As discussed in the companion symposium on energy efficiency, microwave furnaces for the melting and holding of metal melts are energy efficient (and environmentally green). But the major difference is the use of new types of crucibles. Gone is the necessity to use painted refractory coatings on graphite crucibles. Gone are the flaking, spalling, and recoating of graphite crucibles. By using the advantage of microwave heating, sintered ceramic crucibles are significantly less prone to problems leading to inclusions. Proper selection and handling of crucible material for the metal will permit numerous reheats. An example with aluminum alloy will be given. Microwaves can penetrate and heat various ceramics to very high temperatures. Certain ceramics, however, also do not wet or chemically react with the metal. Microwave heating, can provide a very uniform and rapid heating of certain ceramics with significantly lower thermal stress than furnaces based on infra-red. Ceramic heating cannot be accomplished by induction heating either. This also applies to the casting mold. Examples of aluminum alloy heating will be discussed.