Perhaps the most misunderstood problem with wooden clarinets is cracking. It is impossible to guarantee that wood will not crack. Despite its great density, grenadilla, like any other wood, absorbs and releases moisture. It is hygroscopic. Moisture will be absorbed from the players breath and from the resulting condensation in the tube as well as from the atmosphere itself. The humidity inside the instrument will be close to 100% when played. When moisture is absorbed or released too rapidly or unevenly, internal stresses are set up within the wood. If these stresses are too great the instrument can crack.
If that happens the crack can be nicely repaired without reducing the quality of the instrument. Dont wax or oil the wood when that happens. The tone-hole needs to be replaced. If this is done correctly everything will be fine.
Dont get the instrument pinned under any circumstances!!!
(Read also: Crack pinning )
Unfortunately, this obsolete and destructive technique can still be found.