Once conching is over; the chocolate has to be tempered in order to pass from a liquid to a solid state so it goes through a temperature cycle, very precisely calculated to encourage fine, stable crystallisation of the cocoa butter and its homogenous dispersal throughout the chocolate. Stored in tanks at 40°C, the chocolate enters a tempering machine, i.e. a cylinder with a dual casing, which cools it to 27°/28°c then reheats it to 29°/30°C for milk chocolate and to 31°/32°C for plain chocolate. This is known as the crystallisation curve.