There is one solution for every moisture related problem in containers is ABS CONTAINER DESICCANTS

Whoever has opened a shipping container only to find his valuable cargo rusted, moldy, and dripping with water can readily appreciate the dangers of moisture in container transports. Most cases of moisture damage are far less severe - peeling labels, spotted surfaces, or soggy packaging-, but are nonetheless unacceptable. Every year millions of shipments arrive damaged, causing losses of hundreds of millions of dollars from lower quality as well as additional costs for handling and administration. And in most cases, such damage is not even covered by the insurance and if so, insurance companies will make a huge loss on this problem.

The root cause of moisture damage in container transport is the simple fact that warm air can hold more moisture than cold air. Take the dewy grass in the morning after a cool summer night as an example. Moisture gets into the air in the container from the outside or by evaporation from the cargo. When the temperature in the container changes or there is a difference in temperature between different parts of the cargo, damaging moisture conditions arise.

Moisture damage happens even where there is no condensation. Many grades of steel will start to corrode at a relative humidity of about 70%. Mold growth could begin after even a short period of over 80%.

The only remedy is to keep the air inside the container dry. The first thing to do is to ensure that the cargo and all the packaging are as dry as possible. A wet container floor or some pallets stored in the rain may be enough to ruin a cargo.

No container is airtight whatever you do, - it will "breathe" as a result of temperature cycles. When the air inside the container cools, the pressure drops. Air - and moisture - move in from the outside to equalize the pressure. The opposite happens when the air inside the container heats up, but it is easy to show how a repeating cycle of breathing can cause a build-up of moisture inside the container, especially if there are absorbing packing materials. Using a container with good seals and vents taped shut will slow down, but not stop- the -container breathing".

Packaging and wrapping the goods in plastic foil will not necessarily help. Moisture migrates quite quickly through most types of plastic foil. Even if a moisture-proof foil is used, there could still be a problem since the sealed package then in effect becomes a "mini-container" subject to the same processes as the container.

Substances that remove moisture from the air are called "desiccants". The most widely used desiccants are probably "silica gel and clay-based products", a kind of porous glassy substance that adsorbs moisture well under the right conditions. When used in containers they are fatally flawed in that they work best at room temperature, and not at all at the much higher temperatures often found in containers. Other widely used desiccants based on dried clay work to a little higher temperature, but then similarly fail in an even more dramatic way by leaking, sweating, and damaging.

The worst case is when the desiccant is already fully charged and then meets high temperature, followed by low temperature, eg as a result of a day and night cycle when the container is on the quayside. Much of the moisture absorbed is then first re-evaporated and then rained out. Sometimes the container will look as someone threw a bucket of water inside the container, and wet moldy desiccant bags are a common sight.

Desiccants based on calcium chloride, such as DryBag, have a vigorous absorption over a large temperature range. Desiccants based on a mixture of clay and calcium chloride are very good absorbers but are easily "over-saturated" or collecting plastic bags/boxes with calcium chloride, but they easily lose the moisture again as they do not turn the moisture into a hard gel. If an "over-saturated" absorbent meets dry conditions, eg as a result of a sudden increase in temperature, it will re-evaporate the moisture already absorbed in a very destructive way. Only calcium chloride absorbers, such as DryBag, that separate the absorbed moisture to keep it from contact with the air and transform it to a hard gel are free of this problem.