Stainless steel knives are used to uniformly cut the curds at various points during the process. The device is a stainless steel frame with stainless steel wires, which cuts the curd cleanly. Vats will vary depending on a variety of factors, but in general are in the shape of an oval or rectangle with hollow walls that are used for holding warm water to keep the curds at desired temperatures. This part of the vat is referred to as the jacket. A milling machine is used to cut the matted curds that are formed during the cheddaring process. This allows the curds to be easily salted.