When a barcode stops scanning on a returnable box, the instinct is to buy a stronger adhesive. That is sometimes right and usually not. Most label failures are geometric: the label is sitting on a curved face, inside a rub path, or across a handle where it gets gripped. Move the label before upgrading the adhesive and the problem often disappears.
Choose a flat panel and keep it flat
A barcode needs a flat, uninterrupted area larger than the label with a quiet zone around it. On a corrugated PP box that means a flat face, not a fold, not a corner radius and not a ribbed area. If the box has a recessed label panel, use it – recessed panels keep the label below the rub surface of the walls around it, which is the single biggest contributor to label life.
Stay out of the three rub paths
Three places destroy labels on a box in service. The base edge, which is dragged every time the box is slid. The handle area, which is gripped and flexed. And the outer face at stack height, where the box above bears and slides during transit. Put the label on the end panel, above the base edge and away from the handle, and it will outlast the same label on the side by a wide margin.
Surface preparation is cheap
PP is a low-surface-energy material and labels do not naturally bond to it well. Two cheap mitigations: wipe the panel with an alcohol-based cleaner before application and let it dry, and apply with firm pressure at a temperature above about fifteen degrees. A label applied cold, on a dusty panel, with light pressure will lift at a corner within a week, and it will lift regardless of what the adhesive cost.
When to stop using labels
If the identification is permanent – a box serial number, an owner, a date of manufacture – do not label it. Print or emboss it into the box during manufacture, or fit a riveted or welded ID plate. Permanent identification survives washing, solvents, abrasion and the label gun being empty. Labels are for variable data; permanent marks are for everything else. The fifty-wash test is described in getting barcodes to survive fifty washes.
Size the label for the scanner, not for the eye
A barcode that a human can read comfortably is not necessarily one a scanner reads reliably at the working distance. Scanning reliability depends on the quiet zone around the symbol, on the contrast between bars and background, and on the surface being flat across the whole symbol. A label that fits the panel with a millimetre to spare on each side will scan badly from the first day, because the quiet zone has been squeezed out.
Specify the panel around the label rather than the label around the panel: the panel should be at least the label size plus six millimetres on every side, and it should be flat across that whole area. Where boxes are scanned in a stack rather than individually, the panel has to be visible in the stacked state, which usually means the end of the box and a position above the rim of the box below. Getting this right at specification stage costs nothing; retrofitting a fleet with a relocated panel is not worth doing, so it is worth getting right the first time.
Two labels beat one
A single label on a box has to serve transport, storage and picking, and those want it in three different places. Two labels cost almost nothing more and remove the compromise: one on the end panel for transport and stack identification, one on the front for picking and for reading at the face. Where a box has a recessed panel on each, both are protected.
Keep the data on the two labels different where it helps – the transport label carrying destination and contents, the pick label carrying part number and a large readable description – because the person reading each one wants different information. Where both labels carry a barcode, they should carry the same identifier so a scan at either position returns the same record, and the scan should work in the stacked state for the end label and in the shelf state for the front one.
What we can do
We build PP corrugated turnover boxes with recessed label panels positioned out of the rub path, and we can add printed or embossed permanent identification. Tell us what has to be scanned and how often the box is washed, and we will place the panel for that – not wherever the drawing happens to have space.