Humidity Effects on an Acoustic Guitar

PROTECT YOUR GUITAR FROM EXCESSIVE DRY and WET or TEMPERATURE EXTREMES

Robson Acoustic Guitar shop is climate controlled, with Relative Humidity maintained between 40-45% and temperature at or near 70F. The design of the guitar provides a reasonable ability to respond to changing humidity, but long term dryness or excessive moisture can cause irreparable damage. If you cannot humidify the air in your home, then consider proper use of a GUITAR HUMIDIFIER in the case, these are sold by most reputable music stores, but must be used per the Mfg specific instructions. Humidity controlled display cases are also available on Web.
Also, PROTECT YOUR GUITAR FROM TEMPERATURE SHOCK and EXCESSIVE HEAT. Similar to humidity extremes, very high temperatures will also damage instruments. Please read the “CARE INSTRUCTIONS” provided with your Robson Acoustic Guitar. Your Guitar Case is your 1st defense.

RELATIVE HUMIDITY is measured with a Hygrometer (humidity gauge), available from most hardware stores, Walmart, on-line, etc. Some designed for for your case, but certainly your home. Be aware, it is possible in a large room or space to have different levels of Relative Humidity at ends of the room, especially if no air movement exists. Below is a chart to help understand ranges and effects.

% RH Comments / Actions
85-95% DANGER – Wow! Much too humid for your guitar. Swelling is causing very high string action, glue joints are being stressed, avoid this in consideration of your guitar, if you do not dehumidify, bad things will happen to the guitar.
75-80% Still too humid, tolerable for short time spans (few hours), but realize the soundboard is swelling, moving the bridge you’ll notice higher action (string height above the frets), harder to play. Take action to reduce humidity in the short term.
60-70% 60% is pretty tolerable, but above this, say up to 75% the guitar will be moving, swelling and affecting the action.
40-50% 40-50% is a good range with 45% near perfect for long term storage.
35% 35% can be tolerated, but realize it is time to humidify, the wood is starting to dry out. You may notice the soundboard starting to sink in (top should be a slightly raised with arch across the top near bridge). May be ok for couple days, but try to keep the Guitar in a case when not being play, recommended to use a good instrument humidifier (readily avaialble at most reputable music stores).
30% Now we’re getting too low, take action to humidify the guitar. You’ll notice that the action is getting pretty low, may hear buzzing of strings, as the neck wood shrinks, the metal frets may start to stick out (you will definitely feel that). ACTION: Store guitar in the case, with a good Guitar Humidifier when it is not being played. Humidify the room too if possible..
20-25% DANGER: Be worried, you have reason to! Left at this dryness may cause irreputable damage. The moisture is rapidly leaving the tone woods and neck, the back and top will draw in (toward inside) and cracking longwise may be observed. Strings are almost sitting on the fret board, and the frets are protruding … LOW HUMIDITY IS WORST THAN HIGHER, AS THE THE GUITAR WILL QUICKLY DETERIOATE, CRACKING, BRACING BROKEN LOOSE OR DAMAGE AT THE BINDING, BACK, TOP, BRIDGE AND NECK.