Although related, the processes of iron smelting and forging are distinct. Smelting must occur first, as it removes unwanted materials from iron ore in a furnace and produces bloomery iron ready to be molded in a forge by a blacksmith. In order to remove the unwanted materials from iron ore, smelters developed a range of efficient techniques to reach and sustain the staggeringly high temperatures necessary to produce high-quality iron blooms. This process is known as “birthing,” as the iron is produced in the furnace’s belly and delivered through a series of laborious steps.
One type of furnace is an earthen furnace. Constructed to feed the fire by natural draft, earthen furnaces functioned like a chimney so that the rush of air from bottom to top intensified interior temperatures. Other types of furnaces required bellows made from leather, clay, or wood.
Blacksmiths use a variety of tools while forging iron, including stone tools such as basalt hammers. Basalt hammers are very efficient tools because the stone does not absorb heat as quickly as steel, allowing the blacksmith to continue working without reheating the iron as frequently.
Environmental Impacts of Iron Smelting
In order to create iron objects, blacksmiths must have access to iron blooms whose unwanted materials were removed during the smelting process. Iron smelting requires a furnace supplied with a steady input of long-burning charcoal to create consistently high temperatures. The production of charcoal necessitated slow-growing tree species, which provided dense wood ideal for long-burning charcoal. Unfortunately, this practice resulted in gradual deforestation, altering the African landscape. With fewer trees as natural defenses, many early African communities were conquered by invading armies who took control over iron and other valuable resources.
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