Surface or reverse? Choose the ink by the failure you cannot afford

Most ink problems we are asked to solve start with the wrong question. The question is rarely “which ink is better” — it is “which side of the film is the print on, and what happens to it after printing”.

Surface printing: the print is the product surface

A surface ink is printed on the outside of the film. Everything the package meets — a pallet, a wet shelf, a scuffing carton — meets the ink first. So the ink has to deliver:

• adhesion to treated BOPP or PE at production speed;
• rub and scuff resistance after conversion;
• colour that does not shift under light or handling.

Because nothing is laminated over it, there is no second chance. A surface print that fails adhesion fails visibly, in the market.

Reverse printing: the print is protected, the interface is not

A reverse ink is printed on the inside of the film and then laminated — to a second film, or to a cast-film extrudate in the case of woven bags and non-woven fabric. The print is now sealed between layers, so scuff resistance matters less. What matters is the interface:

• bond strength between ink and substrate, and between ink and adhesive;
• solvent residue, because trapped solvent destroys the bond from inside;
• heat resistance, if the pack is going to a retort.

The practical test

If the job fails, ask where it fails. A surface print that rubs off points at resin and treatment level. A reverse print that delaminates points at solvent retention, adhesive mismatch or priming — usually in that order.

We keep both platforms in-house for exactly this reason: the same technical team tests the same substrate under both systems, and can tell you which variable moved. Send us the substrate, the press and the failure mode, and we will tell you which of our grades to try first.

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