Curious Facts / Everyday Life
Why is there wavy paper inside corrugated board?
Look beyond a parcel box’s smooth surface to the layers at its edge.
It is more than one thick sheet
At the edge of corrugated board, small waves run between flat surfaces. The flat sheets are liners; the wavy inner paper is the fluting, or corrugating medium.
Single-wall board has one fluted layer glued between two liners. What looks like one thick sheet from outside is a structure of joined layers with different roles.
How the paper is joined matters
The joined liner-and-fluting structure is designed to be stronger than its separate paper layers. The wavy medium, bonded to the flat layers, contributes to the stiffness of the whole board.
Look at the layers and flute shape as well as the paper thickness. Not all corrugated board has only these three layers: other types use additional fluting and liners. The single-wall example does not describe every box.
What did you discover?
2 questions · Read the explanation and evidence, then continue to the next question.
Sources and scope
- FEFCO — Corrugated board production
Opening construction paragraphs: liners, fluting, single-wall and other board types
- FEFCO — More: What is corrugated?
Basic raw materials: joined layers, rigidity and resistance; Construction Types
Scope of this fact
- The diagram shows single-wall board. Other boards have different layer counts and flute sizes.
- This explains structure, not a box’s rated load or packaging performance.
Original writing and English translation by Rantap