What must be packed after completing the bottom of the base in the Boutet packing routine?

The correct process in the Boutet packing routine involves ensuring that the heel of the molds is properly packed after completing the bottom of the base. The heel refers to a specific part of the mold that plays a critical role in providing support and stability to the weld and preventing any excess material or slag from interfering with the thermite reaction. Proper packing in this area is essential to ensure that the thermite weld is completed effectively and that the structures being joined receive the necessary strength and integrity throughout the weld zone.

While packing the top, side, or base of the molds is important in their respective contexts, focusing on the heel after the bottom of the base ensures that the weld quality is uncompromised and solidifies the overall process completion. This sequence in the routine is crucial for achieving optimal results in thermite welding.