Nitrocellulose vs. Other Finishes

[capnjuan]

I'm not sure I see the point of this test.

To prove whether or not nitro finish on a piece of spruce will crack if you put it in a freezer.

Just a guess, but I'm thinking it could be cold combined with rough handling during shipping in some instances. It would be interesting to know whether or not it checks when stressed right out of the freezer.

Not sure about the rough handling; were that a major factor, then people reporting top cracks would be reporting back/side cracks as well but they don't seem to get complained about as frequently ... and if the nitro-covered backs and sides don't crack as readily, then why is it only nitro-finished tops do?

True or not, it's been said that Taylor and other poly-finished guitars don't show as much/any top cracks; wouldn't it be true that they get as poorly-handled as Guilds or other nitro-finished guitars? Do nitro-finished guitars put out a vibe that says: "Rough me up!"?

 

[Pike]

Good point. It would also be interesting to know if older, more cured (harder) finishes check more often than newer ones.

 

[capnjuan]

Good point. It would also be interesting to know if older, more cured (harder) finishes check more often than newer ones.

Agree; according to the lore, as nitro ages it continues to harden and shrink making it more brittle. If so, it would be more susceptible to extreme variations in temperature, eccentric force from rough handling, and the phases of the moon ...

 

[Ridgemont]

Good point. It would also be interesting to know if older, more cured (harder) finishes check more often than newer ones.

Agree; according to the lore, as nitro ages it continues to harden and shrink making it more brittle. If so, it would be more susceptible to extreme variations in temperature, eccentric force from rough handling, and the phases of the moon ...

It would be interesting to see how an old piece of nitro handles Curt's temperature test. Maybe that old forklift smashed Guild that Curt has could be used for such a test. But we would have to wait for the next full moon.

 

[cjd-player]

But if the test that Curt did is correct, then we can safely say that rapid temperature changes do not cause fracturing in nitrocellulose finish on wood.

Actually we can't because the way the test was done put the finished surface in compression. And something in compression will not usually crack.

 

[mbaker824]

Re: Would you buy a polyester-finished Guild?

I have a question.
Isn't the finish that Taylor uses different than the Poly finishes that are on most Asian built guitars?

As I understand things, The finish that Taylor uses isn't the thich, restrictive coating that some poly finishes are known for.

I have owned 3 Asian built guitars with poly finishes and all 3 sounded restricted. Like the finish was holsing the sound back.
The most noticable to me was a Recording King RD-227 but the GAD JF-48 also felt and sounded like the vibrations were being restricted.
Was it the finish?
I have no way of knowing but many members of the Acoustic Guitar Forum sure feel that poly finishes restrict the guitar's top from vibrating as much as it could.

Taylor has a good write-up on their polymer finish on their web site: http://www.taylorguitars.com/guitars/fe ... pment.aspx. Here's the key part, from a player's perspective:

Using a polyester-type resin that's UV-activated, the new finish proved to be easier to use than Nitrocellulose-type lacquers. It's clearer, so the wood grain/coloration is more natural and distinct. It also doesn't yellow like lacquer, resists scratching and cracking, and doesn't cold-check. It contains as many "solids" as thicker finishes, so a thinner application provides the same protection while allowing the tonewood to breath for a more natural tone. It also ages the same way that we like a good lacquer finish to age, allowing the guitar to "open up" as it's played over the years.

Taylor's finish was custom-developed, so I'm sure it's not the same as what Asian manufacturers (or any other, for that matter) are using. I know a lot of players say poly finishes inhibit tone, but I'd bet real money they wouldn't be able to tell the difference in a blind test, assuming it's a high-quality poly finish. A lot of fans of other guitars don't like the Taylor sound and might blame it on the poly finish - but I like the Taylor sound just fine. I do think it's true that Taylors aren't as loud, and are more balanced tonally (less pronounced low end) than some other guitars, but I don't believe that has anything to do with the finish. I own an all-mahogany custom Taylor that sounds spectacular, and because of the clearer, thinner poly finish the beauty of the wood grain stands out like no other mahogany guitar I've ever seen.

Mark

 

[jazzmang]

Re: Would you buy a polyester-finished Guild?

I actually like how lacquer yellows (actually, it takes on a golden glow, IMO). Very beautiful!

 

[mbaker824]

Re: Would you buy a polyester-finished Guild?

I actually like how lacquer yellows (actually, it takes on a golden glow, IMO). Very beautiful!

I don't disagree at all; I like that look, too. I hope I haven't given the wrong impression - I don't dislike nitro finishes at all, it's just that I don't dislike poly finishes either. My D-25 is 20 years old and has taken on a golden hue that looks very nice, although the finish has chipped in a couple of places.

Mark

 

[Ridgemont]

But if the test that Curt did is correct, then we can safely say that rapid temperature changes do not cause fracturing in nitrocellulose finish on wood.

Actually we can't because the way the test was done put the finished surface in compression. And something in compression will not usually crack.

Could you expand or clarify? What do you mean by compression? Was the material (nitrocellulose) compressed by placing in the freezer?

 

[Taylor Martin Guild]

I have seen and played a lot of new Martin guitars at my locak GC.
Many of them were shipped in the winter.
None of them have shown any cracking on the tops.
My guess would be that because the guitars are new, the finish is still more durable.
Aging and drying must be a factor in the shrinkage and cracking.

