Gouging, also known as Air carbon arc cutting, is an arc cutting process where metal is cut and melted by the heat of a carbon arc. Molten metal is then removed by a blast of air. It employs a consumable carbon or graphite electrode to melt the material, which is then blown away by an air jet. This process is useful for cutting a variety of materials, but it is most often used for cutting, and gouging aluminum, copper, iron, magnesium, and carbon and stainless steels. Air pressures for the jet usually vary from 60 to 100 psi. The carbon electrode can be worn away by oxidation from heat buildup. This can be reduced by coating the carbon electrodes in copper.