What is Corrugated Cardboard?

            Corrugated cardboard, sometimes called corrugated, is a sturdy packaging material made of three layers of kraft paper. It’s named for the interior layer of wavy paper, also called the corrugated medium, which strengthens the cardboard. During manufacturing, the inner sheet is put through the corrugation process to create flutes or stiff folds in the paper. The corrugated medium is then glued in between two sheets of kraft paper, which form the exterior liners. Thanks to the three-layer structure, corrugated cardboard is much stronger than regular cardboard.