Living in South Florida has many advantages. Lots of sunshine, beaches to lie on, but the greatest disadvantage is the humidity. It really can wear you out. The relative humidity typically ranges from 49% (comfortable) to 92% (very humid) over the course of the year, rarely dropping below 33% (comfortable) and reaching as high as 100%. That. Is. Humid. So lets talk about some extremes in humidity and its effects on acoustic guitars
Heat causes things to dry up. With drying there is shrinking. With shrinking comes cracking. This is the basic process of drying wood. Now imagine that nice $1300 Martin Acoustic Guitar doing this. WTF? It can happen. Here are a couple of examples how this can happen:
- Leaving the instrument in direct sunlight
- Placing the instrument near a fireplace, stove, or heater
- Storage in the attic
- Leaving the instrument in a car for any or extended periods of time (Temperature of a car can reach 180-200+ degrees in only a couple hours!)
Repairs from this kind can cost several hundred to thousands of dollars, depending on the instrument and the extent of damage. Heat is used to loosen glue joints on guitars for repair. Excessive heat can soften glue joints and allow them to loosen or slip. One of the most common problems on flattop guitars as a result of excessive heat is a sliding bridge. Once heated, the bridge can lift or actually begin to slide towards the sound hole. While this is easily spotted, there are other areas of the instrument that can be adversely affected that are not as easy to spot. Frets, neck joints, braces and literally anywhere glue is used can be affected by heat.
Florida residents do not see too much cold weather if any. There are times when traveling you could experience some very cold weather. One extreme in the cold in regards to acoustic guitars is cracking of the finish or finish checkering.
Finish checking and crazing are often the result of severe temperature shock caused by taking a very cold instrument into a very warm environment suddenly. The ending results can look like spider web like cracking on the surface. Refinishing the guitar is the only solution and can cause more harm if you are not experienced in doing this particular repair. When instruments are shipped or transported during the winter it is highly advisable to let the instrument slowly warm up to room temperature before removing it from the shipping carton or case to prevent this kind of damage.
With the cold comes a lack of humidity. It is very important in the drier times of the year to make sure that the instruments humidity is maintained around 45%. To prevent dryness, a humidor or humidifier can be used to control moisture.
What are the signs of a dry Guitar?
Wood Grain Prominent
The wood grain is clearly felt and is prominent to look and touch. The soft wood between the darker grain lines has lost its moisture and the grain now stands prominent. Once this becomes severe, cracks are usually imminent. This may be your last chance to avoid cracks.
Sharp Fret Ends
The fingerboard shrinks due to the loss of moisture but obviously the metal fret wire does not. The frets are now wider than the fingerboard and the sharp ends can become exposed. This is really noticeable on unbound fingerboards. This is called fret spouting. This can be fixed by filing down the edges. Check the link to see how this can be done.
Lower Action / String Height
The top has begun to flatten out as it looses moisture and the action is lowered as a result. The fingerboard extension (portion of the fingerboard which is glued directly to the top) may also sink a bit causing a bend in the area where the neck and body join.
The wood should be completely flat and smooth at all times. If it’s starting to concave, there could be serious problems. If you’ve gotten to this point without a crack you are very lucky. Still a problem nonetheless.
Cracks / Opening Seams
After severe moisture loss, the instruments wood panels begin to shrink. Eventually this can prove too stressful for the wood and it cracks. If left unattended these cracks can spread open and create even more costly and highly visible repairs.
Where to start to controlling humidity
Humidity can be controlled by:
- Storing the instrument in its case
- Using a room humidifier
- Install a hygrometer to read humidity in your home
- Install a sound hole humidifier
- Keep humidifiers filled
It is best to use a room humidifier in conjunction with an instrument humidifier. If the air is very dry, a small sponge may not be enough. For those with many instruments, refilling instrument humidifiers could be pain in the butt, but it is easier to control the room’s humidity with a room humidifier. It’s important to use a hygrometer to determine the humidity levels in your home. While low humidity is very common in the winter in Northern States, not all areas share the same problems. In the summer humidity levels generally stay around 50% and above in some places, eliminating the need for humidifiers during those times. Instruments that find their home on islands and states where humidity is very high can also be affected by the high humidity and rather than needing additional moisture, they need less.
Storing your instrument
It is usually best to store the instrument in the case. Not only does it protect it from damage, the case can offer more protection from severe and sudden environmental changes.
Dripping of Water
Anytime a humidifier is used with an instrument it is essential that water does not drip into the instrument. If enough water is spilled inside, the wood can swell and create finish damage or haze. Also keep in mind that, depending on your location, humidity levels may increase during the summer and eliminate the need for a humidifier as stated earlier.
Silica Gel Packets: Cheap Humidity Control
The purpose of the silica gel pack is to absorb moisture and keep everything dry. Unless you are living in a humid area these are not necessary and can do harm. This is the reason manufacturers place them in the instrument cases.
Its important to maintain humidity levels around 45-55%. Wood will try to equalize to the surrounding air, in temperature and humidity. If wood becomes too moist it will swell; on the other hand, if wood gives up it’s moisture, it will shrink. All are physical characteristics of wood. Be sure to store instruments in their case and this will prevent severe temperature changes and help acclimate to colder conditions. This will keep that Martin in tiptop shape for years.