The dielectric method is used when heating electrically insulating or poorly conducting materials. Common applications are the drying of wood and drying glued joints in wood. The method is also used for heating various types of plastic and for drying and vulcanising rubber. In certain materials as, for example, wood, it is the ions that begin to move (oscillate) in step with the frequency of the electric field. In other materials, e.g. plastic and rubber, in which there are few ions, it is the molecules that start to oscillate instead. A characteristic of the dielectric method is that the amount of heat can be controlled very accurately and also concentrated in localised areas of the material being heated.