is snuffed out"

If, as the mythology has it, all the pieces and parts of the guitar contribute to tone, how would anybody be able to isolate the effects of finish on resonance / top movement / tone one way or the other?

Not trying to be needlessly argumentative ... I can understand preferring one finish over the other. I personally think Swiss tastes better than cheddar but that's not science or opinion .. it's just preference. Not saying there's anything wrong with preference ... it's when preference morphs into fact. I like the look of nitro, I've never spent much quality time around late-model Taylors, and I'd like any guitar I shipped or received to be free from imperfections. Past that, I don't really have an opinion on finishes one way or the other.

 

[capnjuan]

Re: Would you buy a polyester-finished Guild?

... All that, and everything I've read indicates nitro has better acoustic properties when new, and WILL get better as it ages. Poly simply won't. It IS as it will always ever be. I will admit I'm open to more evidence about poly.

Hi Al; what did you read that indicated 'nitro has better acoustic properties'? I'd be open to more evidence about nitro.

When we discussed this about a year ago, the point was made that nitro's crystalline structure is a better resonant medium than cross-linked polymers ... I got it; at the molecular level, it's harder. At the thicknesses at which the finishes are applied, I'm back to my original question, which is "not sure if human ears can hear it". Not sure either. Like you, trying to be realistic and keep an open mind. The actual physics may say nitro's better, but, "At what magnitude are the differences actually perceivable?" might be a better question.

I don't know the answer to that either; it's just tough buying into the proposition that one or the other is 'better' for resonance/tone if in fact the difference is imperceptible.

While we're on the subject, what is the value of an undiscovered oil well?

 

[Ridgemont]

The Captain is correct in saying the quality or tone of the guitar is based on many different factors. I know for me, tone is important but also aesthetics plays a big part as to whether I like the guitar. But, since the OP has conveniently omitted all other variables out of the equation as evidenced by the title of this thread, I would like to say that I like where Al is going with this.

In the grand tradition of a nice science fair poster, I had a couple of thoughts about experimental set up to determine which is the victor and which is to be tossed out with the bath water. I do not know much about electronics so maybe someone with an engineering background could help out:

Take 2 rectangular pieces of bookmatched spruce and coat each one with your choice of finish. Suspend each plank so only 2 opposite sides are secured (with glue similar to that in a guitar). Attach a velocity pickup to each piece of wood and connect the pickup to a monitoring system. You could then drop a small rubber ball from a specific height onto each plank and record the vibrational pattern of the wood. Come back several years later and try again to see if age makes a difference. Very crude for sure but not completely crazy.

 

[hideglue]

I like where your heads at, Ridgemont, but the same small rubber ball would to be the (suspected variable) constant from beginning to several years/ months/ days end.

 

[Ridgemont]

I like where your heads at, Ridgemont, but the same small rubber ball would to be the (suspected variable) constant from beginning to several years/ months/ days end.

No problem. This is developing idea. We could address this in several different ways. We could change the ball to something that doesn't deteriorate over time, but we should be causious in our choice in that we do not choose a material that will damage the surface of the finish. If we keep using the rubber ball and have deterioration as a possibility, we could keep a record of the ball's mass to ensure consistency. Also, the volume of the ball should be recorded. If deterioration is evident, then replace with a new ball of same mass and volume. The height of release should remain constant, and to reduce the amount of human error, we could devise a contraption to release the ball automatically.


Another thought would be to vibrate the top with a reflex hammer, but then we would not be using gravity as our force and would need a device to swing the hammer with consistency.

 

[adorshki]

But, since the OP has conveniently omitted all other variables out of the equation as evidenced by the title of this thread, I would like to say that I like where Al is going with this.

Right, I took it we were trying to isolate out the effect of the finish independently of other variables. That's why I didn't base the test on wood. I suspect wood wouldn't be as consistent as a piece of metal. I'm thinking variations in the grain pattern would affect densities even in bookmatched pieces. I'm thinking the density patterns themsleves affect resonance. That might be a big factor in why no two instruments ever sound exactly the same even if all the measurements and construction techniques were.
It's all wild speculation based on widely diverse readings, but Mythbusters thinks enough of it to be calling me back for a second interview next week. :lol:
[/quote]

 

[FNG]

Re: Would you buy a polyester-finished Guild?

