Have you noticed that some days your acoustic guitar sounds brilliant and then others it sounds crap? Well maybe your ears are not playing tricks on you but are detecting the way your guitar reacts to changing atmospheric conditions.
The fact is your acoustic guitar sounds its best when the body has just the right amount of humidity. Proper humidity levels will also prolong the life of your instrument. Ironically your expensive hand made instrument with a solid top is more prone to changing climatic conditions than a mass produced laminated top instrument.
The ideal humidity level for a guitar is somewhere between 45-55% relative humidity and you can tell if the humidity level is causing problems for your guitar by observing these signs:
Sharp Fret EndsLoss of moisture can often cause the fingerboard to shrink leaving the frets slightly protruding from the fretboard.
Lower String ActionLack of moisture can cause the fingerboard extension area to sink, creating problems where the neck and the body join. The top of the guitar may also dries out, resulting in it sinking, producing buzzing on the frets because of the lower action.
Cracks / Opening SeamsMoisture loss causes an instruments timber to dry out and shrink, resulting in cracks which if not attended to can eventually spread open and result in costly repair work. Most luthiers keep their workshops between 25 and 45% while manufacturing, therefore the ideal humidity level for your instrument would be around 45%.
Raised GrainThis problem can be detected by running your finger across the finish. If you notice rippling because of the raised grain then action needs to be taken before cracks start to appear and things deteriorate.
A hot car.
Near heat sources such as wood stoves, heaters and fireplaces.
Damp basements and hot attics.
The air is typically drier during the winter because cold air holds less moisture than warm air. This plus the fact that room heating removes moisture from the air means that a humidifier will be needed more often under these conditions.
It must also be noted that your geographical location will often be the significant factor in deciding when to use a humidifier.
As a rule any humidity reading below 45% will mean you should start using your humidifier.
Always check the moisture level in your humidifier particularly if the humidity level drops to 20% or lower.
Always store your guitar in a head shell case. Not only will it protect it from accidental damage but will lessen the effect of atmospheric changes. A word of warning about the little silica Gel packets that case manufacturers often put in their cases. Take them out and put them aside just in case you encounter a situation of high humidity and you need to reduce the humidity level.
Avoid wide rapid temperature changes. If you must bring your guitar from a cold environment into a heated room leave it in its case to let it slowly acclimatise to the warmer room.
If possible store your guitar in an air-conditioned room to keep it from loosing its clear, crisp sound.