A strapping mark is permanent deformation under a band. It happens because the band applies a high force over a very narrow contact width, and paper, foam and soft timber all yield at that pressure. Preventing the mark is a matter of spreading the force over a wider strip, not of using a harder material, because a harder material that does not conform simply transfers the mark to the pack.
Anti-mark grade data
| Band | Leg width | Wall | Mark risk |
|---|
| 12 mm PP | 40-50 mm | 2.5-3 mm | Low |
| 19 mm PET | 50 mm | 3.5-4 mm | Medium |
| 32 mm steel | 60 mm | 4.5-5 mm | High at the seal |
| 50 mm steel | 70-80 mm | 5 mm doubled | High, double the board |
| Film only | 50 mm | 2.5-3 mm | Low |
Pressure, not force, is what marks the pack
The band tension is fixed by the tool and the load. What the protector controls is the area over which that tension is applied. A 12 mm band on a bare corner applies its load over roughly 12 mm; the same band over a 60 mm protector leg applies it over five times the width.
This is why a wide, relatively soft board usually outperforms a narrow, hard one. It is also why adding a second band without widening the protection can make marks worse: the total force goes up while the area stays the same.
Marks that are not really from the band
Some marks blamed on strapping come from the pallet deck, from a fork tine, or from two packs rubbing. Before specifying a heavier protector, look at the mark: a straight line parallel to the band is the band, a curved or irregular mark is handling.
On printed cartons, a mark can also be a print transfer from the board itself. White top board removes that risk on light print.
Where the protector goes, precisely
Under the band, centred, with at least 20-30 mm of board beyond the band on each side. A board that stops level with the band edge will tilt and concentrate load on one edge, which produces a mark worse than no board at all.
For film wrapped loads the same logic applies with lower force, so a 3 mm wall with a 50 mm leg is usually enough. For steel band the leg should be wider than the seal, because the seal is the hardest point in the system.
Questions buyers ask before ordering
Will a thicker board always stop the mark?
No. Width spreads the load; thickness resists cutting. Marks are usually a width problem.
What if the mark is already in the carton before strapping?
Then it is handling damage, not band damage, and a protector will not fix it.
Can I use foam instead?
Foam spreads load well but compresses out and holds moisture. Paper is the usual choice for export because it repulps.
Does the board need to be wider than the seal?
Yes. A seal narrower than the board still concentrates load, so allow 10 mm each side minimum.
Can you print the band position on the board?
Yes, which is a simple way to keep the band centred on a busy packing line.
For a specification sheet, post the load weight, pallet footprint and band type to mona@hengnicepacking.com; we reply with a drawing and price.
