Apparatus and a method for processing a ceramic material includes placing the ceramic material in a microwave heating apparatus having a microwave cavity; subjecting the ceramic material to a combination of microwave radiation and conventional heat; and controlling the uniformity of the processing of the ceramic material so as to avoid deformations and cracking by applying the microwave radiation to the ceramic material through at least one branched slotted waveguide which substantially uniformly distributes the microwave radiation throughout the microwave cavity.