Multilayer process: the addition of the plastic film was step one to help make brick containers impermeable to liquids and warmth-sealable. From the nineteen sixties, an aluminum foil started to be included to the cardboard container to be sure greater protection and extend the shelf life of the packaged products. https://www.tumblr.com/waterincarton/785845527264854016/redefining-responsibility-gable-top-containers?source=share