Racking or clarifying wine is the step in the wine-making process in which the wine is siphoned out of one container and into another, leaving the sediment in the old container.
Clear wine must be removed from contact with the sediment after a minimum of three weeks and not more than three months. As the yeast that creates the alcohol dies and sinks to the bottom of the container, it begins to rot, and hydrogen-sulfide gas, which smells like rotten eggs, will accumulate in the wine. If the clear wine is not siphoned off, the sediment and gas will taint the flavor of the wine.
The wine container that needs to be racked is carefully placed on an elevated surface without disturbing the sediment. A sanitized hose is placed in the wine just above the sediment. The wine is siphoned into a lower, sanitized container. Siphoning ends just before the sediment layer is reached.
Wine is racked several times to ensure clarity and flavor. It is racked until little or no sediment appears in the container and at least one time after fermentation has ended.