Superdry desiccant will absorb up to 200% its own weight in moisture over a six week period, protecting cargo by maintaining a low humidity.
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Preventing moisture damage in cargo containers
Excess moisture within a cargo container can damage the contents through oxidation, discolouration or mould growth. It can also deteriorate packaging. As moisture damage can lead to a receiver rejecting the container at the port, poor humidity control can be very costly.
Although some moisture will enter the container on route, through air gaps in the doors and vents, the majority of the moisture inside a container will be present at packing and be contained in the cargo, packaging, pallets, dunnage, container floor and the air inside when the doors are shut.
By taking steps to minimise the volume of moisture introduced at packing and by actively removing moisture from the atmosphere, moisture damage during transit can be avoided.
Normally, moisture damage will be avoided if the atmosphere can be maintained at below 70%rH but this will depend on the cargo being shipping.
Steps to reduce the amount of moisture present inside a container include only using pallets and wooden dunnage that has a moisture content of 17% or less. If pallets are stored outside, they can soak up moisture that is later released into the container and its cargo. A hand held moisture meter is an economic and reliable way to tell whether pallets are suitable.
Plastic pallets, although more expensive than wooden pallets, present a moisture free alternative and help to minimise the moisture physically introduced to a container.
Ensure the container itself is as dry as possible. Was it just washed prior to packing? Have work boots carried in rain water or snow?
The temperature of the contents can play a significant role in moisture build-up. Packing a warm container with cold products can cause condensation as can packing a cold container with warm products. If possible equalise the container and contents temperature prior to packing.
Tightly wrapping a pallet with shrink wrap will not stop moisture problems. Any moisture already present inside the shrink wrap can condense on to the product or inside of the wrapping. This moisture could be present in the air, the pallet or the product itself. Leaving a gap at the top and bottom of the pallet can allow air to travel around the product and placing desiccant inside of the wrapping will also help avoid moisture damage.
Whether or not to seal a containers air vents depends largely on the cargo being shipped. The air inside a container will try to achieve equilibrium with the contents. Cargo will absorb moisture from humid air but likewise cargo will give up its moisture to a dry atmosphere. When shipping dry cargoes it is advisable to tape the vents shut to avoid moisture being sucked in by a dry internal atmosphere. For a moist cargo, leave the vents open.