2,400. Pouring From Vessel to Vessel

Maachalos Assuros 12:12

If a person pours wine into a vessel that already contains non-Jewish wine, all of the wine in the upper vessel is prohibited because the stream of wine being poured connects the wine in the upper vessel with that in the lower vessel. Therefore, when one measures wine for a non-Jew into a vessel that he (i.e., the non-Jew) is holding, he should interrupt the flow to keep it from forming a connective and rendering the wine in the upper vessel prohibited.

Maachalos Assuros 12:13

If a funnel that was used to measure wine for a non-Jew is blocked so that the wine can’t flow, it may not be used to measure wine for a Jew until it has been scrubbed and dried. If it wasn’t scrubbed, the wine is prohibited.