This invention relates to a method for reinforcing and repairing cast iron molds by surrounding the mold with a closely fitted steel plate or plates, connecting the ends of the steel plate or plates to form a continuous band, attaching the continuous band to the cast iron mold and locating spacers between the cast iron mold and the continuous band to elevate the band from the cast iron mold wall surface. This invention further relates to a method for reducing shear stress on the means by which the continuous band is attached to the mold by locating the means of attachment around a corner from the source of stress at an obtuse angle to the mold wall being reinforced.