The pressing process is recommended to separate fat in beef, pork, and poultry. The separation between liquid and solid is done using a helical shaft that presses the product against a pressure box. In most cases, the material to be pressed must be cooked and pre-conditioned at a given temperature, so that the particles have a maximum size so as to obtain maximum mechanical extraction efficiency. The process can also be used to separate water during feather transport. Special presses are used to separate stickwater from hydrolyzed feathers and fish, as well as to extract vegetable oil from seeds.