Multilayer Process: the addition of a plastic film was the first step for making brick containers impermeable to liquids and warmth-sealable. Within the sixties, an aluminum foil started to be added on the cardboard container to be sure much better defense and extend the shelf life of the packaged item. https://sustainablemilkcartongabletop.blogspot.com/2025/01/gable-top-box-for-versatile-packaging.html