Your instrument has been built under strict climactic conditions. All woods are carefully seasoned and assembled at 40-45% humidity relative to room temperature. Your guitar is made to withstand moderate changes in humidity and temperature. However, excessive and prolonged changes in humidity or temperature may lead to damage. How you care for and protect your instrument will greatly affect its appearance, tone and longevity.
Too much or too little moisture can lead to problems, which can be avoided or minimized with some attention and care. Excessive moisture is a problem associated with summer while too little moisture or humidity is a winter problem. Your guitar will exhibit certain symptoms when exposed to major changes in humidity. Becoming familiar with these symptoms will make it easier to care for your guitar.
When the relative humidity increased beyond 55-60%, the guitar will begin to expand. Some symptoms of this are:
- The top and back will begin to swell and distort.
- All glued joints will appear more noticeable. This is most evident around the inlays.
- The finish on the top will begin to appear corrugated and the finish on the back and sides will seem to shrink into the wood pores.
- A rise in the height of the strings.
- A loss in tonal quality and a decrease in string life.
A rise in action (height of the strings) is one of the major problems observed in guitars exposed to excess humidity. The change in action is caused by a number of forces, which include top and back swelling and the expansion of the fingerboard. These changes will push the neck forward and lead to higher string height. As the instrument distorts, there will also be a loss of sound quality. All problems associated with exposure to short term high humidity should correct themselves when the instrument returns to the normal range of humidity: 40-45% relative to room temperature.
Most problems related to excess humidity can be avoided with some simple precautions:
- Never keep your guitar in a basement during periods of high humidity.
- Leave your guitar out of the case (on a guitar stand) to allow the air to circulate freely around your instrument.
- Never keep your guitar in the trunk of a parked car.
- Do not expose your instrument to direct sunlight for any length of time. A premature yellowing of the top may occur.
The winter months are associated with low relative humidity. Exposure to rates lower than 40% will result in changes to your instrument, which are more serious than problems associated with excessive humidity. As moisture in the air decreases below the normal range, your guitar will begin to shrink. Some symptoms of dryness are:
- A change in the contour of the back and the top. The slight arch can become flat or even concave.
- A line may appear around the inlays, purfling and the rosette.
- A shrinking fingerboard will lead to protruding frets.
- The finish will appear rough.
- Lowered action, which may lead to buzzing of strings against the frets.
A common winter complaint is string buzz caused by very low action. This is the result of a combination of forces. A shrinking top and back plus a shrinking fingerboard will pull the neck backwards and that will lead to a low string height. The worst problem associated with excessive and prolonged dryness is cracks in the top, which can happen when humidity drops below 30%. these cracks may appear along the center seam and on the either side of the fingerboard. This occurs in extreme situations. Another problem is lifting of the bridge. As the top shrinks, it becomes possible for the bridge to separate from the top with a shearing action. A little common sense will help to avoid most winter problems:
- Humidify your house or room is possible. Humidity should be kept at 45-50%.
- Keep your guitar in a case and use a humidity device. Be careful with this. Too much moisture will lead to summer time problems.
- Allow your guitar time in the case to warm up slowly if it has been exposed to cold.
When any of the symptoms outlined above are notice, it should be seen as a warning that humidity is not optimal and precautions should be taken. A rule of thumb to remember is: Never leave your guitar anywhere that you would not be comfortable waiting yourself.
It is not necessary to apply any oil or wax product on your fingerboard if you play the instrument regularly. The natural oils from your fingers are sufficient to lubricate the fingerboard to prevent cracking. When changing strings, it is wise to go over the fingerboard with 000 steel wool (but be careful not to scratch the finish on the top). This will remove all built-up dirt and grime. The steel wool will also polish your frets and the fingerboard making them more slippery and improving the playability of your instrument. Occasionally, clean your instrument with a slightly damp cotton cloth to remove dirt and improve the appearance of your guitar.
AND IN CLOSING
Your guitar has been constructed from various high quality seasoned woods and assembled under strict tolerances. It is a delicate instrument, which can be affected by a variety of stresses. With careful observation, common sense and care, your instrument will provide you and your listeners with a lifetime of enjoyment.