You often see this traditional method of clarifying wine performed during winery tours. After the fermentation process is completed, wine needs to be clarified because it's usually loaded with sediment. Less expensive wines are simply filtered through paper or synthetic mesh, or run through a centrifuge—quick and easy, yes, but it also reduces some of their more desirable qualities. During the wine's maturation period the sediment (or lees) naturally gravitates to the bottom of the tank or barrel. The sediment-free portion of the wine is then pumped into another tank or barrel (which explains all those big fire hoses attached to the tanks). The racking process is repeated up to half a dozen times in the first year, and is very labor intensive. It's also somewhat risky because, although aeration of wine helps to eliminate off odors and mercaptans, if the wine has too much contact with air, the winemaker could be left with some very expensive barrels of vinegar. See also centrifugation, cold stabilization, filtering, and fining.