The compression strength of a corrugated box depends mainly on:
1. The edgewise compression strength (ECT) of the corrugated board.
2. The bending stiffness (BS) in both principal directions of the board.
Differences in the compression strength of A, B and C flute boxes is mainly
due to the differences in BS values of these boards. The ECTs of these
boards are very nearly equal; the minor differences being mainly
attributable to the take-up factor differences. These minor differences in
ECTs do not explain the fact that identically made boxes of C-Flute have
much stronger BCT values than B-flute. The reason is the BS of the different