I typically play laminated hollowbody electrics, and if I could get a really good deal on a "recent" X160 Rockabilly, which I think is usually poly, I'd get it - I don't think it would influence the sound much, and the guitars I play a lot really do get played a lot, in which case a poly finish might even hold up better.

Given a choice for the same money, I'd choose traditional nitro, it looks and wears nicer. But if I like a guitar, the way it plays and sounds, the type of finish won't keep me from getting it.

Like this?





Define really good deal... :lol:

 

[bluesypicky]

It's all wild speculation based on widely diverse readings, but Mythbusters thinks enough of it to be calling me back for a second interview next week. :lol:

[/quote]
Now that is cool!!! Get it done Al!!! :wink:

 

[adorshki]

Another thought would be to vibrate the top with a reflex hammer, but then we would not be using gravity as our force and would need a device to swing the hammer with consistency.

With a device you could engineer a consistent or variable the energy of the "tap". I Like the idea of letting gravity be a constant, but with a variable tap force you could then measure the effect of different levels of "tap amplitude".
See, on Mythbusters they'd forget all about the "spectrum" a guitar needs to reproduce and focus on one type of test only.
That observation caused 'em to toss my resume though. :lol:

 

[Walter Broes]

Re: Would you buy a polyester-finished Guild?

FNG, that's a beautiful guitar, but I'm afraid I was being a little hypothetical for the time being - I don't really have the money for something like that right now, even if you cut me a REALLY good deal, ha. Plus, I'm not too crazy about orange, no offense. Now if it was one of those black ones..... :shock:

 

[adorshki]

Re: Would you buy a polyester-finished Guild?

While we're on the subject, what is the value of an undiscovered oil well?

Ah, you're not gonna trick me with that one! Whatever someone was willing to pay for it that day! :lol:

 

[FNG]

Re: Would you buy a polyester-finished Guild?

FNG, that's a beautiful guitar, but I'm afraid I was being a little hypothetical for the time being - I don't really have the money for something like that right now, even if you cut me a REALLY good deal, ha. Plus, I'm not too crazy about orange, no offense. Now if it was one of those black ones..... :shock:

No worries, Walter!

 

[West R Lee]

Impossible to reach a conclusion or maintain a stance in this one as none of us are chemists who have or could ever sonically test the two finishes in a straight up, objective comparison.

I will say this, and it's just personal opinion. If I were a major guitar manufacturer, or a little guy for that matter, I doubt I would say....."Hey, we'd like to use nitrocellulose lacquer, but it takes too long, costs too much money and puts us at odds with the EPA, so we give you a UV polyeurathane finish. It just easier!" So they say it's harder (no doubt) and equal to or better than nitro. I still haven't figured out exactly why one would need a UV finish on a guitar? I've never had one lay out in the sun, and none of mine are parked next to a window. :?

I do buy Carl's logic that wood doesn't need to breathe, but feel that it is entirely possible that nitro might allow wood to expand and contract better than plastic, and if that's "breathing", or just expanding and contracting....well . We have a sizable contingent here who honestly believe that a played guitar sounds better via that logic, and I just don't know, so I certainly can't disagree. And if vibration and expansion and contraction are what make the top go round (and sound better over time), I'm all for it.

I suppose I still find myself in the pro-lacquer camp.

West

:? Hm, I thought I'd mentioned how finishes effect sound as being the real issue of this thread back several pages. And there's not an "OP" of this thread, the thread was moved here as it was part of a different thread origionally.....think Chazmo moved the appropriate posts here. It has been an interesting one.

West

 

[capnjuan]

Re: Would you buy a polyester-finished Guild?

While we're on the subject, what is the value of an undiscovered oil well?

Ah, you're not gonna trick me with that one! Whatever someone was willing to pay for it that day! :lol:

No; not really a trick question ... just one that doesn't have a straightforward answer ... something like: nitro or poly?

 

[fronobulax]

Wow. I am really impressed with the quantity of informed opinions. Still learning.

A couple of observations.

Someone mentioned "hand rubbed satin" as a finish that is in some sense less intrusive. If we are only considering tone and sustain (and not the protective aspects of a finish) how does that compare to other finishes? Could it be that the finish in some way "improves" those properties, compared to unfinished wood? Or are we in the realm of "maybe you can hear a difference but I can't"?

