fusion à fond de poche refroidi

OBS: skull. A layer of solidified metal or dross on the walls of a pouring vessel after the metal has been poured. The same term is used for the glass left in a ladle after most of the molten glass has been poured in glassmaking; in the glass industry the usual spelling is scull.
OBS: skull: the crust of solid material forming on the bottom of a ladle - fond de poche.