Every ten minutes when the loaves must be turned over, they are stacked. This step uses the weight of the loaves upon each other to help expel additional moisture. The first time this occurs, two loaves are stacked together. The next time, the loaves are turned, and two stacks of two are put together. When the stacks get large enough (in general, 4 high), stacking stops but the loaves are still turned every ten minutes. This process is complete when the acidity of the whey is between 5.1 and 5.3, so it is checked constantly.