Nitrocellulose vs. Other Finishes

[Scratch]

Re: Would you buy a polyester-finished Guild?

Sure. It would go nicely with my Nehru...

 

[taabru45]

trust me on this, a painter would rather be using lacquer based products than ones that require isocyanate to cure.[/quote]

I remember years ago a professional painter asking me "Do you see any old painters around?" at that time....the answer would be....no.....Steffan

 

[capnjuan]

... I remember years ago a professional painter asking me "Do you see any old painters around?" at that time....the answer would be....no.....Steffan

There are old sailors, there are bold sailors, but there are no old, bold sailors.

 

[adorshki]

Re: Would you buy a polyester-finished Guild?

Keep in mind that polyester will remain water clear, no aging and that you can't repair a spot, you need to address the entire surface. Then there's the warm glow of lacquer that you just can't even come close with polyester.

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.

 

[adorshki]

If it (apparently) isn't possible to produce identical guitars - both with the same finish - with identical tone, I don't know how it's possible to compare two identical guitars with mis-matched finishes.

You have hit it squarely on the endpin.
I can rest assured that Mythbusters will never be able to bust my myth. (I think nitro's better) :lol:

 

[jazzmang]

Re: Would you buy a polyester-finished Guild?

I'm all for traditional nitro. Nitro ages beautifully, is easily repaired, and is just traditionally in line with what Guild has proclaimed its all about - timely history, and old world craftsmanship.

 

[Ridgemont]

Ok, It seems there needs to be an additional bit of technical clarification in this thread about the differences between lacquer and various forms of "poly."

First off lets start with the major difference between lacquer and "poly." Folks they are all synthetic polymers, the only difference is when they are made, how they are made, and how they are applied. In the context of nitrocellulose, plants make the polymer cellulose, we extract it, and then we nitrate the hell out of it. I can tell you from personal experience that this process produces plenty of chemical waste that has the potential of polluting our environment. We now have nitrocellulose which is kept dissolved in organic solvents which are then shipped to guitar shops. They apply this already made polymer to the guitar and allow the volatile solvent to evaporate. Out of curiosity, what did they use before acetone as a solvent for nitro?

Now lets talk about "poly" and the application process. I keep "poly" in quotations because it is really just a coined term by us which is pretty broad and to me doesn't say much. The major distinction between "poly" and lacquer is when the polymerization process takes place. In cellulose, the plant polymerizes glucose into cellulose. In this "poly" process, we spray monomers of the eventual polymer onto the guitar and then initiate the polymerization process through the introduction of an outside initiator whether it be UV light, heat, or a chemical source depending on the type of monomer. Here we initiate a chemical reaction that the worker is exposed to whereas in lacquer such as nitrocellulose, the only person exposed to such chemical reactions is the person in the lab.

So what types of "poly" are there in the guitar world? We have talked about polyester, polyurethane, neither of which are formed by UV initiation. That is most likely polymethylmethacrylate (PMMA) which is initiated by radical formation. While they are all different and require different initiators, we should remember that they are all chemically formed after they are applied to the guitar. I will not get into polyester since I am not convinced that it is actually used in guitar manufacturing. Polyurethane uses a combination of isocyannate, alcohol, and probably some type of amine initiator. You mix them together, spray on and possibly heat. The isocyannate and alcohol will react and create the polymer coating. Now with PMMA, UV light is required and this is probably what Taylor uses. I will not delve too far into it, but the PMMA is self reactive when exposed to a high energy light source. So upon exposure to UV light, PMMA reacts another PMMA and a polymer is created.

So this probably brought more confusion, but hey I tried. Are they all man made? Yes. Do they all produce toxic waste? Yes. While they are all different chemically, we should be focusing on their physical properties which is a bit more interesting. Nitrocellulose can still be somewhat dissolved when the right solvent is applied with a little heat. This means chips and cracks can be cleaned up nicely. The "polys" of interest here cannot be dissolved with organic solvents therefore they cannot be repaired. We have already talked about thermal expansion so I won't get into that. I am most interested in restrictions caused by the coating when a wood base layer is vibrated. But that is what this thread is all about.

