Dealing with Humidity

“Acoustic owners need to care for their delicate wooden instruments during the cold, dry months. Paying attention to humidity won’t hurt electric owners either, so here’s the skinny on chapped lips and cracked guitars.

In the humid summertime, guitars may suffer from becoming too wet, getting such symptoms as higher action (due to a more swollen top, which occasionally causes a bridge to loosen as well) and a flat, “tubby” sound. Solve the high-action problem by having a lower “summer saddle” made for your guitar. The tubby sound goes away by itself in the fall, or whenever you have three or four nice, dry summer days in a row. Summer conditions aren’t as dangerous as winter ones, however, since the wood seldom cracks due to over-humidification.

Low humidity occurs in the winter in most areas, and all year long in some desert and mountain states. Heating your home, especially with forced air, adds to the dryness problem. When a solid-wood guitar dries out, the wood shrinks across the grain. The fingerboard shrinks, and the fret ends poke out from the sides. Tops flatten out or cave in, lowering the bridge and allowing the strings to buzz on the frets. The back may also flatten, and glue joints anywhere can come apart. If the wood dries too rapidly, the finish may check. In extreme cases, braces can come loose and the back, sides, and especially the top can crack. Most of these troubles can be avoided by adding moisture to the guitar’s environment.

Use a hygrometer to measure your home’s relative humidity; combination thermometer/hygrometers aren’t expensive. If you’re fortunate enough to have a furnace with a whole-house humidifier, use it; if you don’t, consider having one installed. Check out the portable room humidifiers available through Sears and other companies. A natural approach is to leave bowls of water to evaporate on wood stoves and heater grates. Any of these measures will help, but they may not be sufficient protection against the dreaded crack monster.

Lately, soundhole humidifiers have gained popularity with many players and manufacturers. Two companies, Dampit and Ontek, manufacture soundhole humidifiers that sell for about $12.00. Simply put, these devices are dipped in water and then mounted in the soundhole when the guitar’s not in use, and they slowly distribute moisture inside the guitar body. These humidifiers have soundhole covers that must be used to work properly. With the proper use of these humidifiers in the dry season and possibly a lower saddle in the wet season, your guitar should play consistently all year round. I asked acoustic experts Dick Boak from Martin, Bruce Ross at Santa Cruz Guitar Co., and Bob Taylor from Taylor Guitars for their thoughts on humidity and soundhole humidifiers:

Bruce: “Humidity control is most crucial to newer guitars. Once a guitar makes it through its first four seasons, it comes to terms with itself. Use the soundhole humidifier with care. I’ve seen them harm guitars, too, from overwetting , which lets water drip inside.”

Bob: “Lack of humidity control is the single source for over 90% of guitar problems. How you wax, clean, play, tote, strum, strap, oil, or loan a guitar is your business. These things don’t matter a whole lot – the guitar will stand up to them. But when it comes to humidity, a little attention each time you play your guitar will make it last forever.”

Dick: “Guitars sound terrible when they’re full of moisture. But sometimes humidifiers are necessary – more so with newer guitars – and we sell both the Ontek and Dampit here at Martin. New guitars need special treatment for the first few years. Mostly watch the heat when it first comes on in the fall – don’t ‘force dry’ your guitar. If all the drying happens in one day, you’re in trouble. Keeping it in the case when you’re not playing is a big help – with or without a humidifier.”

Bob: “Try to keep a new guitar from any real shock (whether dry or wet) for three or four years. Lots of unnecessary and wasteful repair work is avoided by using a soundhole humidifier during the dry months. At Taylor, we include Dampit with each guitar because it works. The Dampit is almost useless without the soundhole cover, but magic with the cover. We know of repair shops that use Dampit to fix guitars!”

Don’t oversoak the humidifier; be sure to squeeze it out enough. Check the guitar’s progress daily. Let your guitar tell you when it needs moisture. If the action’s low and buzzy, and the top shows little or no arch, then you probably need to use a humidifier. If you’re using Dampit or Ontek for the first time on a guitar that’s already dried out, expect to refill it after the first day – your guitar’s thirsty. Keep your axe in the case during weather extremes, and learn to “read” your guitar – it’s a great humidity gauge. When needed, use a humidifier from fall till spring. Soundhole humidifiers are inconvenient, but they’re better than facing major repairs.

No system is perfect, especially when dealing with delicate wooden instruments that exist in a variety of climates. What’s good for my guitar may not be good for yours, but many guitars will benefit from the use of a soundhole humidifier.”

- from the Guitar Player Repair Guide