Place 1/2" of activated carbon in the container. Place greenware on the carbon and cover over with 1/2" of activated carbon. Place greenware in a single layer only. Fire according to the guidelines included with your metal clay. It is important not to place too much carbon over the wares. Too much carbon can inhibit combustion of the binder.
This container may affect the final firing temperature. You may need to lower the temperature because this container allows for a hotter firing due to the nature of the ceramic material. Fire test pieces. If the suggested firing temperature results in blisters or cracks, lower by 25F and retest.