In the case of apples, artisanal producers then put the juice, or must, into tanks where a prefermentation clarification, known by the off-putting term defecation, occurs. In defecation, the fruit pectins coagulate and a gel-like substance, which traps impurities, rises to the top and forms a cap called the chapeau brun, or brown hat. Solid matter falls to the bottom of the tank, constituting the lees. The clear juice is racked into wood casks or tanks, where the alcoholic fermentation takes place, lasting anywhere from two to six months. When the cider reaches the sugar-to-alcohol balance desired by each producer, it is racked, then bottled for the prise de mousse—the process by which the bubbles are formed.