Container desiccants are bags, strips or poles of moisture-absorbing material hung inside the container to take water out of the air. Liners are materials that keep the cargo away from the steel walls, floor and roof, from simple kraft paper sheets to a full plastic liner bag for bulk loads.
They are worth using for most dry agri goods on long sea routes, and especially for products that pick up moisture easily, such as dehydrated onion and garlic, spice powders and psyllium husk.
How desiccants work
As a container heats and cools on the voyage, moisture in the air and the cargo can condense on the cold steel. Desiccants absorb some of that moisture and lower the humidity inside. Many container desiccants are based on calcium chloride and turn the absorbed water into a gel held in the bag.
They hang from the side wall lashing points or sit in the corrugations, in the gap between the cargo and the wall. The number needed depends on the product, its moisture, the route and the season. Ask the supplier or desiccant maker for their recommendation for your product and route, and treat it as a guide.
Types of liner
- Kraft paper or corrugated board on the floor and walls. It stops bags touching damp steel and absorbs a little condensation.
- Roof lining, sometimes called a container blanket, to catch drips from the roof.
- Full container liner bags, used for bulk loose cargo such as grains, oilseeds or some meals, which is blown or poured in and discharged by tipping.
- Inner liners in each bag, such as polyethylene liners in PP woven bags, which protect the product rather than the container.
When they are needed
- Long voyages that cross climate zones, such as India to northern Europe or North America.
- Shipments loaded in the humid monsoon months, or in rain.
- Products that absorb moisture, cake or grow mould easily.
- Goods loaded near the top of their moisture limit.
- Containers that will sit at a port or in transhipment for a long time.
What they cannot fix
Desiccants and liners reduce condensation. They do not dry out wet cargo. If the goods are loaded above their moisture specification, or straight from a dryer while still warm, no amount of desiccant will save them. The main defence is dry product and a dry container, as explained in how to prevent container rain.
Write any requirement into your specification: liner type, desiccant use and whether the cost is included in the price. Our guide on writing an agri product specification shows where packing details fit.
How we help
We agree liner and desiccant requirements with the supplier when the order is placed, and our inspector checks they are fitted before the seal goes on. We also check moisture on the loading sample. Ask for a free sourcing review if your product is moisture sensitive.