A nucleated casting apparatus including an atomizing nozzle configured to produce a droplet spray of a metallic material, a mold configured to receive the droplet spray and form a preform therein, and a gas injector which can limit, and possibly prevent, overspray from accumulating on the mold. The gas injector can be configured to produce a gas flow which can impinge on the droplet spray to redirect at least a portion of the droplet spray away from a side wall of the mold. In various embodiments, the droplet spray may be directed by the atomizing nozzle in a generally downward direction and the gas flow may be directed in a generally upward direction such that the gas flow circumscribes the perimeter of the mold.