Workers making sand molds to produce pig iron at a blast furnace in Pittsburgh, Pennsylvania. ca. 1905

ca. 1905

Workers making sand molds to produce pig iron at a blast furnace in Pittsburgh, Pennsylvania. ca. 1905

Workers making sand molds to produce pig iron at a blast furnace in Pittsburgh, Pennsylvania. ca. 1905. Copyright Keystone View Co. Molten iron would be poured into the molds and allowed to cool before the sand would be knocked off the pigs.