When requesting a quotation for a burger, fry or bakery box, the discussion often comes down to one figure: the board's grammage. The purchasing goal, however, is a box that carries the product, closes reliably and presents the print well. This guide explains how to read grammage alongside other material information and compare alternatives under consistent conditions. It concerns folding paperboard cartons; corrugated packaging needs its own assessment.
1. Read grammage and thickness as separate properties
Grammage expresses mass per unit area in g/m²; thickness describes the board's cross-sectional dimension, usually in micrometres. One cannot substitute for the other. Holmen's technical glossary treats them separately.
Create separate columns for grammage and thickness in your quotation comparison. Add manufacturer, grade code and coating information. Do not assume two offers described only as “300 gsm board” specify the same material. Approving an equivalent before those details are complete leaves future repeat orders without a clear material reference.
2. Request stiffness with the test method and direction
Stiffness describes resistance to bending. The MetsäBoard Classic FBB specification lists separate values for different test methods and MD/CD directions. Before comparing two figures, check that method, unit and direction match.
Buyers do not need to establish a laboratory; they need comparable information. Place the current board's data sheet beside the proposed alternative. If methods differ, do not simply rank the numbers: ask the manufacturer to interpret them and include a finished-box trial in the decision. A data-sheet value alone does not describe how a filled box will carry its contents.
3. Mark grain direction on the sample and sheet layout
MD means machine direction; CD is perpendicular to it. Holmen relates directional stiffness to fibre orientation. Connect this information to the approved sample instead of leaving it only on the material sheet.
Ask for an MD arrow on the flat box blank. If a blank is rotated by 90 degrees to fit more boxes on a sheet, record that as a change and retest. Do not derive a universal rule for all boxes by bending one sample in your hand. Lid, side walls and base have different tasks, so the final orientation needs assessment within the specific box design.
4. Compare alternatives in a controlled sample trial
Code the current box as reference A and the proposed material as B. Keep product dimensions, fill quantity, closure and trial duration consistent. Where possible, change only the board in the first round. Changing dimensions, printing and locking features at the same time makes it harder to identify why performance changed.
Observe empty-box assembly and closure first, then handling with the real product. Record base sag, lid opening, corner deformation and print appearance. An initial trial using ten boxes per candidate, for example, can reveal problems; that number is neither an acceptance standard nor a production guarantee. Where results remain unclear, agree a wider trial with the manufacturer.
- Identical product, fill and holding conditions
- Separate identification of box and material
- Photographs and counts of observed problems
- Use expectations agreed before testing
5. Assess lower grammage through both calculation and use
For a hypothetical blank area of 0.08 m², 300 g/m² board has a theoretical mass of 24 grams. At 280 g/m², the same area weighs 22.4 grams: a difference of 1.6 grams per box, or 16 kilograms over 10,000 boxes. This calculation covers only the stated board area; it excludes sheet-layout waste and separately applied printing, coatings or adhesive.
The result proves neither that the lighter alternative is suitable nor that purchasing costs fall by the same proportion. Material price, printing and cutting layout, production waste and problems during use need separate assessment. Do not approve an alternative that fails the trial merely for its theoretical weight reduction. Equally, higher grammage should not be treated as the automatic solution to every box problem.
6. Turn approval into a repeat-order material specification
Record manufacturer and grade, grammage, thickness, print face, any coating and direction on the blank. Keep the box drawing and sample date in the same record. Everyone can then see which properties require reassessment when a material substitution is proposed.
Tell the manufacturer the food type, contact arrangement, temperature and holding time, and request the relevant suitability documentation separately. Grammage is not proof of suitability for food use. Reference the approved material and sample when reordering instead of asking only for “the same box”; review proposed equivalents before production starts.
- Grade code, grammage and thickness
- Print face, coating and MD arrow
- Approved drawing and sample reference
- Change approval for substitute materials