Higher-end guitars are typically made of thin strips of glued wood and are very much affected by temperature and humidity. The temperature of the room can affect how much moisture the air can hold, so both factors will impact the wood because wood is considered “hygroscopic”, meaning it takes in AND gives off water.
If the room humidity is high and the guitar absorbs a lot of moisture, it can expand and swell, which will change the tone and playability. Conversely, if the environment is too dry and devoid of humidity, your guitar can also be detrimentally impacted. It may experience shrinking, cracking, poor tone or intonation issues.
When guitars are built, they’re assembled in environments that generally have consistent temperatures and humidity; however, when a guitar leaves the shop, obviously these factors change. The onus then moves to the instrument retailer and the eventual owner to keep the guitar properly humidified so it continues playing and sounding good.
Guitar humidifiers can help avoid minimize these threats to your prized instruments. There’s 3 types of humidifiers:
- Sound Hole Humidifiers: these either cover the sound hole of your guitar or sit between the strings in the sound hole.
- Guitar Case Humidifiers: these sit inside the case, usually under the headstock, to keep the entire case regulated at a constant humidity.
- Room Humidifiers: these keep the entire room regulated and are very useful if you wish to keep your guitars out of their cases and hanging on the wall or resting in a stand.
Guitar humidifiers don’t necessarily need to be re-wet on a daily basis. Depending on the season, and the local climate, you may only need to re-wet the humidifier maybe every one to two weeks.
To make a long story short, ideally, you’d like to have the environment to be consistently at or around 75 degrees. And a relative humidity level of about 50%. Do what you can to avoid extreme changes in temperature and humidity.