How export chair cartons are specified — and why they fail
Packaging is the last thing a buyer specifies and the first thing they complain about. A carton that looks fine on the loading dock can arrive with crushed corners after 35 days at sea, and nobody agrees afterwards whose fault that was.
Published by JPChairs · Chair manufacturer in Foshan, China · 2026-10-13
What an export carton has to survive
Cartons leaving Foshan are handled far more roughly than anything in a domestic supply chain. Count the events: forklift onto the truck, manual stacking into a container, 30 to 40 days of vibration and humidity at sea, port handling, then a distribution centre and a last-mile van.
- Compression: cartons are stacked 8 to 12 high inside a container and bear the weight above them for weeks.
- Humidity: container interiors routinely sit at 85 to 95 per cent RH. Corrugated board loses roughly 30 to 40 per cent of its compression strength at that level.
- Point impact: a single drop on one corner damages the chair at the corner, not where the carton tore.
- Abrasion: cartons rub against each other for the whole voyage; printed surfaces scuff, and so does anything touching the board.
Board grade and flute: reading the carton spec
The two numbers that matter are the paper weight per ply and the bursting strength. A typical export chair carton in South China is written as 200/150/200 gsm five-ply K=K, meaning two outer liners of 200 gsm kraft, a 150 gsm middle liner and two fluting layers.
- Three-ply (single wall) at 175/150/175 is fine for light KD cartons under 12 kg and short voyages.
- Five-ply (double wall) is the default for assembled chairs and anything above 15 kg per carton.
- Bursting strength of 10 to 14 kgf/cm² is what we hold suppliers to; below 8 kgf/cm² the corners deform in stacking.
- Flute: B flute (about 3 mm) resists flat crush and prints well; C flute (about 4 mm) cushions better. Double wall usually combines them.
Ask for the mill certificate, not the quotation note. On bulk orders the board grade is the single cheapest thing to quietly downgrade.
Where chairs actually get damaged
Damage is predictable. In our claims data the same four points account for most of it:
- Leg tips — the leg end pushes through the board where the carton lands.
- Backrest top corners — the highest point inside the box, and the first to take a drop.
- Seat front edge — crushed when cartons are stacked with the seat facing the load path.
- Hardware — bolts and washers in a loose bag scuff upholstery and finishes.
The fix is not thicker board everywhere. It is 2 to 3 mm EPE sleeve on every chair, 5 mm EPE or moulded pulp on the four backrest corners, a divider sheet between stacked units, and hardware bagged and taped to the frame rather than dropped into the carton.
See how frames are built before they are packed on the factory frame assembly lines.
Stacking, pallets and drop tests
Two numbers settle whether a carton is adequate: required compression strength and drop height.
Compression: take the carton weight, multiply by the number of cartons stacked above it, then apply a safety factor of 3 to 5 for humidity and handling. A 16 kg carton with nine above it needs roughly 16 × 9 × 4, about 575 kg of board resistance.
Drop test: the common reference is ISTA 1A — ten drops covering one flat face, one corner, one edge and repeated cycles. Height follows weight: under 9 kg drops from 760 mm, 9 to 18 kg from 610 mm, 18 to 27 kg from 460 mm. Passing means the carton is intact and the chair inside is undamaged, not merely that the box looks acceptable.
Palletising changes the maths. On a pallet the bottom layer carries the load through the pallet deck and the board requirement drops, but you pay for the pallet volume — typically 8 to 12 per cent of a 40 ft container.
The packing spec to confirm before the first order
Put these six lines in writing before the deposit, not after the damage report:
- Board grade and ply with gsm per layer.
- Number of units per carton and carton gross weight.
- Protection list: EPE thickness, corner type, divider, hardware bag.
- Printing method and whether the carton is plain kraft or printed.
- Drop test standard and who pays if it fails.
- Whether chairs ship assembled, KD, or semi-KD.
Knock-down packing typically cuts shipped volume by 30 to 40 per cent against assembled chairs, which is why most container-quantity maths assumes KD. Browse the solid wood dining chairs and the export shipping FAQ for the volumes we quote against.
