Recycled Containerboard Compression Loss under Constant Atmospheric Humidity
Recycled containerboard loses up to 45% compression strength under constant 85% RH; specify ISO 2233 derated SCT metrics to prevent static stack collapse.
Compression Loss
Structural Resistance
Board caliper reduction under sustained vertical load defines compression loss, occurring primarily during high stack storage in corrugated container manufacturing. Stacks of heavy transport cartons experience continuous downward force from upper layers, leading to gradual flute crushing and sidewall buckling over weeks in warehouse environments. Converting facilities calculate this downward stress threshold by measuring edge crush test values against prevailing ambient humidity levels, since moisture softens paper chemistry and accelerates structural fatigue.
Packaging engineers select specific flute profiles like C-flute or B-flute depending on stacking height requirements to maintain adequate box performance during distribution.
Creep Deformation
Creeping under load happens when packaging materials undergo permanent dimensional reduction after prolonged exposure to static weight. Paperboard behaves as a viscoelastic solid, meaning cellulose fibers slowly slide past one another when subjected to constant gravitational pressure. Humidity fluctuations exacerbate this movement because water molecules disrupt hydrogen bonds between fibers, reducing overall stiffness and accelerating box wall failure.
Converting plants mitigate this degradation by applying high performance starch adhesives and utilizing heavy linerboards during the corrugation process.
Stacking Margins
Safety factors applied to container design accommodate natural structural degradation over extended transport and storage durations. Box manufacturers calculate nominal edge crush strength and then apply reduction percentages to account for warehouse temperature variations, vibration during transit, and cyclic humidity changes. End users must verify that warehouse stacking patterns never exceed calculated load thresholds, because exceeding these limits results in catastrophic pallet collapse and product damage.