An interesting attribute of nitro finishes is that people believe, and there is supporting evidence, that the sonic qualities of a nitro finished guitar vary over time in a way that the other finishes do not. So do experiments performed a week after the finish has been applied really tell us anything about what the guitar will be like in 20 years? On the other hand, if the non-nitro finished guitar sounds good enough today, who cares if it doesn't sound subjectively better in 20 years, as long as it sounds the same? In fact that raises a question - is it rational to buy a new guitar today in anticipation of what it will sound like in the future? :wink:

Lots of comments about repeatable science. We will never have identical samples and dismissing the proposed experiments on that basis seems to be a red herring. After all, I still believe certain prescription drugs are going to help me even if they have not been tested on my clones. As long as we are engaging in thought experiments we should start out with wood samples that are as close to identical as possible. If they were cut from the same piece of lumber before the experiment that is about the best we can do. We probably make measurements before and after the finishes are applied. Since the wood vibrates we probably should measure the amplitude of the vibration when the wood is "excited" at various frequencies of interest to guitar builders. (I seem to recall a device that can do that by clamping one end and inducing a machine controlled motion in the other so the "rubber ball" effect probably doesn't apply). By the time we finish this and publish it, several folks will come out of the woodwork (*snicker*) point out what is wrong with our experiment and design and run their own to correct the deficiencies. Eventually there will be a body of work to support informed hypothesis generation.

And yes, I am probably taking this whole discussion too seriously, but I am having fun.

 

[curt]

The fact is people like what they own or have purchased and we all, especially me, need to be careful not to put them in defense mode. I just looked at the poll and it's not really a good sample yet, I am a little surprised that many don't care what finish is on their guitar which leads to more questions. I'm sure there are some that own guitars that hang on the wall and are seldom played or they don't care as long as they sound good to them which is really what it's all about. I'm old school and can tolerate one of the poly(s) on an electric but can't stand it on an acoustic but that's me. There will be a time when nitro will be eliminated and when that time comes know that I will have a few 55 gallon drums of it to last me a lifetime.

 

[capnjuan]

:? Hm, I thought I'd mentioned how finishes effect sound as being the real issue of this thread back several pages. And there's not an "OP" of this thread, the thread was moved here as it was part of a different thread originally.....think Chazmo moved the appropriate posts here. It has been an interesting one.

Hi West; finish and sound ... that's still the subject of the thread. Chazmo did cobble this thread together; it started out as a veer to Grot's thread about receiving #99 with stress fractures in the top. The discussion there stopped being about Grot's guitar and focused on the strengths and weaknesses of nitro so ... a new thread about sound, nitro, and poly. So far ... because he actually knows something, Ridgemont has been named Chairman of the Chemistry Department. :wink:

 

[fronobulax]

I am a little surprised that many don't care what finish is on their guitar which leads to more questions

Coming at this from the perspective of an electric player I have had no reason to care. My reasons for caring now are cosmetic and stewardship. I want to know what my finishes are because I would rather not repeat the previous owner's experiment involving a guitar hanger with a rubber coating.

Moving forward, I am only going to care if I can get functionally equivalent instruments that only differ in the finish. My definition of functionally equivalent will obviously differ from other people's and implicit in my definition is the assumption that I don't hear as well as I used to and so am unlikely to perceive a difference. For me the analogy is to a car. I find the car I like for transportation and if it doesn't come in my favorite color buy it anyway.

I'm actually surprised so many people do care but I am learning that there actually are reasons to care.

 

[cjd-player]

This thread certainly has gone down a slippery slope. :lol:

My post, which is now the OP in this thread, was in response to Grot's cold-checked guitar.

The UV-cured polyester finish that is used by many guitar companies and many independent luthiers is harder than nitrocellulous lacquer (does not scratch as easily) and does not cold check. It does not become damaged by contact with vinyl and other chemicals. To me, that makes it a superior finish compared to nitro lacquer. It protects that expensive instrument better.

The effect on tone, if there is one, is irrelevant. Some have made the assumption that a guitar top is to resonate as much as possible. That simply is not true. Different builders brace and thickness the tops differently because each wants the top to resonate in a particular way to give their signature tone. Guilds and Martins and Taylors and Gibsons sound different for intentional reasons. The builders do not want the top of every guitar to resonate as much as possible. They want to control the resonance. So in the overall picture, the effect of the finish, if any, is irrelevant to the tone. They are going to get their tone regardless of the finish.

We all buy the guitar that sounds the best to us. If it happens to have a UV cured polyester finish it is better protected in both the short and long term than a nitro lacquer finish. Period.