A metal stream is protected from atmospheric contamination during casting by shrouding it with an inert gas from a gas source at the pour nozzle. The gas is supplied to a low turbulence zone at the nozzle which has a width at least one third of the length of the poured metal stream. The gas source may be an annulas surrounding the nozzle and having its inwardly and downwardly facing surfaces of perforated metal sheet and the outermost surfaces may be disposable in order to tolerate metal splashing. The need for a tube to enclose the protective gas is avoided.
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