Bullas have been used from time immemorial for stamping documents, in order to keep

them from being opened by the wrong people. Ancient bullas were stamped while their

clay was soft and pliable. After which, it was necessary to wait a period of time to allow the

clay to harden before the document could be filed or delivered. This problem was solved

in the fourth century CE when sealing tongs (iron pincers) were invented (bullotarion in

Greek), which made possible the use of bullas produced from cold lead. The bullas were

manufactured in two steps. First, the blanks for the bullas were prepared in two sections

which were joined prior to casting; a cylindrical perforation having been made along their

length. Second, the ends of the string, with which the document or merchandise was

bound, were placed in the perforation of the blank bulla and the bulla was pressed

together with the bullotarion-pincers, the inner faces of which were engraved as minting

dies. This system was much quicker and more efficient than the previous ones and was

thus eagerly adopted in the Byzantine court, spreading slowly from there to the rest of the

empire. Up to the seventh century the use of lead bullas was limited, and only reached its

peak in the eleventh century. Subsequently, its popularity again declined because of the

high price of lead. Most of the bullas that have been found are decorated with Christian

motifs, such as scenes from the lives of the saints, Bible stories, monograms, and crosses,

and many are also engraved with personal names. The bullas exhibited here show the

menorah, probably indicating the Jewish identity of their owners.