Why Export Cartons Crush in Container Stacks

Quick answer

Export cartons crush in container stacks when real compression load, moisture exposure, pack geometry, and load distribution exceed the carton system’s usable strength. Raising ECT may help, but it will not fix an oversized carton, weak product support, or bad pallet pattern.

Calculate the real stack

Count cartons above the failed case, include pallet and handling loads, and distinguish warehouse stacking from floor-loaded container stacking. A carton tested at one stack height may see far more load during a long voyage.

Check humidity exposure

Corrugated strength declines as moisture rises. Look for container sweat, wet pallet decks, unprotected loading docks, and high-moisture product. Compare failed-carton moisture with retained dry samples.

Inspect board and conversion

Verify finished-board ECT, flute construction, glue bond, score quality, and box-joint integrity on the failed batch. Nominal paper weights or pre-production samples do not prove the delivered board met target.

Review carton geometry

Tall narrow cartons and large unsupported panels buckle more easily. Excess headspace lets the top panel deflect; poor fit between product and carton transfers the stack load to weak panels rather than contents.

Audit the load pattern

Overhang, uneven pallets, interlocked patterns that reduce vertical alignment, and voids in floor loads concentrate load. Photograph loading and measure the actual stack rather than judging from a warehouse plan.

Apply targeted corrections

Use tighter fit or inserts, improve pallet alignment, add moisture protection, revise board construction, or reduce stack height. Trial one change set at a time so the next shipment identifies the real improvement.

RFQ

Failed SKU; photos; measured stack and route conditions

Carton ID, packed weight, product support, and pallet pattern

Delivered ECT/moisture test request; sample retention

Proposed board/pack-out change and validation shipment

Related PackTrades Knowledge

How to Spec ECT and Board Grade for Export Cartons, Corrugated Board ECT and FCT Explained, Corrugated Sheet Spec Checklist for Carton Plants, Wood-Free Export Packaging Buying Guide.