The base core of the bell mould is made of refractory bricks coated with a mixture – made of clay, horse dung, and goat hair – that has been well kneaded in a baker's mixer. This very reliable recipe was invented in ancient times by the Egyptians to melt their jewellery, statues, or weapons. This allows the mould to withstand temperatures of over 2,012°F (1,100°C). The clay from the region is still used today and the horse dung is supplied by a nearby farm.