Four metallurgy kilns and a considerable number of parts from disposable clay moulds used for producing bronze flans were discovered at the northern part of the east wing of the Roman Forum in Thessaloniki. This find identifies the area as the mint of the city during the third and the fourth century AD.
The use of moulds of this type insured the massive production of a large number of bronze flans, up to 192 of each clay mould. Two rows of 8 wax flan figurines were pressed on each side of a long, raw, clay sheet, in a way that the two columns were separated, thought the wax flans of each raw were successively in touch. Only the two last flans of each column were in touch, while the two first flans communicated through a narrow casting channel. Each sheet was then wrapped within a larger sheet of raw clay, except for the surface with the casting channel. Six of these panels were joint together to create a clay mould.
The moulds were then fired in the kiln while rejecting the wax and thus creating the space that the molten metal would occupy to form the flans. When the metal became solid the craftsman carefully broke the clay moulds, trying not to injure the flans and to retain the connection of the rows. This would save him valuable time while stamping the flans. One of the sherds had four corroded bronze flans in its circular sockets, providing a good example of an abortive attempt to detach the flans from the mould. The examination of the sherds shows that the mint produced flans in five different sizes.
In the photo, a modern representation of the ancient clay moud is depicted on the right.
The exhibit is located at the temporary exhibition "Copying (in) the past: imitation and inspiration stories". From December 2019 onwards, it will be returned to the permanent exhibition "Thessaloniki, Metropolis of Macedonia".