Wednesday, October 21, 2009

Guitar Finish and Tone

Nitro Cellulose verse Polyester Finish
If you have looked into buying a new guitar lately you've probably heard the pitch about "Thin" Nitro cellulose based lacquer. Often the sales person or the marketing flyer accompanying the product will state that the "thin skin" allows the guitar to "breath." Horse Hockey! These same misinformed barn-yard chemists also tell us that the Nitro is cellulose based and that since wood is a cellulose then we have a shell of similar properties. Phooey! Nitrates are often synthesized from cotton rather than wood and saying that similar substrates make for a better tone is tantamount to stating that because water is comprised of 80% oxygen, we can in fact breath water at 80% efficiency. The coating; be it Nitro or poly based specific purpose is to prevent wood decomposition and protect the wood from the elements.

Wood resonates better with nitro than poly. False. This statement leads to another popular myth where people believe that the guitar with aged nitro is cured better. However, Nitro remains active and it is thinning as it ages whereas poly finishes harden and do not remain active or thin over time. Nitro casting solvents can be used to redissolve the Nitro finish and fix finish defects and scar's - In this case I like Nitro a lot. With Poly if you have a chip the only practical remedy is to fill the crack or dent with cyanoarcrylates. Filling the crack is a repetitive exercise with the fill spot still being apparent as a dull lack lust spot on the finish at best. Another myth is that Nitro is more labor intensive and takes longer to dry. Once again, Nitro doesn't EVER dry as it starts thinning the moment it is applied. Both Polyester and Nitro Cellulose take about the same time to dry and that is dependent on the ambient environment.

I reason that the rage regarding Nitro finish is due to the distressed or relic guitar market and disinformation regarding the "coolness" or playability of these guitars. No doubt these guitars have a certain panache and lovely patina. I think these instruments play well but do not necessarily believe that Nitro finish or better yet - scratches and lacquer checking make better tone! After all, guitar pickups determine sound reproduction as do the strings and electronic components. These processes have a far greater impact on tone than the finish on the guitar.

In regard to finish repair: unfortunately, poly finishes cannot be dissolved with the casting agent, sanding or chemical erosion is the only method of poly surface removal. For this reason, repair is very difficult but the advantage to Poly is that the finish is far more durable than Nitro. So does Nitro coated guitars have better tone by virtue of the finish? No.

Guitar production companies are NOT pouring in millions of dollars into surface finish research because with music there is the omnipresent mystic. The Mojo Voodoo effect, the Spinal Tap amp that goes to Eleven effect - It's one more! The thin skin is marketing hyperbole and nothing more. All you guys that want to flap your gums about the guitar breathing can save it. Show me the data and you better have FR's and DP's nailed and if you don't know what I am talking about then I doubt you could provide me with objective scientific data. The finish is a preference and the two finishes do fell different to each, that is a given fact due to the nature of the material.

Now, I prefer Nitro on the body and unfinished necks. Nitro cellulose on the guitar neck leaves a tacky feel for me. Beware during outdoor gigs, Suntan lotions dripped onto the instrument by perspiration will effectively break down Nitro well! Beware as simply laying your guitar on your vinyl case can blister your finish. Store your guitar in your case!!! Poly is resistant to blistering, sweat and staining. Ultimately if I was playing my guitar and sweating up a storm it is the unfinished neck that would help me play my best. There is a price to pay for unfinished necks as they are far more reactive to relative humidity and the lack of finish is likely to make the neck less stable and prone to torsion - a grave affect. I like the Nitro coated body for selfish repair simplicity. I also find myself a slave to fashion and prefer the relic look. Again, I like the relic look on the body because it's harder for me to see where I've dented or scratched my guitar! The caveat being, I build my own guitars that are of the relic order. I still have a fit when I ding, dent or scratch my Vintage ES 175 or any other guitar.

Finally, will the new thin skin guitars have better tone? I reason that these guitar will have better tone but that is because of the sum total of the parts and workmanship. Are the guitars worth the cost? Yes, they have better parts, select wood, better skilled craftsman. If I had to place a numeric value on the finish surface relationship to tone I would guess it to be a value of 2% or less. Determining which surface is better is more of a subject task than one of tone chasing. Save your tone chasing for parts and workmanship and leave the finish arguments for the uninformed.


Anonymous said...

Just saw this post. While I basically agree that sonically there is little to no difference whether the finsih is nitro or poly, there were two statements that I must take exception to.

First, the idea that putting finish on the neck somehow prevents "torsion twist". The word torsion MEANS "the action of twisting or being twisted", so that term is a bit redundant. Also, the idea that .015" of lacquer or a few thousands more of poly could somehow retard a neck from twisting is silly. Twisted necks result from either poorly seasoned wood or timbers that were haphazardly selected without attention to the grain. Naturally twisted wood can be planed flat, but the spiral orientation of the wood cells will always tend to make the board curl in the direction of the twist.

Second, no finish truly prevents wood from decomposing (a good, seasoned wood being basically mummified, it will last indefinitely if not exposed to direct sunight, wind and rain). A good finish can prevent the end-grain from absorbing moisture, will repel oils and acids from the skin and will bring out the depth of the grain and any figuring in the wood.

Lastly, nitro lacquer is most DEFINITELY more labor intensive than poly. In a factory environment, a two part catylized finish can be sprayed, cured and rubbed out in a couple of days...less if it's UV cured.

Nitro must be shot, allowed 24 hours to set up (though dry to the touch in less than an hour), sanded back, allowed to shrink for a week...then the process repeated at least twice or three times more. Some pro shops might use HVLP guns with a higher solids mixture of lacquer, but even so it takes far longer and is much less forgiving in damp or cold weather. It's also VERY fussy as to any contamination on the spraying surface. The least bit of oil or God forbid silicone and you're sunk.

OK, there's my two cents. Thanks for letting me rant.

Scott said...

Excellent rant and one which I agree with. Being human and not infallible I make an occasional ;) oversight. Thanks for sharing pertinent information! Scott

Anonymous said...

I have a feeling that You're a MASH fan... :)

Hack Guitar Maker said...

Just read this. Been using nitro for 19 years but still curious. i'll continue using it

Anonymous said...

The guitar finish on my Fender electrics range from .003 - .005 thousandths of an inch (the average human hair is .004). I have guitars in polyester, polyurethane and nitrocellulose lacquer. Given similar thicknesses, I highly doubt that the type of finish has any effect on tone, and have never seen any scientific evidence that it does. If there is any difference, we're literally splitting hairs.

Scott said...

My two cents; polyester and polyurethane are rarely as thin as nitrocellulose. This article pontificates more about the repair, moreover, inability to repair polyester or polyurethane chips and cracks. As for electric guitar tone; that is a very subjective topic where finish is rarely a contributor.

Anonymous said...

I have researched the finishes on violins as well as guitars. One major factor is the amount that the finish penetrates the wood fibers before solidifying. For violins, the preferred finish was one that penetrated the least and formed a strong, elastic coating on the outside, thereby allowing the wood beneath to resonate. Penetration impedes this.

I can only extrapolate this to the finish on any wooden instrument (solid or acoustic) as having a similar influence on the tone.

My biggest regret was using nitro on a beautiful wood body without filling/sealing the wood grain first. I could hear the difference in the resonance of the instrument where the wood was noticeably less resonant and alive (compared to what it was before finishing).

As for the difference between nitro and poly, I have not made that comparison but as long as it is thin and elastic and penetrates minimally I expect similar performance.

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