délestage, or rack and return, is a cap management procedure which optimizes contact between must and solids during fermentation. When the cap has risen to the top of the tank, fermenting wine is taken from a bottom valve to a separate receiving vessel. The remaining pomace is allowed to free drain for two or more hours. The wine is then gently pumped back over the top of the cap, using a low pressure pump or sprinkler system. This procedure, usually conducted once or twice during fermentation, is designed to ensure optimum diffusion of tannins and pigments from the fruit into the wine. It may also used to remove a proportion of the seeds and can thus reduce the extraction of bitter tannins from unripe seeds. When the tank is wide rather than tall, maceration is more efficient so that délestage is not as useful. See also maceration.