Abstract: A sealing structure is disposed between a metal-casting ingot mold bottom portion and a bottom plate to prevent the leakage of molten steel between the mold and plate. A clay rope disposed in a closed configuration corresponding to the bottom of the ingot mold is affixed to the cardboard sheet with an adhesive system. Overlapping portions of the cardboard sheet are grasped to position the clay rope directly under the ingot mold, and the mold is lowered onto the bottom plate. Hot glue (or pressure sensitive adhesive tape and/or white glue) holds the clay rope on the cardboard sheet. The clay rope is offset at a central portion of the sheet to allow folding of the sheet for transport.