The Tech Box

The Tech Box – July 2021

New Research - How Does Stacking Pattern Impact BCT?

More research has been completed by the Fibre Box Association (FBA) Technical Committee that can help refine design targets for today’s box customers. This is the second recent research project completed by the committee that analyzes current data for assessing the Environmental Factors used by package designers industry wide.

FBA first published environmental factors in the mid-1990s in the Fibre Box Handbook. The data facilitating the factors was generated decades before and had not been updated until these projects, though the industry’s manufacturing materials and systems has undeniably evolved. The published environmental factors consider moisture in the form of relative humidity (RH); unitization or pallet configurations; load-stacking; and excessive handling – some of what we now call “the single parcel delivery system” or omni-channel delivery.

The environmental factors established multipliers, or safety factors. These safety factors help designers determine how strong a package needs to be, based on the actual load it must support in the transport and storage environments it is expected to protect against.


first research project

, completed in 2019, looked at the impact of RH under load on modern containerboard converted in today’s box plants.

This new research project

examined the impact of stacking pattern on top to bottom box compression (BCT).

The study was performed at Rochester Institute of Technology by the RIT Packaging Science Department. Under the mentorship of the FBA Technical committee, they investigated columnar aligned, interlocked, and aligned-interlocked hybrid stacking patterns compared to single box BCT.

The study used 19.5” x 12” x 13” C-Flute, single wall RSC samples with two different board grades (32 ECT and 44 ECT). All the stacking patterns were tested using the 2 – otherwise identical case designs. 10 individual Box Compression Tests were performed for each board grade and 5 pallet load compression tests were performed for each board grade and pallet pattern variation.

All boxes were setup and flaps were hotmelt glued. Later they were pre-conditioned and conditioned according to TAPPI T 402. Individual cases were removed from the conditioned atmosphere, pallet loads were built directly on the base plate of the compression tester, and testing, TAPPI T804, was performed asap in lab ambient conditions. Boxes in stacking pattern tests were filled to approximately 45 lb. gross weight (bagged road-salt with plywood spreaders.)

The originally published factors showed a compression loss of 0-8% for columnar aligned, and 40-60% loss for interlocked. Results from this study showed compression loss associated with aligned stacking exceeded the current values in the

Fibre Box Handbook

, and data was consistent with current values for interlocked stacking pattern BCT vs. single box BCT.

Based on the data gathered through the project, potential compression loss for columnar aligned is 12-20%. Interlocked units had 49-54% loss. The hybrid samples (not in the


, yet) had 45-49% loss.

FBA recently held a free webinar for members on the new research. Members of the FBA Technical Research Sub-Committee, Jerry Loza of Packaging Corporation of America and Steven Johnson of WestRock, did a wonderful job providing an overview of the project, sharing findings and explaining how the data can be used. I would encourage all FBA members to watch the archived webinar




Mary Alice

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Mary Alice Drain is the Director of Technical Services at Fibre Box Association (FBA). If you have technical questions about the corrugated industry, you can reach her direct at