The time it takes for a variety of silicon inoculants to be melted in grey iron has been theoretically and experimentally evaluated. Heat mass-exchange involved in the movement mechanism for lumps of an inoculant in molten grey iron is the process which determine the intensity of the inoculant pick-up. The melting time and its temperature, lump size and preheating dependencies can be used to make the best choice of the inoculant composition.