Continuous casting (con-casting) is the process whereby molten steel is solidified into a "semifinished" billet, bloom, or slab for subsequent rolling. In older methods, steel was poured into individual molds to create ingots, which resulted in significant waste and chemical inconsistencies. In a modern tube mill supply chain, the continuous caster allows molten metal to flow from a ladle into a tundish and then through a water-cooled copper mold. As the steel moves downward, it solidifies into a continuous strand. For the tube industry, this is vital because it ensures the chemical composition—the levels of carbon, manganese, and silicon—is uniform throughout the entire coil. Without this uniformity, the high-frequency induction welding used to close a tube seam would produce "cold welds" or weak spots.