Article by By Richard Johnston
Most guitarists and luthiers agree that guitars “open up” and change as they’re played. Here are some of the things that happen to a guitar as it ages.
From new and pristine to vintage and broken-in: A recent Martin HD-28 and a 1956 D-28.
“It’ll sound even better when it opens up.” Almost anyone shopping for a new acoustic guitar, or even just talking about them, has heard that line or a variant with roughly the same meaning. Whether the key phrase is “breaks in” or something more colorful, like “when she gets used to bein’ a geetar,” the point is always the same: when you’re playing a new guitar you can count on it sounding better in the future. This isn’t a new concept, or even leftover guitar-karma newspeak from the ’60s; statements about wooden musical instruments improving with age appear in the earliest printed catalogs of American guitar manufacturers from the late 1800s. But what really happens, and why? Is it merely age that makes a guitar sound better, is it being played that makes the difference, or is it both? There’s far more speculation about all of this than there is scientific fact and serious research, but this article will explore what is known, what’s widely suspected, and the common mythology behind why many players feel their guitar sounds better with every passing year.
Wood and Water
Most guitar bodies aren’t finished inside, allowing moisture to easily enter the wood.
It’s hard to quantify what happens to a guitar when it is played, but there are a few reliable facts about how guitars age. With few exceptions, virtually all guitar bodies made of solid wood are unfinished on the inside, regardless of how the exterior surfaces are treated. And of course there’s that big soundhole in the top (or two smaller f-holes on an archtop), making your guitar’s sound chamber much like a room with a good-size window that’s open year-round. So, even if the instrument has a thick polyester finish that would hold up to a skateboard’s wheels, the interior of an acoustic guitar takes on moisture when exposed to high humidity and then loses it again when exposed to drier air, in delayed sync with the climate around it. This process of “breathing” continues even in older instruments, but the guitar-building community has learned from years of experience that new guitars react more dramatically to changes in their environment when compared to an older instrument. Because guitar woods are so thin (usually less than 1/8-inch for flattop models), it’s easy to imagine that most of the woods in a guitar body, not just the interior surfaces, are “aging” rather quickly, primarily from the inside out.
The wood is not the only part of a guitar that continues to age after it’s completed, strung, and tuned. Many new guitars are still finished with nitrocellulose lacquer, a durable, fast-drying coating developed almost a century ago. Even after lacquer has dried enough to be buffed to a mirror-like surface, it continues to harden and contract over time, partly from the evaporation of the solvents that held it in a liquid solution so it could be flowed onto the guitar’s surface. Even the more modern catalyzed finishes, which harden by chemical reaction rather than by evaporation of solvents, change over long periods of time, although not as dramatically as nitrocellulose lacquer does. Even when your guitar is brand new, don’t let its hard, shiny exterior surfaces fool you, for while we often think of modern guitar finishes as being a sealant against just about anything but harsh chemicals, they are not. True, water will run off the surface, often without leaving a sign, but water vapor still gets through to the wood beneath the finish eventually. As finishes like nitrocellulose lacquer age and begin to break down, they usually become even more porous.
From Tree to Instrument
Lumber is seasoned for extended periods before being used in guitar restoration (shown at Taylor Guitars).
To more fully understand how a guitar ages, it helps to remember how it went together in the first place. Though the thinly sliced wooden boards used to make a guitar’s sound chamber—the top, back, and sides—may have been dried from a few months to several years, once most guitar makers start to put a guitar body together, that part of the building process is completed rather quickly. Obviously, the sides of the guitar get dramatically manipulated by steaming and bending, but the top and back are tweaked in the process as well. Virtually all modern flattop steel-string guitars have tops that aren’t really flat at all, but are slightly domed by arched bracing glued to the underside. Guitar backs have an even more pronounced convex shape, also caused by the arched bracing visible when you look through the soundhole. This means that in just a few days, or at most a few weeks, a little stack of flat pieces of guitar wood is transformed into a box with curvilinear sides and an arched top and back, all held together with glue.
Some builders feel that the hardness of hide glue results in a better-sounding guitar.
