Multilayer process: the addition of a plastic film was step one to create brick containers impermeable to liquids and heat-sealable. From the 1960s, an aluminum foil began to be included for the cardboard container to make sure better defense and prolong the shelf life of the packaged products. This method https://gabletopforsoappackaging.blogspot.com/2025/10/plastic-free-water-in-paper-pak.html