How to Read Corrugated Board Spec Sheets from China

Quick answer

Read a corrugated-board spec sheet as a construction plus test conditions, not a strength label. Confirm flute profile, liner and medium papers, finished GSM and caliper, ECT/FCT or compression metrics, moisture, and the test standard before treating two China quotes as equivalent.

Identify the board build

The spec should show single, double, or triple wall; flute combination; and each paper layer from outer liner through medium to inner liner. “Five-layer” alone does not tell you the flute, paper weights, or strength. Ask for a cross-section notation when the sheet is unclear.

Read paper weights carefully

List GSM for every liner and medium, plus grade such as kraft, test liner, white-top, or recycled medium. Total GSM is not a substitute for layer details: moving weight from liners to medium can change puncture and compression behavior. Confirm permitted GSM tolerance and basis-weight test method.

Separate caliper from flute name

Flute letters indicate a profile family, but finished caliper varies with paper, machine settings, and compression. State the required caliper range after converting and conditioning. This matters for box fit, pallet cube, and die-cut settings.

Interpret strength claims

ECT measures edgewise strength of board; FCT and box compression tests address different conditions. A number is useful only with units, conditioning, sample orientation, and test method. Do not convert an ECT target into a guaranteed stacking result without an actual box design and load assumptions.

Check moisture and conditioning

Board moisture affects stiffness, print, glue, and warp. Request the stated moisture range and the laboratory conditioning standard. If cartons travel through humid ports or cold storage, ask whether the quoted test result was obtained under conditions relevant to the lane.

Look for conversion notes

Board may be supplied as sheets, rolls, printed blanks, or finished cartons. Confirm sheet size, grain/machine direction, score requirements, print face, and maximum warp. A raw-board spec that omits conversion tolerances is not a finished-cartons specification.

RFQ fields

Wall construction, flute profile, and layer-by-layer paper GSM/grade

Finished caliper, moisture, warp, and dimensional tolerances

ECT/FCT/BCT target with units, test method, and conditioning

Sheet/blank/carton format; print and score requirements

Quantity ladder; sample and test-report requirements; Incoterms

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How to Choose Corrugated Board, Corrugated Board ECT and FCT Explained, Single Wall vs Double Wall Corrugated Board, Corrugated Packaging Sourcing Guide, What Is White-Top Linerboard?