Polyethylene Coating: A skinny layer of polyethylene on each side delivers longevity. The outer layer protects the design and printing, although the internal layer functions like a sealant, generating the carton fully leakproof. The first patents for food stuff paperboard containers day back to the start of the last century. https://share.evernote.com/note/b0a0ca9c-9d1b-7129-6089-9b3a7535c26c