Printing on polypropylene fails in the same way for everyone at first: the ink sits proud, looks acceptable, and comes off on the first thing that rubs it. The polymer has low surface energy and almost nothing wets it unaided, so every successful method either pre-treats the surface or uses an ink formulated to key into it.
Screen printing
Screen gives a thick, opaque deposit that covers well on coloured board and survives abrasion better than most alternatives. It suits simple artwork, spot colours and high contrast marks. Setup cost is real and each colour is a separate pass, so it favours longer runs and repeat orders rather than variable data.
Its weakness is exactly that thickness. A heavy deposit can crack along a fold line, which is whyscreen logos need to stay away from creases.
Inkjet and digital
UV-cured inkjet prints directly to the board and cures instantly, which makes variable data – serials, barcodes, batch codes – practical for the first time. No plates, no setup, so short runs and changeable artwork are economical.
Durability is respectable but below screen, particularly on anything that gets abraded. The typical answer is to place variable data where hands and product do not reach, and use screen for the permanent branding. The choices are laid out in more detail in our note on printing on PP sheet.
Hot stamping
A heated die presses pigment from a carrier foil into the surface. It gives a crisp, high-contrast mark with no drying time and very good chemical resistance. It does not like textured or corrugated surfaces, because contact must be complete – which is the reason it is rarely used on fluted board but works well on flat sheet and on moulded parts.
Surface treatment is the hidden variable
Corona or flame treatment raises surface energy so ink can wet and key. It works, and it decays – treated board loses its advantage over days to weeks, faster in warm storage. Printing onto treated board weeks after treatment produces exactly the adhesion failures people blame on the ink.
Ask when the board was treated. If nobody knows, that is usually the answer to why the print failed.
Test the failures that will actually happen
Three tests cover most real conditions: a solvent rub with whatever cleaning agent the pack meets, an abrasion rub with a cloth or thumb pressure, and a freeze-thaw cycle followed by the same rub. Tape tests are a reasonable proxy for adhesion but tell you nothing about abrasion life, which is the failure mode we wrote about in what print actually sticks to corrugated PP sheet.
Where to put the print
Print survives best away from contact points, fold lines, stacking interfaces and drainage paths. On a reusable box that tends to mean the upper face of a side wall rather than anywhere loads bear. Designing the artwork position around the pack’s wear points is more effective than specifying a better ink.
The honest cost picture
On a returnable pack the print will outlast its usefulness more often than not, because identification requirements change faster than the print wears off. Spending on the most durable method available is frequently wasted money; spending on the most legible placement rarely is.
What we can do
We print on corrugated PP sheet by screen and digital and advise on placement before we quote, because half of print durability is location. Send the artwork, the pack drawing and what the pack meets in service, and we will tell you which method lasts – or if the answer is a label instead.