Multilayer procedure: the addition of a plastic movie was the first step for making brick containers impermeable to liquids and warmth-sealable. From the 1960s, an aluminum foil began to be included into the cardboard container to be sure much better safety and lengthen the shelf life of the packaged solution. https://liquidsoappackage.blogspot.com/2025/04/the-rise-of-eco-friendly-packaging.html