Hygrometric Condensation
Moisture accumulation inside a corrugated cargo enclosure creates structural damage when ambient temperature drops below the dew point of trapped air. Container sweat ruins paper packaging through localized saturation that collapses the fluting medium and softens liners before shipment arrival. Condensation forms from moisture migrating out of wooden pallets and high-humidity paperboard stock under diurnal thermal cycling.
Dew point differentials drive water vapor from porous substrates directly onto the interior ceiling and sidewalls. Droplets fall onto stacked cartons and weaken box compression strength during ocean transit. Converted corrugated boxes lose stacking integrity rapidly when relative humidity inside the enclosure reaches saturation levels.
Vapor Barrier
Polyethylene film liners mitigate condensation damage by sealing dry paper loads away from the fluctuating microclimate inside steel enclosures. Desiccant bags absorb excess water vapor to keep relative humidity below the critical threshold for linerboard softening. Mill-applied hydrophobic coatings retard moisture absorption when ambient conditions force water vapor against outer shipping containers.
Kraft paper outer plies withstand moderate vapor exposure only when sizing agents prevent capillary absorption through the sheet. Barrier effectiveness depends entirely upon seal integrity at every seam of the protective envelope.
Dew Point
Ambient temperature drops below the internal vapor temperature and triggers liquid precipitation across uninsulated metal walls. Calculation models track external weather changes to predict condensation risk before loading operations commence. Temperature differentials between hull surfaces and cargo interiors dictate the rate of moisture transfer from wood pallets into surrounding paper packaging.
Water vapor pressure rises inside the enclosure as solar radiation heats the exterior steel panels during daytime transit hours. Subsequent nighttime cooling condenses the suspended moisture directly onto the coldest packaging surfaces.
