Cast iron
Cast iron is made from pig iron, which is the product of smelting iron ore in a blast furnace. Cast iron can be made directly from the molten pig iron or by re-melting pig iron, often along with substantial quantities of iron, steel, limestone, carbon (coke) and taking various steps to remove undesirable contaminants. Phosphorus and sulfur may be burnt out of the molten iron, but this also burns out the carbon, which must be replaced. Depending on the application, carbon and silicon content are adjusted to the desired levels, which may be anywhere from 2–3.5% and 1–3%, respectively. If desired, other elements are then added to the melt before the final form is produced by casting.
Wok
Woks can also be made from aluminium. Although an excellent conductor of heat, it has somewhat inferior thermal capacity as cast iron or carbon steel, it loses heat to convection much faster than carbon steel, and it may be constructed much thinner than cast iron. Although anodized aluminium alloys can stand up to constant use, plain aluminium woks are too soft and damage easily. Aluminium is mostly used for wok lids.