Typically the games of clean barley are dropped of the silo to a tank of partially full water soaking, to about 15 ºC. Many tanks of soaking are simple vertical cylinders with conical base. The content of the tank airs intensely insufflating air through water of soaking by means of the use of perforated pipes or by suction. Most of the soaking tank is vertical tanks of little height and flat bottom. They allow aeróbicas conditions in the soaking water. The water content of grains increases quickly from the immersion, but the speed of the increase of the content of the water descends after a progressive way. The speed of the rehumidificación is function of the conditions in which the barley has grown, of the variety of this one, as large as the grains and of the temperature of the water. Also it is considerably influenced by the mechanical damage that has been able to undergo grains during the soaking. The soaking is interrupted by drainage to the 12 - 24 hours. Each grain of barley remains covered of a water film through which the oxygen of the air of the surroundings can dissolve. This condition it is known him as air rest. When the barley has been soaked the water penetrates through the husk and the cover of the fruit and enters the grain through micrópilo. The embryo takes water quickly, however endospermo is hydrated more slowly, any fracture undergone by the husk or the covers of the fruit and the seed facilitate the humidification of endospermo or the embryo and, of course the flight of soluble substances of endospermo. This it constitutes one of the sumandos that give account of the losses suffered during the malteado one; another one is the represented one by the breathing of the embryo, that consumes reserves of nutrients, releasing carbon energy, dioxide and water. The breathing significantly increases when the embryo activates, which creates a demand of oxygen in the soaking water. In oxygen absence the embryo can metabolizar the reserves anaeróbicamente, but of a power little effective way, turning them dioxide of carbon and alcohol. As the alcohol concentration increases its toxicity is growing.