Whether or not you’re a guitarist, you’ve probably at least once found yourself wondering why a musician who’s freakin’ loaded would play a beat-up old guitar that’s falling apart when they could easily afford 100 new ones.
We’re looking at you, Willie Nelson.
Aside from aesthetics (some people think beat-up stuff looks cool) and familiarity—every guitar is different, and players grow attached to them almost like family members—there’s another reason: instruments sound better as the wood they’re made from ages.
Well, technically, just “different”, but just about any guitarist you ask will say it’s “better”.
What happens when wood ages?
According to luthier (instrument builder) Alan Carruth, wood consists mainly of cellulose, lignin, and hemicellulose, and all wood gradually loses hemicellulose—a soluble polysaccharide—to evaporation over a long period of time.
As this happens, the wood loses some weight, but remains just as stiff, allowing it to continue to support the weight of strings. With less mass to have to vibrate, the guitar’s woods vibrate more freely, making the instrument louder and allowing previously dampened frequencies to resonate.
The crystallization of sap inside the wood over time also contributes to the wood’s stiffness.
Likewise, lignin degrades as spruce (the wood most commonly used for a guitar’s top) is exposed to sunlight. Most notably, this results in a usually white wood taking on a yellow or orange hue that tends to be considered more aesthetically pleasing. Of course, degradation of lignin means a change in the wood’s physical structure as well, meaning that it contributes to the sonic side effects of aging.
Can this be done artificially?
While guitar manufacturers have long been selling guitars with aging toners to make their instruments look like they’ve seen more years than they really have, these only affect a guitar’s aesthetics. More recently, however, manufacturers have begun to treat woods with a process called torrefaction.
Wood destined to be used in guitar building is usually kiln-dried to a moisture level of about 6-10%. Usually, that is all that’s done, but torrefied wood is subsequently “cooked” at even higher temperatures in an oxygen-controlled environment until the wood’s moisture level reaches zero percent. Then, it’s removed from the kiln and brought back up to 3-6% humidity.
All of this makes for a lighter, stiffer, more resonant piece of lumber, with a bit of a darkened, amber hue—the rapid heating of the wood and evaporation of moisture causes the sap to crystalize and hemicellulose to degrade more quickly.
Whether accomplished artificially or naturally, the aging of wood affects the sound of an instrument, and most musicians hear it as a good effect.
Just don’t expect this guitar to improve with age.
Feature Image: Thinkstock