For production, milk from the evening milking is used, which is left to rest in steel tanks overnight. After being partially skimmed, the evening milk is decanted together with the morning milk into the characteristic inverted bell-shaped copper cauldron, without the addition of any additives. The natural whey starter is then added and heated to 33 °C. Once the temperature is reached, calf rennet obtained from the stomachs of suckling calves is added until coagulation, which takes 10-15 minutes. The curd is broken into small granules and the cooking phase then begins at 55 °C. The mass obtained after cooking and falling granules is lifted and cut in two; each mass is wrapped in a linen cloth and placed in a wooden or Teflon mould. Here it takes on its characteristic shape and receives a casein plaque, embedded in the surface of the rind, which, thanks to an alphanumeric code, uniquely identifies each cheese wheel. This is followed by branding with the branding band, which impresses the following on the rind: the dotted inscription 'PARMIGIANO REGGIANO', the registration number of the dairy, the month and year of production. This is followed by salting, which takes place by immersing the cheese wheel for 16-20 days in a saturated solution of natural salt, and finally by maturing on wooden boards in suitable premises with controlled temperature and humidity, which lasts from a minimum of 12 months to over two years. Only those cheeses that pass a very strict selection process are branded with the oval firebrand mark at the age of 12 months.