Abstract: An edge sealing apparatus for composite boards comprises a heatable iron body having a bottom, presser surface formed with a shape or profile which conforms to that of the edge of the composite board to be sealed. In the method of edge sealing, the iron body mounts a slot nozzle formed with a discharge outlet having the same profile as the iron body and the edge of the board. The slot nozzle receives a sealing material such as hot melt thermoplastic adhesive from a dispensing device, and is effective to apply a coating of the hot melt adhesive along the entire surface area of the profile of the board edge. Immediately after the hot melt adhesive is applied to the edge of the board, the presser surface of the heated iron body presses or fuses such material therein to provide good penetration into the board edge and thus obtain a substantially complete seal.