Shipping containers are not climate controlled
Footwear made in the Far East and shipped to the UK typically spends several weeks at sea. A shipping container is a sealed steel box. It heats up by day and cools at night, and when it passes through tropical routes the air inside carries a lot of moisture.
When warm, moist air meets a cooler surface, condensation forms. In a container, that moisture can drip back onto the cargo, which is sometimes called container rain. Footwear and its packaging are full of materials mould grows on readily: leather, textile linings, adhesives, tissue paper and cardboard.
Longer journeys give mould more time
Under normal conditions, with the right precautions, a standard journey should not lead to mould. Delays change that. Congested ports, rerouted vessels and missed connections can add weeks to transit time, and every extra week in a warm, humid container gives spores more time to take hold. A delay of a few weeks can be enough for mould to spread across a whole shipment.
Preventative measures are sometimes missed
Factories have traditionally protected finished goods before containerisation, using silica gel sachets, mould-inhibiting packaging and preventative sprays. Under cost pressure, some of these measures are sometimes omitted, under-applied or replaced with lower-grade alternatives that do not last for a long modern journey. The goods then arrive without the protection they needed.
Why it is not always obvious when the doors open
Mould can be present but not yet widespread when a container is first opened. Once the stock is moved into a warm warehouse it can develop quickly. A musty smell on opening is often the first sign, and it is worth taking seriously even when the visible growth looks limited.
What this means for importers and retailers
Because contamination is uneven, the affected units are not always the ones that look worst. If a container shows clear signs of mould, the safest course is usually to treat the whole consignment rather than only the units with visible growth. Repacking untreated units alongside treated ones makes it more likely the problem returns.
What to do if a shipment arrives mouldy
- Isolate the affected stock from sound stock.
- Photograph the container, the cartons and some opened units.
- Record what you found and when, and inform your supplier, forwarder or insurer as appropriate.
- Avoid repacking the stock into clean cartons until it has been treated.
- Get specialist advice before deciding to write the stock off.
Signs to look for when a container is opened
- A musty or earthy smell as the doors open
- White, grey or green bloom on boxes, uppers or linings
- Fine spotting on printed box surfaces
- Damp, soft or stained outer cartons
- Water marks on the container walls or roof
Which materials are most at risk
Mould grows most readily on natural and absorbent materials. Leather and suede, textile linings, insoles, tissue paper and cardboard are usually affected first. Synthetics and rubber are less prone, but mould can still grow on dirt, adhesive or moisture on their surface, and the packaging around them is often affected even when the shoe is not.
How we can help
We remediate mould-affected footwear and apparel at our facility in Rossendale. Every unit is inspected, treated with products suited to its materials, dried, repacked and inspected again before it is released. If you are dealing with an affected shipment, or want a remediation partner in place before the next one, we would be glad to talk.
This article describes common causes in general terms. When we remediate a consignment, we do not give an opinion on the cause of mould in that consignment or on where in the supply chain it occurred.