All the fine silver dust, clippings and scraps removed after casting are then melted together and poured into a sand mold to create bullion bars. Because the silver used in these bars is paid for by the castings, these bars are additional profits that will be sold regardless of silver prices because these bars are 100% profit.
These bars are not used for casting jewelry because it has been used already and fresh sterling is best for finished product. These bars also contain traces of platinum, rhodium and gold. Many silver pieces contain rhodium and gold plating and cannot be mixed with sterling silver when casting so those other metals also end up in these bars.