Multilayer system: the addition of the plastic film was the first step to help make brick containers impermeable to liquids and heat-sealable. Inside the nineteen sixties, an aluminum foil started to be added for the cardboard container to guarantee greater security and lengthen the shelf life of the packaged item. https://gabletopmilkcarton.art.blog/2024/12/05/gable-top-cartons-the-future-of-sustainable-packaging/