How do I stop underwear packaging getting damp or mouldy in transit?

Short answer: Mould in transit usually comes from moisture already inside the goods and packaging, combined with temperature changes during the voyage. Cotton and paper absorb moisture from humid air; when a sealed container cools at night or moves to a cooler region, the moisture condenses on the container roof and walls and drips onto cartons, often called container rain. Damp cartons, wet pallets and goods packed straight after washing or pressing add to the problem. Prevent it by packing only dry, cooled garments, storing cartons off the floor in a dry area, using good quality cartons, sealing inner bags, using container desiccants sized for the load and checking the container before loading. Check moisture at packing if mould has happened before.

Where moisture comes from

• Garments packed warm or damp after finishing.
• Cartons and paper packaging stored in humid warehouses.
• Wooden pallets with high moisture content.
• Humid air sealed into the container at loading.
• Temperature swings during transit causing condensation.

Prevention at the factory

• Cool and dry garments fully after washing or pressing before bagging.
• Store finished cartons on pallets or racks, away from walls and floors.
• Keep paper packaging in a dry store.
• Seal garments in poly bags where suitable.

Prevention at loading

• Inspect the container for holes, damp floors and smells.
• Avoid loading in rain.
• Use container desiccant strips or bags sized for volume and voyage length.
• Use dry or treated pallets, or load cartons directly with dunnage.

Prevention for the packaging itself

• Choose cartons with suitable board grade for humid routes.
• Consider coated or moisture-resistant sleeves for long routes.
• Add sachet desiccants inside cartons for sensitive products.

Marketplace and retail packaging

Clear sealed poly bags protect against damp and dust. Amazon's prep guide, for example, requires textiles to be in sealed poly bags or shrink wrap to protect against dust, dirt and moisture.

If mould appears

• Separate affected cartons and record lot numbers.
• Check whether mould is on packaging only or on garments.
• Wash a sample per the care label, for example with an ISO 6330 procedure, to see whether marks and smell come out, before deciding on rework.

A worked example

For the shipment in the question, review packing records for time between pressing and packing, check where cartons were stored before loading and whether desiccants were used. On the next shipment, add a cooling time before bagging, store cartons on pallets and use container desiccants for the voyage length.

Limits

Humidity, voyage length and season vary. Plan for the worst conditions on your route.

Facts, recommendations and uncertainty

Established: transit mould comes from moisture in goods and packaging and condensation in containers. Recommendation: pack dry, store off the floor, use desiccants and inspect containers. Uncertain: conditions on each voyage.

Sources and further reading

• ISO 6330:2021 — Domestic washing and drying procedures for textile testing
• Amazon — Packaging and Shipping Inventory to Amazon (FBA prep guide)

Standards and regulations are referenced by their published scope. Test parameters, cycles and pass levels should be agreed with your laboratory for the specific product; legal requirements should be confirmed for each destination market.