Manufacturing
Producing lead shot from a shot tower was pioneered by William Watts of Bristol who adapted his house on Redcliffe Way by adding a three-storey tower and digging a shaft under the house through the caves underneath to achieve the required drop. The process was patented in 1782. The process was later brought above ground through the building of shot towers.
Molten lead would be dropped from the top of the tower. Like most liquids, molten lead becomes spherical as it falls. When the tower is high enough, the lead droplets will solidify while still dropping and thus will retain their spherical form. Water is usually placed at the bottom of the tower, causing the lead to be cooled immediately after dropping.
Roundness of manufactured shot produced from the shot tower process is graded by forcing the newly produced shot to roll accurately down inclined planes. Unround shot will naturally roll to the side, for collection. The unround shot was either re-processed in another attempt to make round shot using the shot tower again, or used for applications which did not require round shot (e.g., split shot).
Hardness of lead shot is controlled through adding variable amounts of tin, antimony and arsenic, forming alloys. This also affects its melting point.
The Bliemeister method, named for inventor Louis Bliemeister, is a process for making lead shot in small sizes. In this process, metered molten lead is dropped approximately 1 in (2.5 cm) into hot water, rolled along an incline and then dropped another 3 ft (91 cm). The water temperature controls the cooling rate of the lead, while the surface tension brings the ball into a spherical form.
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