Carton moisture starts before the container is closed
Many exporters think moisture damage starts during sea freight, but the risk often begins inside the packing area. Humid air, damp cartons, wooden pallets, wet floors, newly produced goods, and slow staging before loading can all add vapor before the goods even leave the factory. Silica gel helps, but it should be part of a packing workflow rather than a last-minute accessory.
- Store cartons and packaging material in a dry area before packing.
- Avoid packing goods immediately after washing, steaming, curing, or humid handling.
- Use desiccants before cartons are sealed, not after moisture has already built up.
Match sachet size to carton volume and product risk
A small sachet may work for a compact unit pack but fail inside a large export carton with air space and humidity exposure. Sensitive goods such as electronics, leather, footwear, paper labels, metal parts, and dry food cartons may need stronger protection than durable plastic goods. The right packet size depends on carton volume, barrier quality, storage duration, and destination humidity.
- Use 0.5g to 10g sachets for small boxes, accessories, pouches, and compact cartons.
- Use 25g to 100g or larger bags for master cartons, crates, and heavier packaging.
- Use container strips when the shipment risk is condensation across pallets or container walls.
Placement affects performance
Desiccants should be placed where vapor can reach them. A packet buried under dense product layers or blocked by plastic wrapping will work less efficiently. In export cartons, buyers should decide whether the desiccant protects the unit pack, master carton, pallet, or container environment.
- Place packets inside the sealed product pack when unit-level protection is needed.
- Place larger bags in master cartons where carton-level moisture is the problem.
- Keep container strips exposed to container air rather than sealed inside a product carton.
Document the packing standard
For repeat export orders, moisture prevention should be written into a packing checklist. This helps factory teams repeat the same dosage, packet placement, carton count, and loading method each shipment. It also gives procurement and quality teams a clearer basis for supplier discussions if damage or claims happen later.
- Record packet size, number of packets per carton, carton size, and shipment route.
- Request SDS and COA for the desiccant lot when required by the buyer.
- Use photos or packing records for high-value export programs.