Iron can be obtained in two forms through the smelting process. Wrought iron is more pure, having less than 0.3% carbon and 1% or 2% slag. Cast iron contains 2% to 4% carbon, plus a mixture of other impurities. Wrought iron is considered superior in strength over cast iron; it never does reach a truly molten state and must be hammered into the desired shape. Cast iron can be poured into casting molds and so is easier and cheaper to use.

Wrought iron was first used in Asia Minor before 1000 B.C. and was used in making tools and weapons. Both cast and wrought iron were in use at about the same time in China, about 300 and 600 B.C. respectively. During the Middle Ages, wrought iron was used in Europe for detailed grille work, balconies, and other appointments. Cast iron was produced but not widely used until...