Transmute Metal to Wood

The transmute metal to wood spell allows the druid casting it to change an object from metal to wood. 

The volume of metal is equal to a maximum weight of 80 gold pieces per level of experience. Magical objects of metal are only 10% likely to be affected by the spell. 

Note that even a dispel magic spell will not reverse the spell effects. Thus, a metal door changed to wood would be forevermore a wooden door.