Packaging for food and beverage
Food packaging fails wet. Condensation in a chiller, grease from the product, humidity in a monsoon warehouse - each one attacks the same property, and the coating you choose to fight it decides whether the pack is still recyclable.
Moisture is the whole problem
Corrugated loses compression strength as it takes up moisture, and food lanes are wet in ways other lanes are not. A chilled or frozen product moving into ambient air condenses on its own surface; a produce pack sits in a humid cold store for days; a fried or fatty product wicks grease into the flute. In each case the board that was specified against a dry laboratory value is carrying its load with substantially less strength than the datasheet implies.
The engineering response is to specify against the real condition rather than the reference one. Strength values are quoted at the standard climate of 23 C and 50% relative humidity because that is the only way to compare boards to each other - it is not a claim about your cold store. Derate for the humidity, the dwell time and the creep the stack will actually experience.
Coatings decide your recyclability
This is the trade-off that defines the category:
- Wax - excellent moisture performance, and typically not repulpable. A wax-impregnated box is generally not recoverable in a standard mill stream.
- PE lamination - strong barrier, hard fiber recovery.
- Water-based dispersion coatings - can deliver real moisture resistance while remaining repulpable, but repulpability is a claim to be tested and accepted by the actual recovery stream, not assumed from a supplier datasheet.
The question worth asking is never "is this recyclable?" in the abstract. It is "is this recoverable in the stream this box will actually reach, in the market where it is opened?" Those answers differ across India, APAC and the US, and a pack that is repulpable in one market may simply not be collected in another.
Food contact is a compliance question, answered early
Where board contacts food directly, the materials, coatings and inks fall under food-contact regulation in the destination market, and recycled fiber content interacts with that. This is a constraint to establish before design, not a box to tick afterwards: it can rule out a furnish, a coating or an ink system entirely, and discovering that late means starting again.
Ventilation, stacking and produce
Produce packs need airflow, and every vent hole is a hole in a load path. Vent placement is therefore a structural decision as much as a cooling one - holes belong where the panel is not carrying, and the compression consequence has to be measured rather than estimated. The same logic applies to hand holes, which are convenient, popular with operators, and quietly expensive in stacking strength.
The test profile
ASTM D642 for compression, on samples conditioned to the standard climate, and an ASTM D4169 cycle or the relevant ISTA profile for the lane. Where the product is temperature-controlled, thermal performance needs its own validation rather than being inferred from a transit test. Incoming acceptance runs on ISO 2859 sampling with defect classes agreed in the specification.
What we need from you
- Whether the board contacts food directly, and the destination markets.
- The temperature and humidity profile: chilled, frozen, ambient, and the transitions.
- Grease or moisture exposure from the product itself.
- Stack height and dwell time in the coldest, wettest part of the chain.
- Any recyclability or recycled-content target you have committed to publicly.