Polyethylene Coating: A thin layer of polyethylene on both sides provides toughness. The outer layer safeguards the look and printing, though the internal layer acts as being a sealant, making the carton totally leakproof. The 1st patents for meals paperboard containers day again to the start of the last century. https://ecofriendlypackagingforwater.blogspot.com/2025/05/driving-sustainability-through.html