One more side note.
My Guild D-55 is a 2005 model.
I got it last year.
The finish on the neck will still soften and get sticky when I play the guitar.
It must take a lot of years for the finish to get hard.
Any comments?

 

[Ridgemont]

Interesting. It seems several are suggesting that it is well aged lacquer that is susceptible to cold checking. Maybe we should take a poll. How many people have experienced cold checking and what were the ages of the guitars in question?

Also, maybe a freezer test by Curt with some well aged nitro from an old guitar would be fun to see as well.

 

[adorshki]

Re: Would you buy a polyester-finished Guild?

I'd bet that if you took two identical guitars, and finished them one with nitro and one with a poly finish, you'd be hard pressed to tell the difference in sound.

I submit that after 10 years you might. I haven't seen anybody saying poly improves with age yet.

In fact I'm now fairly certain my D40 is poly.

Stick it in the freezer overnight Al, then pull it out and put it under a blow torch.....we'll find out if that sucker is nitro! :lol:
West[/quote]
Yer just sayin' that 'cause it's a Corona, aren'tcha?

 

[cjd-player]

But if the test that Curt did is correct, then we can safely say that rapid temperature changes do not cause fracturing in nitrocellulose finish on wood.

Actually we can't because the way the test was done put the finished surface in compression. And something in compression will not usually crack.

Could you expand or clarify? What do you mean by compression? Was the material (nitrocellulose) compressed by placing in the freezer?

The unfinished side absorbed moisture and expanded creating a convex curve. The finished side could not absorb moisture because of the finish. The result was the curved board as seen in the photos. The finished side became a concave curve. Since the finish was applied when the board was flat, bending the finished side into a concave curve put the surface fibers and the finish into compression along the curve. When you bend anything that is initially straight, a piece of wood, a piece of metal, a piece of paper, etc., the convex surface is in tension and the concave surface is in compression.

 

[adorshki]

If it's lacquer it should be visibly obvious. If that doesn't work then smell it as soon as you take it out of the case, if it's lacquer it'll have a sweet smell other than wood.

The lack of visible aging shrinkage is, as I said, my biggest single clue right now. I'm thinking an 8 year old guitar with about 350 hours of playing on it ought to be showing SOME signs. The other two sure as h-ll are.
I know the sweet smell you mention, it used to be pretty powerful on the D25 for a long time. And now that you mention it, I don't think the D40 does that either. It's got a kind of scent of its own, but it's always been pretty mild.

 

[Ridgemont]

The unfinished side absorbed moisture and expanded creating a convex curve. The finished side could not absorb moisture because of the finish. The result was the curved board as seen in the photos. The finished side became a concave curve. Since the finish was applied when the board was flat, bending the finished side into a concave curve put the surface fibers and the finish into compression along the curve. When you bend anything that is initially straight, a piece of wood, a piece of metal, a piece of paper, etc., the convex surface is in tension and the concave surface is in compression.

You bring up a good point, and something I had not considered. By the looks of the photos taken, it seems that the square of wood is bowed before and after freezing, although more exaggerated after the freeze. If this is true, and Curt can help confirm on this one, then the bending process would be a variable that would have to be dealt with. Is there a way to keep the wood straight at all times? I guess a brace would do it.

 

[adorshki]

I guess a brace would do it.

With an idea like that, we could build some kind of musical instrument! MIRAC! :lol:

 

[West R Lee]

Re: Would you buy a polyester-finished Guild?

I'd bet that if you took two identical guitars, and finished them one with nitro and one with a poly finish, you'd be hard pressed to tell the difference in sound.

I submit that after 10 years you might. I haven't seen anybody saying poly improves with age yet.

In fact I'm now fairly certain my D40 is poly.

Stick it in the freezer overnight Al, then pull it out and put it under a blow torch.....we'll find out if that sucker is nitro! :lol:
West

Yer just sayin' that 'cause it's a Corona, aren'tcha? [/quote]

:lol: No Al, I'm sure it's a fine guitar, but with all the testing going on comparing the finishes, I couldn't resist.

West

 

[curt]

Nope, the brace and sides help to control movement not enhance it. I'll wait 'till everyone is done scratching their chins and see how many hoops I have to jump through.

 

[chazmo]

Re: Would you buy a polyester-finished Guild?

I have merged the "Would you buy a polyester-finished Guild?" poll thread with this thread. This may have resulted in some interleaving that looks a little funny. Sorry about that.

Sorry for any confusion.

Oh, by the way, the results of the poll were as follows.
Any acoustic/electric that Guild builds; i.e., I don't care about the finish 52% [ 16 ] x
New models (acoustic/electric) I'd consider on the low-end only. Don't mess with the Traditionals 10% [ 3 ]
I'd only consider a hollow-body or solid-body; acoustics should be nitro 13% [ 4 ]
No, all new USA Guilds should always be nitro. Period. 26% [ 8 ]

Total votes : 31

 

[GuildFS4612CE]

How's about the obvious, here. :idea:

The wood, and it's coatings of...whatever...expand and contract at different rates when exposed to...whatever...

Since the two are not moving in unison...something's got to give. :roll:

Whatever...dudes. :wink: :lol: :lol: :lol: