How corrugated board and boxes are made in India
A corrugator runs a fluting medium through hot, toothed rolls to form waves, glues it to a flat liner with starch, and adds more liners and flutes to build 3-, 5- or 7-ply board. Smaller Indian plants often run single-facer machines and paste the layers on a separate line; larger plants run full automatic corrugators. The sheets are then printed, usually by flexo, slotted and creased, and the box is closed at the manufacturer's joint by glue or stitching.
Most export cartons are regular slotted containers (FEFCO style 0201). Furniture, décor and lighting exporters also use die-cut trays, telescopic lids and inner partitions. Strength depends on three things: the grade of liner (virgin kraft is stronger than recycled test liner), the flute profile, and moisture. Indian liners are mostly made from recycled fibre, sometimes imported waste paper, so strength varies more between mills than buyers expect. Corrugated cartons (HS 481910) were US$61.4 million of exports in FY2025-26 (TradeStat, provisional), but far more Indian board leaves the country wrapped around other goods.
What we check on corrugated cartons
| Check | How it is checked | What fails |
|---|---|---|
| Construction | Cut edge examined for ply count and flute type; flute height measured | 3-ply where 5-ply was ordered; wrong flute |
| Liner and medium grammage | Board separated by soaking; layers weighed on a cut area | Lighter or recycled liner instead of the specified kraft |
| Moisture | Moisture meter on stacked boxes and inside the pile; oven-dry test where agreed | Board above the agreed moisture limit |
| Strength | Burst (ISO 2759), edge crush (ISO 3037) and box compression on the plant's tester, witnessed on samples from your lot, or by an accredited lab | Results below the specification |
| Dimensions | Internal length, width and depth measured; squareness when erected | Too tight for the product, or slack so the product moves |
| Manufacturer's joint | Glue line or stitches checked; flap opened by hand | Joint gaping, starved glue, missing stitches |
| Creasing and slotting | Box erected and folded; flaps closed | Cracked liners at the score, flaps not meeting or overlapping |
| Print and marks | Logos, handling symbols, shipping-mark panels and any box maker's certificate against the artwork | Smudged or missing marks; certificate values that do not match the board |
Board strength is not linear with ply count. Box compression strength depends mostly on the edge crush value of the board and the box perimeter, which is why two cartons of the same ply can perform very differently.
Common corrugated carton and box defects and how they are classed
| Defect | Typical cause | Class |
|---|---|---|
| Compression or burst below specification | Lighter or recycled liner, damp board | Major (critical where goods are heavy or fragile) |
| Wrong ply or flute | Substitution to save cost | Major |
| Delamination of liners from flutes | Starch not cured, low temperature | Major |
| Washboarding (flutes visible through the liner) | Thin liner, excess pressure | Minor, major if print is unreadable |
| Warped board | Uneven moisture between liners | Major if boxes will not erect on a packing line |
| Wrong internal size | Die or slotting set from external size | Major |
| Shipping marks blurred or misplaced | Flexo plate wear, wrong artwork | Major for barcodes, minor for logos |
Your defect list decides the final class.
Transit tests and market rules for cartons
- ISTA tests. Many retailers ask for an ISTA procedure: ISTA 1A as a basic integrity test, 2A as a partial simulation and 3A for packages sent through parcel networks. These need drop, vibration and compression equipment, so they are done in a lab on a packed product, not on empty boxes.
- US carrier rules. A box maker's certificate printed on the flap states the board's burst or edge crush rating and the weight and size limits under the US carrier classification rules (NMFC Item 222 and UFC Rule 41). The inspector checks the printed values against the board actually used.
- EU packaging regulation. Regulation (EU) 2025/40 applies from 12 August 2026: the sum of lead, cadmium, mercury and hexavalent chromium in packaging may not exceed 100 mg/kg, and manufacturers keep technical documentation and an EU declaration of conformity. From 1 January 2030 at the earliest, transport and e-commerce packaging must keep empty space to no more than 50%. Printing inks and recycled fibre are the usual sources of heavy metals, so ask the converter for test reports.
- EUDR. Paper and paperboard of chapter 48 are listed in the EU Deforestation Regulation. Empty cartons sold to an EU business as products are covered; packaging that only protects other goods is treated differently, so confirm your case with your EU adviser before 30 December 2026. See EUDR.
- FSC. An FSC mark on a carton needs the converter's chain-of-custody certificate. See FSC in India.
Wooden pallets under the cartons need ISPM 15 treatment and marking; paper and board do not. See ISPM 15.
Storage, loading and your carton specification
Empty board is often stored at the box plant or the exporter's packing area on bare floors in the monsoon, and it absorbs moisture fast. Before cartons are filled, the inspector checks the stock on pallets, away from walls and covered. In the container, the bottom tier carries the whole stack, so a carton that is fine on the factory floor may crush after weeks at sea. Corner posts, layer pads and correct stacking height do more for the bottom tier than an extra ply.
Put these in your carton specification:
- Box style (FEFCO code), internal dimensions and tolerance.
- Ply, flute and liner grade and grammage for each layer.
- Minimum burst, edge crush and box compression values, and the test method.
- Maximum moisture content at dispatch.
- Joint type (glued or stitched) and print artwork with shipping-mark panel.
- Gross weight per carton and maximum stacking height.
- Any ISTA procedure the packed product must pass.
We check cartons as part of every container loading supervision, and the furniture inspection guide shows how packing checks fit into a product inspection.