Container Rain Is Physics, Not Bad Luck
A sealed 20ft or 40ft container is a sealed volume of moist air carrying thousands of grams of water, in the air itself and bound into wooden pallets, corrugated cartons, kraft paper and the cargo. As the vessel crosses climate zones, daytime solar gain heats the container skin 15–25°C above ambient and drives that moisture into the air as vapour. At night, or when the ship enters colder currents, the steel cools below the dew point of the enclosed air, and water condenses on the ceiling and walls and rains onto the cargo below. On a 25–45 day route, a single container can shed several litres of condensate per day during peak events, enough to rust steel, corrode electronics, collapse cartons and bloom mould on textiles.
The fix is not to fight the condensation after it forms but to remove the water vapour before relative humidity ever reaches the dew point. That requires a desiccant with enough capacity to keep absorbing for the entire voyage, and the absorption to accelerate, not plateau, exactly when humidity peaks. Silica gel cannot do this; it holds only ~25–40% of its weight and saturates early. High-purity calcium chloride does it, absorbing up to 300% of its weight and binding the captured water into a leak-proof gel. That is the engineering basis of the BENZPACK™ BE DRY™ container desiccant range.