Ancient bronze helmets tended to be simple in construction, without a system of suspension to distribute the weight. The armor of the Greek infantry, or “hoplites,” was typical of the time, according to study materials provided by Vincent J. Rosivach, classics professor at Fairfield University. Although the helmets’ design was basic, their manufacture required sophisticated metalworking.
An alloy of copper and tin, bronze improves upon plain copper, which is much too soft for armor and weapons; if the alloy contains more than 10 percent tin, however, the material becomes brittle, a disadvantage in a helmet. David K. Jordan, professor emeritus of anthropology at the University of California San Diego, explains that additional material, such as arsenic, antimony and lead, could change the softness and color of the final material; arsenical bronze is the hardest.
While casting, or using molds, is the preferred way to make statues and ornaments, it is time-consuming and impractical for items made from sheets of bronze, such as helmets, shields and armor. A helmet is cold-hammered over a rounded post, in stages, so that the sheet of bronze gradually forms a shape that will fit over the head. Hammering weakens the metal’s structure, however, so it must be annealed. Annealing, Jordan explains, means that the hammered bronze is heated red-hot, then allowed to slowly cool back to room temperature. Ancient armorers painstakingly pounded, then annealed, the helmets in a series of gradual stages.
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