Abstract: The invention concerns a method of producing a packing blank consisting of a rigid plate material, e.g. cardboard, and a cover of foil material enclosing the plate material, said cover consisting of two pieces of foil, each being glued to its respective large surface of the plate material and subsequently welded together along the edge areas protruding beyond the plate material, according to the invention, an adhesive is applied to a first foil material by being pressed out over an area corresponding to the large surface of the plate material, the plate material is placed with one of its large outer surfaces on said area, an adhesive is applied by expression to the other large, free outer surface of the plate material, and a second foil material is placed on said surface, whereupon the foil materials are welded together along the said edge areas.