One important yet little-understood factor in caring for your acoustic guitar is humidity. Either too much or too little moisture in the air can have a nasty effect on the wood, tone and life of the instrument.

Richard Hoover, the man who founded the Santa Cruz guitar company recounts how he once visited a now-defunct Chicago music shop and saw a glass-encased room with several Guild acoustic guitars inside. For some reason, the humidity in the room was so high there was condensation (water droplets) on the glass. All the guitars on display in the room were saturated and warped.

This warping of the wood is simple to explain: wood is porous and will absorb water that is floating in the air (humidity). The water, once absorbed into the wood, causes wood to swell. Swollen wood pushes in all directions and eventually will warp and crack if not de-humidified.

The above is an extreme example. Some humidity is good for your guitar, but too much is very, very bad. It's a fact of life for guitar owners that the environment plays some role in the guitar's sound and condition.

But what about when you live in an area where the temperature and humidity vary wildly? Are there any tools you can use to measure humidity and act accordingly, either by running a room humidifier or de-humidifier in the room where the guitars are stored?

Nick Ellingsworth, product manager at Washburn Guitars, had some thoughts on humidity and the seasons.

"I would say that it's not so important what time of year it is. Even during the summer you can have hot dry days or dry conditions in your home due to air conditioning" says Ellingsworth. "What is important is that you have a hygrometer so you can measure the level of humidity in the guitar case."

The hygrometer is an instrument that measures humidity and you can usually find one at any electronics store (such as Radio Shack). The hygrometer is small enough to measure the humidity level of the air inside of a guitar through its soundhole. This means it can tell you if humidity treatment is appropriate for the guitar's inside or outside.

"If the humidity is above 40 percent inside the case, you don't need a humidifier - and should remove it if you are running one since too much humidity can cause swelling," says Ellingsworth. "If the humidity is below 40 percent, you should be using a humidifier."

Ellingsworth notes that the optimum humidity for a guitar is between 45 and 55 percent with a temperature between 65 and 80 degrees.

Hoover, on his Santa Cruz Guitar website, notes that the humidity conditions humans find most comfortable are also the best for a solid wood instrument. He also suggests buying a hygrometer for the reason that it is imperative to know what you are measuring. A hygrometer measures the amount of "relative humidity" - the amount of moisture "in the air relative to maximum amount of moisture air can hold before it reaches the saturation point."

The higher the air temperature, the greater the air's ability to hold water, hence the tendency to see more warping during summer months.

Because of the swelling and contraction action introduced by moisture interacting with wood, instrument adjustment may be called for due to inappropriate humidity levels. In some parts of the country it may be advisable to have your acoustic guitar's neck regularly adjusted by a professional as the seasons change from hot to cold, from wet to dry.

For more detailed information log on to the Santa Cruz Guitar company's website.