If you look inside a guitar, the importance of the adhesives used to hold all those pieces together is obvious. The book-matched halves of the top and back are glued together, the all-important braces are glued to those same surfaces, and the bridge, which transmits the vibrating energy of the strings to the soundboard, is also anchored with glue. (The bridge is also a structural brace; it just happens to be the only one glued to the exterior of the guitar body.) The modern adhesives used by guitar manufacturers set rather quickly, which allows for faster assembly, but most of these glues continue to harden somewhat over an extended period. Since such adhesives are the bond between pieces of wood that vibrate as the guitar is played, they also have at least a small role in the instrument’s overall response. Is the glue holding together a 20-year-old guitar significantly harder or different than the same glue in a guitar half that age? Probably not. In fact, all of the differences discussed here are most noticeable when comparing brand-new instruments to older examples. A one-year-old guitar will have changed in comparison to an identical model just completed, but a 20-year-old guitar won’t be 20 times as different.
When it comes to identifying how guitars improve as a result of being played, it’s much more difficult to determine what happens to an instrument and how much it changes. There’s no doubt that there is a lot of tension on the soundboard, and on all the other parts of the body, when a guitar’s strings are tuned to pitch. Even a set of light-gauge bronze strings, tuned to standard pitch, exerts more than 150 pounds of “pull” between the top and neck of a guitar, and the tension of a medium-gauge set is roughly equivalent to adding a seventh string to a light-gauge set. With 150 pounds of string tension vibrating as you play, it’s no wonder you can often feel your whole guitar, not just the soundboard, humming along. But is it the effect of the string tension, or the vibrations that result from those strings being plucked and strummed, that makes the difference between the sound of a brand-new guitar and an older one? Guitarists sometimes talk about “warming up” a guitar by playing it, suggesting that once the guitar body has been resonating for a few minutes, it begins resonating better, or more musically, than it did when it was first pulled from its case. But is the guitar actually warming up or is the player making subtle, subconscious adjustments in his or her playing that results in a perception of improved tone?
This is why testimonials about how much better guitars sound as a result of use, whether it be a few minutes or hundreds of hours, can get tricky. Part of the problem is that most guitars being tested are not quite the same, even when they’re from the same manufacturer. Even something as seemingly insignificant as neck width or string action can make real-time comparisons between two almost-alike guitars problematic, and this is especially true when one of the instruments is older than the other. Comparing the same guitar in a “before and after” test is hampered by the fact that humans have a proven difficulty remembering subtleties in tone over long periods of time. Most audiophiles agree that to accurately compare speakers, for example, the A versus B comparisons have to take place within seconds.
Even more troubling is that most testimonials comparing guitar tone result from tests where the player knows which guitar he is playing, and thus knows which guitar should sound better based on conventional wisdom. Fortunately, there are a few examples of comparisons of two nearly identical guitars, built at the same time, where one has spent years under the bed or in the closet while its sibling was hauled onto the world’s stages and into countless hours of solo practice, group rehearsals, and jam sessions. In one such example observed in the shop I co-own—Gryphon Stringed Instruments, in Palo Alto, California—two 1983 Martin dreadnoughts that sounded very similar as brand-new guitars have been occasionally reunited. When both the heavily played guitar and its rarely played littermate are strung with the same brand of new strings and tested by a player who is not allowed to see which guitar has the nicks and dings, the two instruments still sound nearly identical to listeners. While this is hardly a scientific test, it does suggest that an acoustic guitar that has spent 25 years or more in the closet is not necessarily going to be a tonal slacker until someone finally puts a few hundred hours of playing on its strumometer.
The Vintage Temptation
For guitar makers, the astronomical prices currently paid for some guitars made three-quarters of a century ago make building, and marketing, new instruments that are “just like the old ones” an obvious goal. One of the bonuses of this trend is that we now know a lot more about those “golden age” instruments than we did 20 years ago. And while the new reissues may not be exactly the same as the originals, they are often close enough that when direct comparisons between the sound of new and old take place, the results are often surprising. True, the older guitars usually win out, but in blindfold tests here at Gryphon, listeners rank the new guitars much higher than they do when they know that instrument A is worth more than ten times as much as instrument B. This is partly because contemporary guitar makers are now using the same glues, neck construction, and bracing patterns as was used when constructing the old guitars, not just the same species of wood worked to the same thickness. When an excellent-sounding reissue is heard alongside a not-so-exceptional vintage example of the same iconic model, it’s obvious that age and lots of use are no guarantees that any one particular guitar will have great tone.
There is no question that stringed instruments change as they’re aging and are getting played. On some instruments, the changes people detect are dramatic, while on others they’re more subtle, making it difficult to predict the sound a new guitar will deliver in the future. For these reasons, it’s best to not count on specific tonal improvements when purchasing a new guitar, but rather to choose one that sounds great to you now; think of anything else as icing on the cake!
Richard Johnston is cofounder of Gryphon Stringed Instruments and is an Acoustic Guitar contributing editor.
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