Forging Technology of High-Tin Bronzes in Ancient Bengal

High-tin bronze or β -bronze, commonly known as bell metal came into existence as a cast metal since late second millennium BC. The general composition of 23 Sn–Cu holds good reputation as a castable alloy. But it offers enormous difficulty in forging due to its narrow forging range as well as its metastable thermodynamics of incomplete phases prevalent in the Cu–Sn system. Though widely used in castings for manufacturing gongs and bells throughout the world, only few people of the ancient world could achieve the mastery of forging this alloy into thin sheets. Ancient Bengal had been one of those few centres where circular bowls or tumblers or pots of very thin sections were manufactured. Some ethno-archaeological studies were also conducted on Bengal artisans presently engaged in this forging trade.