are pushed outward and upward toward the rear of the container by thumb pressure, breaking the seal between the outside surfaces of the two lip panels, and breaking the seal in the rib panels surmounting the roof above the pouring spout. The gable edges are forced backward past the point at which the lip panels are joined, to nearly touch the roof panels.
Second, the gable edges are pushed forward and inward. The forces are communicated through spout panels to the tip of the pouring spout, breaking the seal between the lip panels and the underside of the roof panels and snapping the spout outward to a pouring position.
In early models of gable-top containers, the panels comprising the lips of the pouring spout were bonded to the underside ofthe roof panels. The resulting sealed spout was difficult to open, generally requiring insertion of a tool behind the lips to separate them from the roof underside. The cardstock panels often tore or delaminated, producing an unsightly and unsanitary container. In those cases where an adhesive was applied to only those panels which were to be joined, it was simple to eliminate adhesive from the spout panels to reduce the forces required to open the spout. The resulting container, of course, was not effectively sealed and was subject to leakage.
An improvement in gable-top containers to provide a hermetic seal for an extended shelf life package consisted of coating the inner surface of the container blank with a foil and an overcovering layer of thermoplastic such as polyethylene. The