Compression strength in a paper edge protector comes from three things: how much fibre is in the wall, how well the plies are bonded, and how dry the board is when it is loaded. A profile with a thicker wall but poor bonding is weaker than a thinner, well bonded one. That is why we quote compression by wall build and ply count rather than by a single thickness figure.
Compression grade data
| Failure mode | First lever | Second lever |
|---|
| Corner crush under stack | Wall thickness | Ply count |
| Band cutting the board | Wall thickness | Leg width |
| Surface mark | Leg width | Facing |
| Profile folds at the crease | Ply count | Fold radius |
| Softening in humid air | Coated face | Wall thickness |
Fibre, bonding and moisture
Thickness is a proxy for fibre content, but only a proxy. A 6 mm wall built from many thin plies bonds better than a 6 mm wall built from three thick plies, because each glue line adds stiffness and distributes the load between layers.
Moisture is the biggest single variable in service. Kraft loses a large part of its stiffness as moisture content rises, so a board that performs in a dry warehouse can fail in a humid container. This is why compression claims without a moisture condition are not meaningful.
How compression is actually tested
The honest position: an edge protector is not corrugated board, so an ECT figure from a corrugated test does not transfer. Compression is measured by loading the profile on edge between platens and recording the load at a set deflection, and the result depends on the profile geometry, the free length and the rate of loading.
We do not publish a single compression rating for that reason. What we do is quote a wall build against the application and supply samples so the buyer can run the profile on their own pack. Any supplier offering one universal number for every profile is simplifying past the point of usefulness.
When a heavier wall is the right answer, and when it is not
If the failure is a crushed corner under a stack, more wall helps. If the failure is a band cutting through, more wall helps less than a wider leg. If the failure is a surface mark, the answer is a wider leg or a different facing, not more fibre.
Above about 8 mm the profile becomes stiff and hard to fold tightly, and the fold radius starts to bridge the corner. At that point two thinner profiles back to back usually outperform one heavy profile.
Questions buyers ask before ordering
Do you provide a compression test figure?
We quote wall build and supply samples so you can test the profile on your own pack. A single figure across all profiles would be misleading.
Is a thicker board always stronger?
No. Bonding and moisture matter as much, and above 8 mm the fold becomes the weak point.
What wall for a stack of four pallets?
5-6 mm with 60-70 mm legs, and a doubled base where the load meets the pallet deck.
How does humidity affect it?
Kraft softens as moisture rises. Coated faces and keeping bundles wrapped until use are the practical controls.
Can you supply samples for a trial?
Yes, free on stock grades, in 3-5 working days.
Samples and prices are issued from mona@hengnicepacking.com once cut length, wall thickness and quantity are known.