 

[capnjuan]

If it (apparently) isn't possible to produce identical guitars - both with the same finish - with identical tone, I don't know how it's possible to compare two identical guitars with mis-matched finishes.

You have hit it squarely on the endpin.
I can rest assured that Mythbusters will never be able to bust my myth. (I think nitro's better) :lol:

Hi Al; Frono earlier suggested that which finish contributed the most to tone was a matter of opinion but opinions are usually based on facts, the interpretation of facts, and reason.

I wonder if there are enough facts to form an opinion about guitar finishes and tone. If not, it's more of a matter of preference than anything else; ... coke v. pepsi for example.

 

[capnjuan]

Strong stuff Ridgemont; thank you.

 

[hideglue]

Dang, Ridgemont, don't confuse us with the facts.

Kidding, of course.
Thanks for the educated breakdown --- great stuff!

I guess the isocyanate reference explains the amount of Super Glue I've used as a touch-up finish to polyurethane?

 

[Ridgemont]

I guess the isocyanate reference explains the amount of Super Glue I've used as a touch-up finish to polyurethane?

Super Glue is actually methylcyannoacrylate, which based on your experience, must be compatible with polyurethane. I would emphasize that their polymerization processes are somewhat similar. Superglue actually requires water as an initiator, and this is consumed during the polymerization process. So don't run to the sink if you get some on you. Run to Home Depot to pick up some acetone.

 

[fronobulax]

Ok, It seems there needs to be an additional bit of technical clarification in this thread about the differences between lacquer and various forms of "poly."

Thank you. I fear I actually understood what you were saying, probably due to a misspent summers working as a lab tech an R&D lab in New York State Health Department.

 

[bluesypicky]

Wow Ridge!!!!! Give us a notice or somethin' before lashing out posts like that!
Now I'm picking brain particles from all over the walls, as my head spontaneously exploded somewhere in the middle of the second paragraph....
Say.... how about going ringing doorbells and running away in hysterical laughter now?
Well done essai Sir.
I take it you have some kind of chemistry education?

Don't think about all that when you play though, it might distract you. :lol:

 

[Walter Broes]

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.

 

[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.

 

[Ridgemont]

Ok, It seems there needs to be an additional bit of technical clarification in this thread about the differences between lacquer and various forms of "poly."

Thank you. I fear I actually understood what you were saying, probably due to a misspent summers working as a lab tech an R&D lab in New York State Health Department.

Unfortunately, I would argue that, from an acoustics standpoint, the whole chemical side of things is rather worthless and not really relevant to the conversation. That is unless you are really interested in the ease of repair between finishes. When I say acoustics, I mean a vibrating source creating soundwaves that we perceive as noise. I am not a polymer physicist or physicist nor do I pretend to be. But the way this conversation is going, that is who we would need to talk to for some light to be shed on the issue.

BTW, this is a good thread. Oh and where is the love for the hand rubbed satin? :mrgreen:

 

[hideglue]

Oh and where is the love for the hand rubbed satin? :mrgreen:

Good point. HR is the finish with the least amount of applications (read: barely any).
Stands to reason (or not) that HR is closest to the wood's bare resonance.

 

[West R Lee]

A great post by Dane from another thread which is relevant to this discussion.

http://www.acousticguitar.com/article/d ... leid=24089

West

 

[curt]

Take a look at the two guitars, any of poly's sisters aren't going to look like that over time. Maybe a monomer, dimer, trimer but not poly....

 

[adorshki]

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

Good question. I was half-joking about Mythbusters, since they don't always construct a valid scientific method, (and I made a joke about 'em earlier in the thread), but I was acknowledging your observation that it's technically impossible to make two absolutely identical instruments, so it'd be pretty much impossible to do a true scientific comparison. With guitars, anyway.

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.
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.
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.