Each time a weld is made, a new disk is required. The disk sits on the bottom of the crucible. Its purpose is to hold the powdered weld metal until the reaction takes place. The slag produced by the reaction rises to the surface and the molten copper settles to the bottom of the crucible where it melts the disk and flows over the conductors to produce a permanent molecular bond.

Disks are available in three sizes:

B117A used in molds using #15 thru #32 weld metal (3/4" diameter).
Disks are included with the Weld Metal.