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Lead seals
Lead seals
Lead seals appeared in various parts of the globe and were used by some famous chanceries. The use of lead was borrowed from the Eastern Roman Empire and was typical of the papal chancery and territories under Byzantine rule, such as the Exarchate, Sardinia and all South Italy. Thus, the use of lead seals that originated in the East spread over a very large area, whereas wax seals were prevalent in the West.
Some authors believe these two trends were a result of the difficulty in procuring lead in Western Europe, whereas the rich mines in the Balkans and Sardinia supplied the East. Other theories that are not always supported by historical or scientific evidence have been put forward and suggest that wax seals may have deteriorated rapidly in hotter southern latitudes, thus prompting chanceries in these geographical areas to use the more resistant lead seals. The addition of antimony to improve its mechanical properties, and of arsenic to enhance smelting, endowed lead with a plastic property enabling it to receive the impression of the seal matrix made in harder metal. Furthermore, adding tin to lead lowered the melting point and made the final product much more resistant.
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