Condensation happens when water vapor in the warm air encounters a surface, such as the steel sides of a shipping container, cool enough to bring the vapour back to a liquid state. To combat this phenomenon we modify containers to include vents, whirly birds and insulation which help to control the internal temperature, allowing the container to breathe, preventing condensation from occurring. If practical, simply keeping the doors open helps considerably.

In situations where condensation in unavoidable, such as in tropical climates, some care must be taken to avoid oxidisation and eventually rust. Many shipping containers are coated with oxide resistant zinc paint, inside and out, which allows them to stay in good condition for years while withstanding the wear and tear of sea travel. If you are planning on using a container for the storage of dry goods you should consider implementing the above precautions or protecting your goods with some kind of waterproofing.