Once coffee cherries have been delivered into the mill (see Part 1 above), the process of separation begins. After the truck dumps the lot into the receiving tank, there's an exit chute at the bottom of the those tanks that cherry tumbles into and down into a flume where water and gravity transport everything that was in the truck delivery--ripe cherry, unripe, leaves, small stones, twigs...everything--into a large hopper filled with water, with a pipe chute out the side that feeds into a slightly lower, smaller holding bin. The water in the large hopper plays a critical role in the separation process. Since the mass of water is heavier than all the foreign material as well as the unripe coffee cherry, it causes most of those to float. Ripe cherry, however, is heavier than water, which causes it to sink and be separated into the next holding bin below and to the right. Hence, the pipe chute feeding the smaller bin is toward the bottom of the large bin. The gratings at the entry of the smaller bin allow most of the water to escape below, where it will be recycled into pulper(s) on the next level down. It is often difficult to distinguish which cherry is fully ripe and which isn't when it's on the tree. Both may be bright red. More or less sugars inside the cherry means more or less density vis-a-vis the water, and that's the brilliance of this simple separation technique. The thing to notice here is that while there may be upwards of 15+% unripe cherry and foreign materials feeding into the big hopper, that number has been reduced to around 5% by the time it reaches the lower hopper. From here, the unripes will be processed and prepared for the local commodity market, while the ripe cherry continues its journey to the depulping