Multilayer method: the addition of the plastic movie was the first step to make brick containers impermeable to liquids and heat-sealable. In the nineteen sixties, an aluminum foil began to be extra for the cardboard container to make sure greater defense and lengthen the shelf life of the packaged item. https://sustainablemilkcartons.blogspot.com/2025/02/gable-cartons-future-of-packaging.html