Pecorino sardo is an uncooked hard cheese made from fresh whole sheep's milk curdled using lamb or kid rennet. The mixture is poured into moulds that will give the cheese its characteristic shape. After a brief period in brine, the moulds are lightly smoked and left to ripen in cool cellars in central Sardinia. The average weight of the finished product is 3.5 kg (7.7 lb): sometimes a bit more, sometimes a bit less depending on the conditions of manufacture. The rind varies from deep yellow to dark brown in colour and encases a paste that varies from white to straw-yellow. The sharpness of the flavour depends on the length of maturation. The young pecorino sardo is about a couple of months old; the mature type is more than six months old and needs strictly controlled temperature and humidity.