Multilayer Method: the addition of a plastic film was the initial step for making brick containers impermeable to liquids and heat-sealable. While in the sixties, an aluminum foil began to be included into the cardboard container to make certain better safety and increase the shelf lifetime of the packaged item. https://www.tumblr.com/gabletoppak/763465487661285376/gabletop-pak-revolutionizing-packaging-with?source=share