Multilayer technique: the addition of a plastic film was the first step to make brick containers impermeable to liquids and warmth-sealable. During the sixties, an aluminum foil began to be additional towards the cardboard container to make certain far better safety and extend the shelf lifetime of the packaged merchandise. https://sustainablemilkcarton.blogspot.com/2025/04/the-sustainable-revolution-with-gable.html