Multilayer method: the addition of a plastic film was the first step to create brick containers impermeable to liquids and heat-sealable. Inside the 1960s, an aluminum foil started to be added into the cardboard container to make sure far better protection and lengthen the shelf lifetime of the packaged solution. https://gabletoppackaging.blogspot.com/2025/08/water-in-paper-pak-smart-sustainable.html