Abstract: A disposable hot top board includes a compressible seal positioned along the outer surface of the board to form a seal between the bottom of the board and the mold wall. In a preferred form, the disposable hot top board comprises an insulating or exothermic material having a reticulated metal mesh embedded therein. A metal plate extends along at least a portion of the outer surface and a ceramic fiber strip extends along a bottom portion of the board. A perforated metal retention strip with a first end interwoven with the mesh and a second end extending outward from the board, is used with a big end up mold having a pair of slots. In addition to the standard internal wedge system, the board is forcibly retained against the ingot mold to compress the fiber strip into a seal by a rod which engages the metal retention strip in a wedging type relationship with the mold exterior.