Most guitars have at least some of their components manufactured from wood. Although wood is what results from cutting down a living tree, it is far from being an inert, dead material. Much like a sponge, wood absorbs and expels moisture in reaction to changes in the humidity of its environment.

Although a finishing material is often applied to the surface of wood, the finish merely slows, rather than eliminates, the absorption and expulsion of moisture from the wood's cells. While this exchange of moisture is, in and of itself, neither good or bad, the resulting change in the dimensions of the wood caused by changes in its moisture content is of considerable concern to guitar makers and guitar owners alike.

Changes in humidity can cause a wide range of symptoms from deadened tone, changes in string height, minor string buzzes and lifted frets to loose braces and major cracks in fingerboards, tops, backs and sides. In this article, I will examine how you can reduce the effects of changing humidity on wooden guitars.

To avoid problems you should use one of these:
Acoustic Guitar Humidifier