Labels for chilled and frozen food: face stock, adhesive and application temperature

1. The short version: it is a temperature problem, not an adhesive problem

The sentence we hear most is "your adhesive is no good". Almost always the same adhesive sticks perfectly on an ambient line and lifts on a winter line or in a chiller — and the difference is not the adhesive but the moment of application: the temperature of the label, of the substrate, and of the room. If any of the three is below the adhesive's activation temperature, the pressure-sensitive adhesive cannot flow or wet out. It feels stuck at the time and starts to lift a day later.

So this page runs in order: the three temperature definitions, face stock, adhesive families including low surface energy, and condensation and ocean containers — the last two are what Hong Kong, Macau and Southeast Asian orders most often miss.

2. Three temperatures, three different numbers

3. Face stock: rule paper out first

The rule of thumb: if it condenses, freezes or gets rubbed, paper is out. The classic frozen-food failure is "coated paper plus gloss lamination" — the film keeps the water out, but the paper has already swollen underneath it, so it looks like an adhesive failure when the face stock failed first.

4. Adhesive families (four families plus one grade)

5. Low surface energy: why PE and PP bottles keep failing

PE and PP are low surface energy materials. In the standard classification anything below 36 dynes/cm counts as low surface energy, and both polypropylene and polyethylene sit there: the adhesive cannot spread or wet out, so adhesion never develops (3M's surface energy classification). This is a different problem from "weak adhesive" — the same adhesive holds on glass and lifts on a PP bottle because the substrate, not the glue, is the variable.

Four fixes, cheapest first: ① specify a modified or LSE-specific adhesive (usually a modified acrylic); ② corona or flame treat the container (the blow moulder can do it, and the effect decays with time, so label sooner rather than later); ③ clean the surface — mould release agents, silicones, skin oils and dust all defeat the adhesive; ④ change to a mechanical route — a shrink sleeve, or print directly onto the container.

6. Condensation and containers: the section export orders skip

Labels that pass inspection at the factory and arrive looking second-hand almost always fail in transit. An ocean container sees diurnal swings of roughly 8–14°C, and internal relative humidity commonly cycles between 60% and 95%. When the steel skin drops below the dew point, water condenses on the ceiling and walls and drips onto the cargo — the industry calls it container rain. Paper face stocks absorb, dry and re-absorb in that cycle, changing dimension each time, so the adhesive line is repeatedly sheared: the edges lift first, then the whole label.

• Dry surface before labelling: a chilled product taken out of a cold store condenses immediately. Adhesive applied over a film of water is stuck to the water, not the container. Either label inside the cold store with a freezer grade, or bring the product up to temperature and let it dry.
• The first 24 hours matter most: do not go straight into a freezer or straight into a container. If the temperature swings before the adhesive has wet out, edge lift starts there.
• Bags and pre-chilled product: bring them up to the application temperature first; if you must apply onto frost, use a freezer grade and make sure the roller actually displaces the frost.
• Full containers: desiccant inside the cartons and cargo kept off the container walls substantially reduce direct container rain on the product.

7. Five things to get right on the line

1. Pressure and the applicator roller: an under-pressured roller shows no problem in summer and lifts the whole batch in winter. The roller must cover the full label width and be checked for uneven wear.
2. Edge margin: keep 3mm or more of face stock beyond the artwork so the adhesive has something to hold at the edge. Artwork to the trim line leaves no margin.
3. Curvature: below roughly 30mm radius, use a thin face stock with a soft adhesive and apply on the cylindrical section, away from a sharp shoulder.
4. Rolls and unwind direction: match the unwind direction, core diameter and gap to the applicator; excessive unwind tension leaves the label fighting the surface as it lands.
5. Coding: thermal transfer smears on cold, damp surfaces, and direct thermal fades with water and solvents. Pre-print batch and date codes, or use UV/laser coding; if you use thermal transfer, do it after labelling and before the cold store, and run an abrasion test.

8. Six checks before the shipment leaves

1. The minimum application temperature of the chosen face stock and adhesive is written on the specification and checked against the actual line temperature.
2. Room, substrate and label are all above that temperature — including for the 24 hours after application.
3. The surface is dry, oil-free and dust-free; PE and PP confirmed as LSE adhesive or surface treated.
4. A peel and edge check 24 hours after application, before anything enters a cold store.
5. Coding tested on a condensed or damp surface (ten rubs with a finger, no loss).
6. Export jobs: adhesive family confirmed for a hot, humid container (avoid hot melt) and desiccant packed inside the cartons.

9. Three questions buyers ask us

Can frozen food be labelled before freezing?

Yes, and it is the more reliable route: label while the surface is unfrozen and dry, allow the full 24 hours to set, then freeze or load. The reverse — freeze first, label afterwards — also works, but needs a freezer grade (application down to -20°C), firm pressure, and the frost layer physically displaced; frost is an insulator, so an adhesive applied onto frost is stuck to air. The cost difference between the two routes sits in the adhesive and line speed, not in the printing.

Can we use coated paper with gloss lamination in a chiller?

For a short cycle, in a dry cabinet with no condensation, yes. Anywhere it condenses — product coming out of a cold store, or a high-humidity container — no. The film keeps water out but cannot stop the paper swelling underneath it, and you get a label that blisters in the middle and cockles at the edges, which reads as a printing defect. For chilled and frozen, start from synthetic paper, PE or PET.

A label came off at the customer — how do we tell whose problem it is?

Look at which side kept the adhesive, then check three things: ① where the adhesive went (fully transferred means a surface problem; stayed on the label means it never wet out); ② where it lifted (corners mean pressure or curvature memory; the whole label means adhesive family or temperature); ③ when it failed (within 24 hours means application temperature; weeks later means weather or low-temperature resistance). Send us those three plus the line temperature, the substrate and the storage conditions, and it is usually settled in one round instead of a reprint.

10. Five things to send with an enquiry

1. What the label goes on (glass, PE, PP, PET, metal, paper) and whether the surface is smooth or curved;
2. Storage and shipping temperatures — chilled to what, frozen to what, and whether it travels by ocean container;
3. Label size, quantity, and whether it is roll-fed (with core diameter and unwind direction);
4. Whether you need batch, date or QR coding, and by which method (pre-print, thermal transfer, UV inkjet);
5. The destination market and the labelling requirements that apply — which fields, confirmed by you or your importer.

Related reading: Specifying a roll label, Food labelling for Singapore, Malaysia and Indonesia, Allergen labelling in four markets, Export carton marking, Ink safety for food-contact labels, Custom shapes, dies and die charges, Tamper-evident seals and security labels, GS1 logistics labels and SSCC-18, Roll label storage and shelf life.