Edge crush test (ECT)
The load per inch of edge that a short column of board carries standing on its edge, flutes vertical.
In practice
It is measured by TAPPI T 811 or T 839 and reported in lb/in. Because a box fails in its walls, ECT predicts stacking strength well, which is why the McKee formula uses it.
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Related terms
- Box compression test (BCT)
- The top-to-bottom load an empty box carries before it fails, measured between two platens in a compression tester.
- McKee formula
- An equation from McKee, Gander and Wachuta (1963) that estimates box compression strength from edge crush, caliper and perimeter.
- Mullen test
- The common name for the bursting-strength test of board, after the Mullen tester.
- Box maker's certificate
- A printed stamp, usually on a bottom flap, in which the box maker certifies that the box meets a carrier classification rule.
- Bursting strength
- The pressure a sheet of board withstands before a rubber diaphragm pushes through it.
- TAPPI
- The Technical Association of the Pulp and Paper Industry, which publishes paper and board test methods such as T 811 (ECT).
Definitions written by Packgent, last reviewed 2026-10-27. All terms.