Abstract: A method for controlling the foaming of slag in an electric arc furnace is disclosed. The furnace comprises at least one electrode column. Current is applied to the electrode column, causing an arc to form between the tip of the electrode column and the scrap, melting the scrap. Impurities in the molten scrap metal rise to the surface forming slag. A meter determines the total harmonic distortion associated with the system. If the total harmonic distortion is greater than a predetermined set point, and the scrap metal is sufficiently molten, then a foaming agent is added thereto.