Multilayer process: the addition of a plastic movie was the first step to make brick containers impermeable to liquids and warmth-sealable. Inside the 1960s, an aluminum foil started to be added on the cardboard container to be sure much better defense and prolong the shelf lifetime of the packaged item. http://cartongabletop.car.blog/2024/10/05/revolutionizing-packaging-the-role-of-water-in-gable-top-cartons/