It’s getting to that time of year when your acoustic guitar could turn on you. For no apparent reason, fret ends seem to have sharpened themselves to attack your hands, and annoying string buzzes crop up in the middle of your favorite holiday songs.
Actually there is a reason for your guitar’s change in personality. It’s dehydrated. The culprit is low relative humidity (RH) – dry air. Although we think of low-RH areas as the Rocky Mountains and the general southwest quadrant of the US, in the wintertime, the problem occurs anywhere that homes are heated. Even when the weather outside is snowy and wet, modern heating systems can dry all the moisture out of the air inside a house. And that’s bad for a guitar. The wood shrinks, and if the dehydration continues, the top will not only sink (causing string buzzes), it will crack. Low relative humidity (RH) can cause more damage to your guitar than almost any other environmental factor.
Fortunately, there’s something you can do about it. Many of these drying out effects can be prevented by simply keeping your guitar stored in its case. However, to help reverse the effects of drying, a humidifier may be used to revive the dry wood.
The type of soundhole humidifier that Gibson uses consists of a rubber hose with dozens of holes scattered over its surface and a long sponge in the center. The hose with the sponge should be run under lukewarm tap water, and wrung out completely to rid as much excess water as possible. A dry towel should then be used to completely dry the outside of the humidifier as well as any other excess moisture still contained inside it.
The humidifier is pushed through the soundhole, and into the guitar’s body, either by installing it in a sound hole cap (which may or may not be included with your humidifier) or by simply placing it between the strings to support it into place. The guitar is then placed back into its closed case, and set in a cool corner for a few days without any disturbance. This will allow the moisture from the humidifier to be absorbed back into the dried wood of the guitar body, thus restoring the wood to its natural, hydrated state.
It is a common practice to keep the humidifier moistened and left in the guitar at all times, but this can actually cause more problems in the long run. Exercise caution, and only use the humidifier when the guitar shows signs of dehydration – not as a preventative measure. Constant use of the humidifier when there is no indication of dehydration can “over-humidify” the instrument, causing it to swell and expand.
Whenever there are signs of dehydrating (for example, low string action, unexplained buzzing of the strings against the fretboard, the arch of the top starting to flatten out), steps must be taken to re-hydrate the guitar before damaging dehydration sets in (top cracks, back cracks, the top and/or the back dishing out). It is recommended that a Gibson acoustic guitar stay at approximately 35% to 40% humidity for optimal performance. A hygrometer/thermometer is recommended to measure the relative conditions surrounding the guitar.
A few thoughts to keep in mind: It is easier to re-hydrate an acoustic instrument than it is to dehydrate it. It doesn’t take a lot of water to hydrate wood, and excess water left in the humidifier can collect and leak into the guitar body, moistening the wood and causing the lacquer to lift and peel off. To determine whether your guitar is dehydrating or not, be familiar with your instrument, play it often, and know how it is supposed to feel and sound during play. Not only will this help to keep you aware of the guitar’s condition, but it will also enhance the wood itself, making it season more rapidly and giving it a wonderful new dimension of sound.