Moisture protection for containerised cargo – reducing cargo losses

Moisture protection for containerised cargo – reducing cargo losses

High humidity inside a cargo container leads to condensation that can drip onto and damage the contents. This can result in cargo losses
or sometimes even the whole container being rejected at port.

There are many factors that can cause this high humidity including the type of cargo being shipped, the quality of the container, the type of pallets being used or the position of the container on the boat. Some of these factors are easy to control but some are not. The problem mainly occurs at night after the warmth of the day has heated the air inside the container causing it to absorb moisture from any available source. During the night, the air cools and the moisture condenses out of the air onto the cold surfaces of container roof, walls and the cargo itself.

So how do you ensure your cargo does not arrive at its destination covered in mould? One kilo of Superdry container desiccant will absorb up to two litres of moisture across an eight week period. By hanging between 8-12 kilos of Superdry desiccant inside a 40ft cargo container, the moisture in the air is absorbed by the desiccant and the humidity is kept below the level at which condensation forms. By acting as a buffer during periods of high humidity, the desiccant protects the cargo from moisture damage for the duration of its journey. Superdry comes in a variety of sizes and options depending on the application. A 1kg Superdry Dry Pole has a hook attached at one end so it’s simple to position on strapping loops and a cardboard outer casing that keeps it rigid and easy to handle.

Its active ingredient is calcium chloride, which is a food grade product, and is many times more effective than silica or clay based desiccants.
The desiccant’s outer casing is a Dupont Tyvek spun-bound, one-way material that allows water to travel in but not escape. Also, as the moisture is absorbed, the calcium chloride turns to a gel, locking the moisture inside. Both these features ensure that the collected water cannot be re-absorbed by the atmosphere and guarantees leak-free performance. Alongside actively removing moisture from the air with desiccant to maintain a low humidity, it is also important to try to mitigate the amount of moisture being introduced to the container at loading.

Wood can hold a lot of water and wooden pallets as well as the wooden container flooring can both add a substantial volume of water to the air across a container’s voyage. Plastic pallets present a moisture-free alternative but are slightly more expensive. If wooden pallets are used it’s important that they have a moisture content of 17% or less. A simple handheld moisture meter can be used to test pallets as well as container flooring prior to use. For further advice on how to prevent moisture damage to containerised cargo or for a free sample of Superdry container desiccant call JS Desiccants on 01903 858658, visit or email