Microwaves are a form of electromagnetic radiation. Their great advantage is their ability to transfer heat without contact. The materials to be treated absorb the radiation through their surfaces, regardless of the flow of heat, so that they are evenly heated. In contrast to conventional drying processes, microwaves have a considerably greater penetration depth. In addition, they only apply energy to the component which is to be hardened and heat without inertia, so that the actual oven remains cold. This results in a further advantage: Heating and cooling times, as well as the time for the actual hardening process are reduced. As well as this, the process is extremely energy-efficient.