Multilayer technique: the addition of a plastic film was the first step for making brick containers impermeable to liquids and heat-sealable. In the sixties, an aluminum foil started to be included for the cardboard container to make sure much better defense and lengthen the shelf lifetime of the packaged product. https://sustainablesoappackagings.blogspot.com/2025/03/gable-top-carton-revolution-in.html