Guild Acoustic guitar Owner's Manual & Warranty page 6

Conversely, if you live in or travel with your guitar
to a drier climate (either hot or cold), there is another
danger—in areas of low humidity, the evaporation of
moisture in the wood can cause shrinkage and
cracking, no matter how long the wood may have
been previously aged. This also can cause the top and
back to shrink, making the string action low.
The collective experience of all major guitar
manufacturers today has demonstrated that the ideal
temperature to preserve the integrity of solid wood
acoustic guitars is room temperature, which is about
70 degrees F (20.5 C). The ideal humidity is about
40% to 50%.
In winter, forced air systems used to heat most
homes can drive temperatures up and humidity levels
dangerously low for guitars. A good measure of protec-
tion against your guitar drying out is to use a room
humidifier.
When the instrument is not in use, we recommend
that you keep it in its case and use one of the small
guitar humidifiers such as "Dampit," available from
many instrument dealers. Do not leave the guitar out
for long periods near a heating vent, radiator or in
direct sunlight near a window.
Do not leave your guitar in the trunk of a car for
long periods and keep it away from excessive heat
and cold. Please note: Damage caused to the guitar
as the result of exposure to temperature or
humidity changes will not be covered under the
Guild warranty.
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