The climate in Portland is usually a good for stringed instruments with one exception: extended periods of several days or more, during the winter months, of sunny days that are below freezing, especially when our weather is coming from the eastern desert areas. The humidity can then become dangerously low in most heated spaces.
Fine guitars are made of thin pieces of solid wood that are glued together. They are directly affected by humidity and temperature.
Humidity is the amount of water vapor or moisture in the air. Temperature affects the amount of moisture that air can hold. Both of these factors affect wood because it is naturally "hygroscopic". This means that it takes on and gives off water. Therein lies the challenge.
A guitar that absorbs too much moisture, through high humidity, expands and swells. This distorts the geometry of the guitar and, consequently, its tone and playability. Add high temperature, and humidity can weaken glue joints and even cause them to fail. With prolonged exposure, the glue under the bridge will weaken, allowing the bridge to pull off.
Telltale signs of a "wet" guitar:
• High action
Overly dry conditions, or lack of sufficient humidity, can be equally detrimental to your guitar, causing the wood to shrink and crack. It can also cause poor tone and improper intonation. In dry regions (mountainous or desert areas) or northern climates, where heated air is common in winter, simple guitar humidifiers may not be sufficient. Room or household humidifiers may be necessary to maintain a proper environment.
Telltale signs of a "dry" guitar:
• Lowered action
Gradual changes in humidity and temperature will generally not harm a well-made guitar. At Collings, we build and acclimate our guitars in an environment of 49% relative humidity and a temperature of 75 degrees. So if you keep guitar pretty close to these ranges, you should have no problems.
• Keep your guitar in its case when you’re not playing it. Collings guitar cases are virtually air tight – and it’s a lot easier to control humidity in a smaller volume of air.
Many fine guitars are finished with multiple coats of high-grade lacquer, hand-sanded between applications to bring out a deep shine. The resultant finish is thin, durable and acoustically compatible. The best way to preserve this finish is to keep it clean – wiping off perspiration and fingerprints with a soft, damp (not wet) cloth. Old, soft cotton baby diapers make excellent guitar cleaning cloths. While there are many commercial guitar cleaners available, we feel that a rag slightly dampened with plain tap water and thoroughly wrung out will remove most dirt. Then buff with dry clean cloth. If you must use commercial products, avoid those with solvents, silicones or abrasives. Remember: polishing is not cleaning. Polishes remove finish along with dirt. Fingerboards can occasionally dry out, but require only a very small amount of boiled linseed oil (thoroughly buffed) to restore. Less is always best.
Thanks to Collings Guitar http://www.collingsguitars.com/care.html