Multilayer method: the addition of a plastic movie was the first step to generate brick containers impermeable to liquids and heat-sealable. During the nineteen sixties, an aluminum foil started to be included to the cardboard container to be certain greater security and extend the shelf life of the packaged product. https://durablegabletop.blogspot.com/2025/08/water-in-paper-pak-smart-sustainable.html