Physical Phenomenon
Physical phenomena occurring inside shipping units cause atmospheric moisture to liquify on cold surfaces when the internal temperature drops below the dew point. Occurrence of container sweat condensation is a major risk for garments packed in corrugated boxes. Water droplets form on the ceiling and walls of the steel container before dripping onto the cargo.
Staining, mould growth, odours and the collapse of the packaging often follow this event. Managers must address the moisture levels of the packing material before the container is sealed.
Dew Point
Atmospheric limits determine when the transition from vapour to liquid will occur. In the context of container sweat condensation, the dew point is reached as the vessel moves from a tropical port into colder northern waters. Rapid cooling of the metal shell causes the air inside to become supersaturated.
Product Damage
Visual defects caused by water ingress reduce the commercial value of the textiles. If container sweat condensation is not controlled, the moisture can penetrate the polybags and soak the fabric. Wet spots often lead to the development of unpleasant odours or the migration of dyes.
Prevention Strategy
Mitigation involves the use of thermal liners and high-performance desiccants. Because container sweat condensation is driven by temperature gradients, insulating the cargo can reduce the rate of cooling. Strategic placement of moisture absorbers near the roof of the unit helps to capture vapour before it turns into liquid.
