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"The plain truth about Nitro" by Bruce Bennett

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  • "The plain truth about Nitro" by Bruce Bennett

    Bruce Bennett is a long time respected builder, and I thought I'd share this post from a Luthier's forum I belong to.

    There are several myths flying around about nitrocellulose lacquer guitar finishes. Many are simply inaccurate, others are outright false. let me start with the worst ones.

    1)"Nitro is made from wood so it allows the wood to breathe and resonate naturally, improving the tone."

    This statement is generally false. Nitrocellulose is made from cellulose, which is also what all plant cells are made of.
    BUT, The manufacture of nitrocellulose rarely uses cellulose, or plant cell material, from trees, but rather cotton.. which is much more easily nitrated.
    But that's not the worst part of this statement. Saying Nitrocellulose allows wood to "breathe" because it's manufactured from similar raw material, is about like saying you should be able to breathe water because it's 80% oxygen by weight and you breathe oxygen.
    Nitrocellulose lacquer paints were in fact developed by DuPont in the 1920's specifically NOT to breathe, but to be a sealant against the forces of nature for automotive applications.

    I'm not saying Nitrocellulose Lacquer finishes aren't good finishes, and aren't good for a guitar's tone, but they DON'T allow the wood to "breathe". In fact, the wood in your guitar's body stopped "breathing" within hours of the tree being cut down; it's dead now. the part of the tree we use to make guitars, was mainly the water storage and distribution system of the tree. so it NEVER breathed. it moved water up the root system through the trunk and into the leaves where the exchange of all gases actually occurred.. so it was the leaves that breathed, NEVER the wood.

    2)"Nitro takes weeks or even months to properly cure."

    This statement is utterly false. Nitrocellulose lacquers do not "cure", Curing is a chemical induced reaction (caused by a "catalyst") with a set beginning, an open time and an end ... "Cured" finishes can ever be redissolved in their original solvents.
    Nitrocellulose finishes are evaporative finishes, and CAN be redissolved in their original solvents.
    if you wish to test this, splash some lacquer thinner on your friend's mint 1957 Stratocaster. ( NO! DO NOT TRY THIS)
    Lacquers dry to the touch relatively quickly, but then it can take weeks, or even months to dry completely, leading to the misconception that they "cure".

    3)"Nitro will improve the tone of your guitar."

    This statement is misleading. If you were to take that 80's polyester finished electric guitar and spray nitrocellulose lacquer on top of it, nothing will improve whatsoever. If you were to remove the Poly finish, then yes you should hear a "change".. now is that change an "improvement"??.. only your ears can decide that.

    What makes nitro a good finish is that it is very thin, even when sprayed in multiple coats.. so it does less to get in the way of the natural vibrations of the wood, which imparts a more full tone than a thick polyester finish. BUT, make no mistake, ANY FINISH that sits on top of the wood, will alter the overall tone of the instrument.

    The simple fact is, Nitrocellulose is a good finish, and it's what was used back in the 50's and 60's.
    From the early 70's into the early 90's. thick polyester finishes were the norm, which do sound somewhat "dead" and "lifeless" when compared to older nitro finishes.
    but this is mainly due to the way these new finishes were applied.
    See the painters of that time were very familiar with Nitrocellulose and how it was normally applied.. So when their bosses told them to change over to this new poly stuff. they were most often left to their own devises to figure out how to get the same level of quality finish as the old stuff they were used to..
    and since they were used to spraying 8-12 coats of nitrocellulose.. they simply started there with the new polys, never fully understanding that the new polys were all about higher solid builds and less solvent evaporation as compared to the Nitros.

    as a general rule, Nitro has a build of 30% solids.. that's the stuff we see as the shiny finish when its all done.. and approximately 70% solvents that's the toxic stuff that evaporates into the air around us.... Polys on the other hand are almost the reserve of that.. with nearly a 70% solid build and 30% solvents.. so you can see easily how the thick finishes associated with the early polys came about.

    The other advantage that the polys had, was that they were very durable and shiny. they were also impervious to the plasticizers in your hand oils, so they were much less sticky feeling to the touch, and they didn't yellow, weather check or chip as easily as Nitrocellulose.

    Most of today's better instruments use a very thin polyurethane finish that sounds much closer to an older nitro finish than the thick polyester finishes, while still being very durable and can attain a very high gloss.

    The real truth is that the finish on an electric guitar will only play a very small role in the overall tone. The pickups, bridge, neck wood, neck thickness, nut material, body wood, body shape, string gauge and the player himself will each have at least as much to do with the tone as the finish, if not considerably more.

    What's bad about nitrocellulose lacquers is that they are very toxic, and have in fact been outlawed for use as an automotive finish throughout most, if not all, of the United States even by auto refinishers for that reason.
    They are still legal as a furniture finish, and can be bought in many states for that purpose. BUT they have been altered drastically from the original formulas. so the nitro your spraying now is not the nitro of the 1950s because that stuff was banned in 1974 by the EPA.

    There was nothing magical about Nitrocellulose finishes.

    A thin acrylic lacquer finish will be basically indistinguishable from nitro, except that it won't yellow and crack over time. and you can add up to 7% nitro back to acrylic and still get that yellowing/cracking "effect". which is what Gibson does currently, and they pay a monthly fee to do so because the EPA regs state that the current maximum allowed nitro component is only 5%

    Oil finishes such as linseed or tung oil will resonate just as much, if not more, because they don't sit "on top of the wood" like most other finishes. instead, they penetrate into the wood and mostly fill the grain up to the surface level of the wood. so in the end what you see is mostly highly polished wood, not a highly polished plastic coating.

    Thin modern polyurethane finishes do not hinder tone nearly as much as the older polyester finishes and are much, much more resistant to chipping and scratching than nitrocellulose, and in fact, when used on a guitar with a high quality neck and bridge, high quality pickups, etc ... will have a superior tone to a guitar with a nitro finish and a cheap neck, bridge and pickups.

    So all these myths about NitroCellulose finishes should be re-considered.

    Most of it is just Mystery Vibe and VooDoo generated by salemen to sell you an old "vintage" guitar verses a brand new one.

    because in the end, a 3-4 mil thick finish of Nitro doesn't sound any better than a 3-4 mil finish of poly.
    I can make this statement because I know for fact that most of the factories switched to poly based finishes years ago and never said a word..
    because ALL OF THEM use this mantra in their shops..

    "Manufacturing specifications are subject to change without notice."
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