Wood is constantly drying out from the time it is cut. As wood ages the wood fibers crystallize, the pith wood gets softer and the growth rings get harder. It is advantageous to have your instrument dry out as slowly as possible. It is important that you keep the natural moisture of the wood high as long as possible. Once wood looses its natural moisture it doesn’t get it back. To do this, keep a wet sponge or a humidor inside your guitar case. When using a sponge, place moistened sponge in a plastic bag and poke holes in it. It is amazing how much moisture a guitar will absorb. Avoid storing your guitar in hot attics, trunks of cars, near heaters or furnace vents. Most repairs to acoustic guitars is from the guitar drying out too rapidly.